-This is Info file bashref.info, produced by Makeinfo version 1.68 from
-the input file /usr/homes/chet/src/bash/src/doc/bashref.texi.
+This is bashref.info, produced by makeinfo version 4.7 from
+/Users/chet/src/bash/src/doc/bashref.texi.
-INFO-DIR-SECTION Utilities
-START-INFO-DIR-ENTRY
-* Bash: (bash). The GNU Bourne-Again SHell.
-END-INFO-DIR-ENTRY
+ This text is a brief description of the features that are present in
+the Bash shell (version 3.0, 27 July 2004).
-This text is a brief description of the features that are present in
-the Bash shell.
+ This is Edition 3.0, last updated 27 July 2004, of `The GNU Bash
+Reference Manual', for `Bash', Version 3.0.
-This is Edition 2.4, last updated 14 March 2000,
-of `The GNU Bash Reference Manual',
-for `Bash', Version 2.04.
+ Copyright (C) 1988-2004 Free Software Foundation, Inc.
-Copyright (C) 1991-1999 Free Software Foundation, Inc.
+ Permission is granted to make and distribute verbatim copies of this
+manual provided the copyright notice and this permission notice are
+preserved on all copies.
-Permission is granted to make and distribute verbatim copies of
-this manual provided the copyright notice and this permission notice
-are preserved on all copies.
+ Permission is granted to copy, distribute and/or modify this
+ document under the terms of the GNU Free Documentation License,
+ Version 1.1 or any later version published by the Free Software
+ Foundation; with no Invariant Sections, with the Front-Cover texts
+ being "A GNU Manual," and with the Back-Cover Texts as in (a)
+ below. A copy of the license is included in the section entitled
+ "GNU Free Documentation License."
-Permission is granted to copy and distribute modified versions of this
-manual under the conditions for verbatim copying, provided that the entire
-resulting derived work is distributed under the terms of a permission
-notice identical to this one.
+ (a) The FSF's Back-Cover Text is: "You have freedom to copy and
+ modify this GNU Manual, like GNU software. Copies published by
+ the Free Software Foundation raise funds for GNU development."
-Permission is granted to copy and distribute translations of this manual
-into another language, under the above conditions for modified versions,
-except that this permission notice may be stated in a translation approved
-by the Free Software Foundation.
+INFO-DIR-SECTION Basics
+START-INFO-DIR-ENTRY
+* Bash: (bash). The GNU Bourne-Again SHell.
+END-INFO-DIR-ENTRY
\1f
File: bashref.info, Node: Top, Next: Introduction, Prev: (dir), Up: (dir)
Bash Features
*************
- This text is a brief description of the features that are present in
-the Bash shell.
-
- This is Edition 2.4, last updated 14 March 2000, of `The GNU Bash
-Reference Manual', for `Bash', Version 2.04.
+This text is a brief description of the features that are present in
+the Bash shell (version 3.0, 27 July 2004)..
- Copyright (C) 1991, 1993, 1996 Free Software Foundation, Inc.
+ This is Edition 3.0, last updated 27 July 2004, of `The GNU Bash
+Reference Manual', for `Bash', Version 3.0.
Bash contains features that appear in other popular shells, and some
features that only appear in Bash. Some of the shells that Bash has
between Bash and historical
versions of /bin/sh.
+* Copying This Manual:: Copying this manual.
+
* Builtin Index:: Index of Bash builtin commands.
* Reserved Word Index:: Index of Bash reserved words.
\1f
File: bashref.info, Node: Introduction, Next: Definitions, Prev: Top, Up: Top
-Introduction
-************
+1 Introduction
+**************
* Menu:
\1f
File: bashref.info, Node: What is Bash?, Next: What is a shell?, Up: Introduction
-What is Bash?
-=============
+1.1 What is Bash?
+=================
- Bash is the shell, or command language interpreter, for the GNU
+Bash is the shell, or command language interpreter, for the GNU
operating system. The name is an acronym for the `Bourne-Again SHell',
a pun on Stephen Bourne, the author of the direct ancestor of the
-current Unix shell `/bin/sh', which appeared in the Seventh Edition
-Bell Labs Research version of Unix.
+current Unix shell `sh', which appeared in the Seventh Edition Bell
+Labs Research version of Unix.
Bash is largely compatible with `sh' and incorporates useful
features from the Korn shell `ksh' and the C shell `csh'. It is
version of `csh', Bash is the default shell. Like other GNU software,
Bash is quite portable. It currently runs on nearly every version of
Unix and a few other operating systems - independently-supported ports
-exist for MS-DOS, OS/2, Windows 95/98, and Windows NT.
+exist for MS-DOS, OS/2, and Windows platforms.
\1f
File: bashref.info, Node: What is a shell?, Prev: What is Bash?, Up: Introduction
-What is a shell?
-================
+1.2 What is a shell?
+====================
- At its base, a shell is simply a macro processor that executes
-commands. A Unix shell is both a command interpreter, which provides
-the user interface to the rich set of GNU utilities, and a programming
-language, allowing these utilitites to be combined. Files containing
+At its base, a shell is simply a macro processor that executes
+commands. The term macro processor means functionality where text and
+symbols are expanded to create larger expressions.
+
+ A Unix shell is both a command interpreter and a programming
+language. As a command interpreter, the shell provides the user
+interface to the rich set of GNU utilities. The programming language
+features allow these utilitites to be combined. Files containing
commands can be created, and become commands themselves. These new
commands have the same status as system commands in directories such as
-`/bin', allowing users or groups to establish custom environments.
+`/bin', allowing users or groups to establish custom environments to
+automate their common tasks.
+
+ Shells may be used interactively or non-interactively. In
+interactive mode, they accept input typed from the keyboard. When
+executing non-interactively, shells execute commands read from a file.
A shell allows execution of GNU commands, both synchronously and
asynchronously. The shell waits for synchronous commands to complete
in parallel with the shell while it reads and executes additional
commands. The "redirection" constructs permit fine-grained control of
the input and output of those commands. Moreover, the shell allows
-control over the contents of commands' environments. Shells may be
-used interactively or non-interactively: they accept input typed from
-the keyboard or from a file.
+control over the contents of commands' environments.
Shells also provide a small set of built-in commands ("builtins")
implementing functionality impossible or inconvenient to obtain via
Shells offer features geared specifically for interactive use rather
than to augment the programming language. These interactive features
-include job control, command line editing, history and aliases. Each
-of these features is described in this manual.
+include job control, command line editing, command history and aliases.
+Each of these features is described in this manual.
\1f
File: bashref.info, Node: Definitions, Next: Basic Shell Features, Prev: Introduction, Up: Top
-Definitions
-***********
+2 Definitions
+*************
- These definitions are used throughout the remainder of this manual.
+These definitions are used throughout the remainder of this manual.
`POSIX'
A family of open system standards based on Unix. Bash is
one of the following: `||', `&&', `&', `;', `;;', `|', `(', or `)'.
`exit status'
- The value returned by a command to its caller.
+ The value returned by a command to its caller. The value is
+ restricted to eight bits, so the maximum value is 255.
`field'
A unit of text that is the result of one of the shell expansions.
\1f
File: bashref.info, Node: Basic Shell Features, Next: Shell Builtin Commands, Prev: Definitions, Up: Top
-Basic Shell Features
-********************
+3 Basic Shell Features
+**********************
- Bash is an acronym for `Bourne-Again SHell'. The Bourne shell is
-the traditional Unix shell originally written by Stephen Bourne. All
-of the Bourne shell builtin commands are available in Bash, and the
-rules for evaluation and quoting are taken from the POSIX 1003.2
-specification for the `standard' Unix shell.
+Bash is an acronym for `Bourne-Again SHell'. The Bourne shell is the
+traditional Unix shell originally written by Stephen Bourne. All of
+the Bourne shell builtin commands are available in Bash, The rules for
+evaluation and quoting are taken from the POSIX specification for the
+`standard' Unix shell.
This chapter briefly summarizes the shell's `building blocks':
commands, control structures, shell functions, shell parameters, shell
* Shell Syntax:: What your input means to the shell.
* Shell Commands:: The types of commands you can use.
* Shell Functions:: Grouping commands by name.
-* Shell Parameters:: Special shell variables.
-* Shell Expansions:: How Bash expands variables and the various
+* Shell Parameters:: How the shell stores values.
+* Shell Expansions:: How Bash expands parameters and the various
expansions available.
* Redirections:: A way to control where input and output go.
* Executing Commands:: What happens when you run a command.
\1f
File: bashref.info, Node: Shell Syntax, Next: Shell Commands, Up: Basic Shell Features
-Shell Syntax
-============
+3.1 Shell Syntax
+================
* Menu:
\1f
File: bashref.info, Node: Shell Operation, Next: Quoting, Up: Shell Syntax
-Shell Operation
----------------
+3.1.1 Shell Operation
+---------------------
- The following is a brief description of the shell's operation when it
+The following is a brief description of the shell's operation when it
reads and executes a command. Basically, the shell does the following:
- 1. Reads its input from a file (*note Shell Scripts::.), from a string
+ 1. Reads its input from a file (*note Shell Scripts::), from a string
supplied as an argument to the `-c' invocation option (*note
- Invoking Bash::.), or from the user's terminal.
+ Invoking Bash::), or from the user's terminal.
2. Breaks the input into words and operators, obeying the quoting
rules described in *Note Quoting::. These tokens are separated by
`metacharacters'. Alias expansion is performed by this step
- (*note Aliases::.).
+ (*note Aliases::).
3. Parses the tokens into simple and compound commands (*note Shell
- Commands::.).
+ Commands::).
- 4. Performs the various shell expansions (*note Shell Expansions::.),
+ 4. Performs the various shell expansions (*note Shell Expansions::),
breaking the expanded tokens into lists of filenames (*note
- Filename Expansion::.) and commands and arguments.
+ Filename Expansion::) and commands and arguments.
- 5. Performs any necessary redirections (*note Redirections::.) and
+ 5. Performs any necessary redirections (*note Redirections::) and
removes the redirection operators and their operands from the
argument list.
- 6. Executes the command (*note Executing Commands::.).
+ 6. Executes the command (*note Executing Commands::).
7. Optionally waits for the command to complete and collects its exit
- status (*note Exit Status::.).
+ status (*note Exit Status::).
\1f
File: bashref.info, Node: Quoting, Next: Comments, Prev: Shell Operation, Up: Shell Syntax
-Quoting
--------
+3.1.2 Quoting
+-------------
* Menu:
treatment for special characters, to prevent reserved words from being
recognized as such, and to prevent parameter expansion.
- Each of the shell metacharacters (*note Definitions::.) has special
+ Each of the shell metacharacters (*note Definitions::) has special
meaning to the shell and must be quoted if it is to represent itself.
When the command history expansion facilities are being used, the
HISTORY EXPANSION character, usually `!', must be quoted to prevent
-history expansion. *Note Bash History Facilities:: for more details
-concerning history expansion. There are three quoting mechanisms: the
-ESCAPE CHARACTER, single quotes, and double quotes.
+history expansion. *Note Bash History Facilities::, for more details
+concerning history expansion.
+
+ There are three quoting mechanisms: the ESCAPE CHARACTER, single
+quotes, and double quotes.
\1f
File: bashref.info, Node: Escape Character, Next: Single Quotes, Up: Quoting
-Escape Character
-................
+3.1.2.1 Escape Character
+........................
- A non-quoted backslash `\' is the Bash escape character. It
-preserves the literal value of the next character that follows, with
-the exception of `newline'. If a `\newline' pair appears, and the
+A non-quoted backslash `\' is the Bash escape character. It preserves
+the literal value of the next character that follows, with the
+exception of `newline'. If a `\newline' pair appears, and the
backslash itself is not quoted, the `\newline' is treated as a line
continuation (that is, it is removed from the input stream and
effectively ignored).
\1f
File: bashref.info, Node: Single Quotes, Next: Double Quotes, Prev: Escape Character, Up: Quoting
-Single Quotes
-.............
+3.1.2.2 Single Quotes
+.....................
- Enclosing characters in single quotes (`'') preserves the literal
-value of each character within the quotes. A single quote may not occur
+Enclosing characters in single quotes (`'') preserves the literal value
+of each character within the quotes. A single quote may not occur
between single quotes, even when preceded by a backslash.
\1f
File: bashref.info, Node: Double Quotes, Next: ANSI-C Quoting, Prev: Single Quotes, Up: Quoting
-Double Quotes
-.............
+3.1.2.3 Double Quotes
+.....................
- Enclosing characters in double quotes (`"') preserves the literal
-value of all characters within the quotes, with the exception of `$',
-``', and `\'. The characters `$' and ``' retain their special meaning
-within double quotes (*note Shell Expansions::.). The backslash
-retains its special meaning only when followed by one of the following
+Enclosing characters in double quotes (`"') preserves the literal value
+of all characters within the quotes, with the exception of `$', ``',
+and `\'. The characters `$' and ``' retain their special meaning
+within double quotes (*note Shell Expansions::). The backslash retains
+its special meaning only when followed by one of the following
characters: `$', ``', `"', `\', or `newline'. Within double quotes,
backslashes that are followed by one of these characters are removed.
Backslashes preceding characters without a special meaning are left
unmodified. A double quote may be quoted within double quotes by
-preceding it with a backslash.
+preceding it with a backslash. When command history is being used, the
+double quote may not be used to quote the history expansion character.
The special parameters `*' and `@' have special meaning when in
-double quotes (*note Shell Parameter Expansion::.).
+double quotes (*note Shell Parameter Expansion::).
\1f
File: bashref.info, Node: ANSI-C Quoting, Next: Locale Translation, Prev: Double Quotes, Up: Quoting
-ANSI-C Quoting
-..............
+3.1.2.4 ANSI-C Quoting
+......................
- Words of the form `$'STRING'' are treated specially. The word
-expands to STRING, with backslash-escaped characters replaced as
-specifed by the ANSI C standard. Backslash escape sequences, if
-present, are decoded as follows:
+Words of the form `$'STRING'' are treated specially. The word expands
+to STRING, with backslash-escaped characters replaced as specified by
+the ANSI C standard. Backslash escape sequences, if present, are
+decoded as follows:
`\a'
alert (bell)
single quote
`\NNN'
- the character whose `ASCII' code is the octal value NNN (one to
+ the eight-bit character whose value is the octal value NNN (one to
three digits)
-`\xNNN'
- the character whose `ASCII' code is the hexadecimal value NNN (one
- to three digits)
+`\xHH'
+ the eight-bit character whose value is the hexadecimal value HH
+ (one or two hex digits)
+
+`\cX'
+ a control-X character
The expanded result is single-quoted, as if the dollar sign had not
been present.
\1f
File: bashref.info, Node: Locale Translation, Prev: ANSI-C Quoting, Up: Quoting
-Locale-Specific Translation
-...........................
+3.1.2.5 Locale-Specific Translation
+...................................
- A double-quoted string preceded by a dollar sign (`$') will cause
-the string to be translated according to the current locale. If the
+A double-quoted string preceded by a dollar sign (`$') will cause the
+string to be translated according to the current locale. If the
current locale is `C' or `POSIX', the dollar sign is ignored. If the
string is translated and replaced, the replacement is double-quoted.
+ Some systems use the message catalog selected by the `LC_MESSAGES'
+shell variable. Others create the name of the message catalog from the
+value of the `TEXTDOMAIN' shell variable, possibly adding a suffix of
+`.mo'. If you use the `TEXTDOMAIN' variable, you may need to set the
+`TEXTDOMAINDIR' variable to the location of the message catalog files.
+Still others use both variables in this fashion:
+`TEXTDOMAINDIR'/`LC_MESSAGES'/LC_MESSAGES/`TEXTDOMAIN'.mo.
+
\1f
File: bashref.info, Node: Comments, Prev: Quoting, Up: Shell Syntax
-Comments
---------
+3.1.3 Comments
+--------------
- In a non-interactive shell, or an interactive shell in which the
+In a non-interactive shell, or an interactive shell in which the
`interactive_comments' option to the `shopt' builtin is enabled (*note
-Bash Builtins::.), a word beginning with `#' causes that word and all
+Bash Builtins::), a word beginning with `#' causes that word and all
remaining characters on that line to be ignored. An interactive shell
without the `interactive_comments' option enabled does not allow
comments. The `interactive_comments' option is on by default in
\1f
File: bashref.info, Node: Shell Commands, Next: Shell Functions, Prev: Shell Syntax, Up: Basic Shell Features
-Shell Commands
-==============
+3.2 Shell Commands
+==================
- A simple shell command such as `echo a b c' consists of the command
+A simple shell command such as `echo a b c' consists of the command
itself followed by arguments, separated by spaces.
More complex shell commands are composed of simple commands arranged
* Pipelines:: Connecting the input and output of several
commands.
* Lists:: How to execute commands sequentially.
-* Looping Constructs:: Shell commands for iterative action.
-* Conditional Constructs:: Shell commands for conditional execution.
-* Command Grouping:: Ways to group commands.
+* Compound Commands:: Shell commands for control flow.
\1f
File: bashref.info, Node: Simple Commands, Next: Pipelines, Up: Shell Commands
-Simple Commands
----------------
+3.2.1 Simple Commands
+---------------------
- A simple command is the kind of command encountered most often.
-It's just a sequence of words separated by `blank's, terminated by one
-of the shell's control operators (*note Definitions::.). The first
-word generally specifies a command to be executed, with the rest of the
+A simple command is the kind of command encountered most often. It's
+just a sequence of words separated by `blank's, terminated by one of
+the shell's control operators (*note Definitions::). The first word
+generally specifies a command to be executed, with the rest of the
words being that command's arguments.
- The return status (*note Exit Status::.) of a simple command is its
+ The return status (*note Exit Status::) of a simple command is its
exit status as provided by the POSIX 1003.1 `waitpid' function, or
128+N if the command was terminated by signal N.
\1f
File: bashref.info, Node: Pipelines, Next: Lists, Prev: Simple Commands, Up: Shell Commands
-Pipelines
----------
+3.2.2 Pipelines
+---------------
- A `pipeline' is a sequence of simple commands separated by `|'.
+A `pipeline' is a sequence of simple commands separated by `|'.
The format for a pipeline is
[`time' [`-p']] [`!'] COMMAND1 [`|' COMMAND2 ...]
-The output of each command in the pipeline is connected to the input of
-the next command. That is, each command reads the previous command's
-output.
+The output of each command in the pipeline is connected via a pipe to
+the input of the next command. That is, each command reads the
+previous command's output.
The reserved word `time' causes timing statistics to be printed for
the pipeline once it finishes. The statistics currently consist of
builtins, shell functions, and pipelines. An external `time' command
cannot time these easily.
- If the pipeline is not executed asynchronously (*note Lists::.), the
+ If the pipeline is not executed asynchronously (*note Lists::), the
shell waits for all commands in the pipeline to complete.
Each command in a pipeline is executed in its own subshell (*note
-Command Execution Environment::.). The exit status of a pipeline is
-the exit status of the last command in the pipeline. If the reserved
-word `!' precedes the pipeline, the exit status is the logical negation
-of the exit status of the last command.
+Command Execution Environment::). The exit status of a pipeline is the
+exit status of the last command in the pipeline, unless the `pipefail'
+option is enabled (*note The Set Builtin::). If `pipefail' is enabled,
+the pipeline's return status is the value of the last (rightmost)
+command to exit with a non-zero status, or zero if all commands exit
+successfully. If the reserved word `!' precedes the pipeline, the exit
+status is the logical negation of the exit status as described above.
+The shell waits for all commands in the pipeline to terminate before
+returning a value.
\1f
-File: bashref.info, Node: Lists, Next: Looping Constructs, Prev: Pipelines, Up: Shell Commands
+File: bashref.info, Node: Lists, Next: Compound Commands, Prev: Pipelines, Up: Shell Commands
-Lists of Commands
------------------
+3.2.3 Lists of Commands
+-----------------------
- A `list' is a sequence of one or more pipelines separated by one of
-the operators `;', `&', `&&', or `||', and optionally terminated by one
-of `;', `&', or a `newline'.
+A `list' is a sequence of one or more pipelines separated by one of the
+operators `;', `&', `&&', or `||', and optionally terminated by one of
+`;', `&', or a `newline'.
Of these list operators, `&&' and `||' have equal precedence,
followed by `;' and `&', which have equal precedence.
+ A sequence of one or more newlines may appear in a `list' to delimit
+commands, equivalent to a semicolon.
+
If a command is terminated by the control operator `&', the shell
executes the command asynchronously in a subshell. This is known as
executing the command in the BACKGROUND. The shell does not wait for
the command to finish, and the return status is 0 (true). When job
-control is not active (*note Job Control::.), the standard input for
+control is not active (*note Job Control::), the standard input for
asynchronous commands, in the absence of any explicit redirections, is
redirected from `/dev/null'.
command executed in the list.
\1f
-File: bashref.info, Node: Looping Constructs, Next: Conditional Constructs, Prev: Lists, Up: Shell Commands
+File: bashref.info, Node: Compound Commands, Prev: Lists, Up: Shell Commands
-Looping Constructs
-------------------
+3.2.4 Compound Commands
+-----------------------
+
+* Menu:
+
+* Looping Constructs:: Shell commands for iterative action.
+* Conditional Constructs:: Shell commands for conditional execution.
+* Command Grouping:: Ways to group commands.
+
+ Compound commands are the shell programming constructs. Each
+construct begins with a reserved word or control operator and is
+terminated by a corresponding reserved word or operator. Any
+redirections (*note Redirections::) associated with a compound command
+apply to all commands within that compound command unless explicitly
+overridden.
+
+ Bash provides looping constructs, conditional commands, and
+mechanisms to group commands and execute them as a unit.
- Bash supports the following looping constructs.
+\1f
+File: bashref.info, Node: Looping Constructs, Next: Conditional Constructs, Up: Compound Commands
+
+3.2.4.1 Looping Constructs
+..........................
+
+Bash supports the following looping constructs.
Note that wherever a `;' appears in the description of a command's
syntax, it may be replaced with one or more newlines.
resultant list, with NAME bound to the current member. If `in
WORDS' is not present, the `for' command executes the COMMANDS
once for each positional parameter that is set, as if `in "$@"'
- had been specified (*note Special Parameters::.). The return
+ had been specified (*note Special Parameters::). The return
status is the exit status of the last command that executes. If
there are no items in the expansion of WORDS, no commands are
executed, and the return status is zero.
for (( EXPR1 ; EXPR2 ; EXPR3 )) ; do COMMANDS ; done
First, the arithmetic expression EXPR1 is evaluated according to
- the rules described below (*note Shell Arithmetic::.). The
+ the rules described below (*note Shell Arithmetic::). The
arithmetic expression EXPR2 is then evaluated repeatedly until it
evaluates to zero. Each time EXPR2 evaluates to a non-zero value,
COMMANDS are executed and the arithmetic expression EXPR3 is
command in LIST that is executed, or false if any of the
expressions is invalid.
- The `break' and `continue' builtins (*note Bourne Shell Builtins::.)
+
+ The `break' and `continue' builtins (*note Bourne Shell Builtins::)
may be used to control loop execution.
\1f
-File: bashref.info, Node: Conditional Constructs, Next: Command Grouping, Prev: Looping Constructs, Up: Shell Commands
+File: bashref.info, Node: Conditional Constructs, Next: Command Grouping, Prev: Looping Constructs, Up: Compound Commands
-Conditional Constructs
-----------------------
+3.2.4.2 Conditional Constructs
+..............................
`if'
The syntax of the `if' command is:
command completes. Any other value read causes NAME to be set to
null. The line read is saved in the variable `REPLY'.
- The COMMANDS are executed after each selection until a `break' or
- `return' command is executed, at which point the `select' command
- completes.
+ The COMMANDS are executed after each selection until a `break'
+ command is executed, at which point the `select' command completes.
Here is an example that allows the user to pick a filename from the
current directory, and displays the name and index of the file
(( EXPRESSION ))
The arithmetic EXPRESSION is evaluated according to the rules
- described below (*note Shell Arithmetic::.). If the value of the
+ described below (*note Shell Arithmetic::). If the value of the
expression is non-zero, the return status is 0; otherwise the
return status is 1. This is exactly equivalent to
let "EXPRESSION"
-
*Note Bash Builtins::, for a full description of the `let' builtin.
`[[...]]'
performed on the words between the `[[' and `]]'; tilde expansion,
parameter and variable expansion, arithmetic expansion, command
substitution, process substitution, and quote removal are
- performed.
+ performed. Conditional operators such as `-f' must be unquoted to
+ be recognized as primaries.
When the `==' and `!=' operators are used, the string to the right
of the operator is considered a pattern and matched according to
respectively, and 1 otherwise. Any part of the pattern may be
quoted to force it to be matched as a string.
+ An additional binary operator, `=~', is available, with the same
+ precedence as `==' and `!='. When it is used, the string to the
+ right of the operator is considered an extended regular expression
+ and matched accordingly (as in regex3)). The return value is 0 if
+ the string matches the pattern, and 1 otherwise. If the regular
+ expression is syntactically incorrect, the conditional
+ expression's return value is 2. If the shell option `nocaseglob'
+ (see the description of `shopt' in *Note Bash Builtins::) is
+ enabled, the match is performed without regard to the case of
+ alphabetic characters. Substrings matched by parenthesized
+ subexpressions within the regular expression are saved in the
+ array variable `BASH_REMATCH'. The element of `BASH_REMATCH' with
+ index 0 is the portion of the string matching the entire regular
+ expression. The element of `BASH_REMATCH' with index N is the
+ portion of the string matching the Nth parenthesized subexpression.
+
Expressions may be combined using the following operators, listed
in decreasing order of precedence:
`EXPRESSION1 || EXPRESSION2'
True if either EXPRESSION1 or EXPRESSION2 is true.
+ The `&&' and `||' operators do not evaluate EXPRESSION2 if the
+ value of EXPRESSION1 is sufficient to determine the return value
+ of the entire conditional expression.
- The `&&' and `||' commands do not execute EXPRESSION2 if the value
- of EXPRESSION1 is sufficient to determine the return value of the
- entire conditional expression.
\1f
-File: bashref.info, Node: Command Grouping, Prev: Conditional Constructs, Up: Shell Commands
+File: bashref.info, Node: Command Grouping, Prev: Conditional Constructs, Up: Compound Commands
-Grouping Commands
------------------
+3.2.4.3 Grouping Commands
+.........................
- Bash provides two ways to group a list of commands to be executed as
-a unit. When commands are grouped, redirections may be applied to the
+Bash provides two ways to group a list of commands to be executed as a
+unit. When commands are grouped, redirections may be applied to the
entire command list. For example, the output of all the commands in
the list may be redirected to a single stream.
( LIST )
Placing a list of commands between parentheses causes a subshell
- to be created, and each of the commands in LIST to be executed in
- that subshell. Since the LIST is executed in a subshell, variable
- assignments do not remain in effect after the subshell completes.
+ environment to be created (*note Command Execution Environment::),
+ and each of the commands in LIST to be executed in that subshell.
+ Since the LIST is executed in a subshell, variable assignments do
+ not remain in effect after the subshell completes.
`{}'
{ LIST; }
\1f
File: bashref.info, Node: Shell Functions, Next: Shell Parameters, Prev: Shell Commands, Up: Basic Shell Features
-Shell Functions
-===============
+3.3 Shell Functions
+===================
- Shell functions are a way to group commands for later execution
-using a single name for the group. They are executed just like a
-"regular" command. When the name of a shell function is used as a
-simple command name, the list of commands associated with that function
-name is executed. Shell functions are executed in the current shell
-context; no new process is created to interpret them.
+Shell functions are a way to group commands for later execution using a
+single name for the group. They are executed just like a "regular"
+command. When the name of a shell function is used as a simple command
+name, the list of commands associated with that function name is
+executed. Shell functions are executed in the current shell context;
+no new process is created to interpret them.
- Functions are declared using this syntax:
- [ `function' ] NAME () { COMMAND-LIST; }
+ Functions are declared using this syntax:
+ [ `function' ] NAME () COMPOUND-COMMAND [ REDIRECTIONS ]
This defines a shell function named NAME. The reserved word
`function' is optional. If the `function' reserved word is supplied,
-the parentheses are optional. The BODY of the function is the
-COMMAND-LIST between { and }. This list is executed whenever NAME is
-specified as the name of a command. The exit status of a function is
-the exit status of the last command executed in the body.
-
- Note that for historical reasons, the curly braces that surround the
-body of the function must be separated from the body by `blank's or
-newlines. This is because the braces are reserved words and are only
-recognized as such when they are separated by whitespace. Also, the
-COMMAND-LIST must be terminated with a semicolon or a newline.
+the parentheses are optional. The BODY of the function is the compound
+command COMPOUND-COMMAND (*note Compound Commands::). That command is
+usually a LIST enclosed between { and }, but may be any compound
+command listed above. COMPOUND-COMMAND is executed whenever NAME is
+specified as the name of a command. Any redirections (*note
+Redirections::) associated with the shell function are performed when
+the function is executed.
+
+ The exit status of a function definition is zero unless a syntax
+error occurs or a readonly function with the same name already exists.
+When executed, the exit status of a function is the exit status of the
+last command executed in the body.
+
+ Note that for historical reasons, in the most common usage the curly
+braces that surround the body of the function must be separated from
+the body by `blank's or newlines. This is because the braces are
+reserved words and are only recognized as such when they are separated
+by whitespace. Also, when using the braces, the LIST must be
+terminated by a semicolon, a `&', or a newline.
When a function is executed, the arguments to the function become
the positional parameters during its execution (*note Positional
-Parameters::.). The special parameter `#' that expands to the number of
-positional parameters is updated to reflect the change. Positional
-parameter `0' is unchanged. The `FUNCNAME' variable is set to the name
-of the function while the function is executing.
+Parameters::). The special parameter `#' that expands to the number of
+positional parameters is updated to reflect the change. Special
+parameter `0' is unchanged. The first element of the `FUNCNAME'
+variable is set to the name of the function while the function is
+executing. All other aspects of the shell execution environment are
+identical between a function and its caller with the exception that the
+`DEBUG' trap below) is not inherited unless the function has been given
+the `trace' attribute using the `declare' builtin or the `-o functrace'
+option has been enabled with the `set' builtin, (in which case all
+functions inherit the `DEBUG' trap). *Note Bourne Shell Builtins::,
+for the description of the `trap' builtin.
If the builtin command `return' is executed in a function, the
function completes and execution resumes with the next command after
-the function call. When a function completes, the values of the
-positional parameters and the special parameter `#' are restored to the
-values they had prior to the function's execution. If a numeric
-argument is given to `return', that is the function's return status;
-otherwise the functions's return status is the exit status of the last
-command executed before the `return'.
+the function call. Any command associated with the `RETURN' trap is
+executed before execution resumes. When a function completes, the
+values of the positional parameters and the special parameter `#' are
+restored to the values they had prior to the function's execution. If
+a numeric argument is given to `return', that is the function's return
+status; otherwise the function's return status is the exit status of
+the last command executed before the `return'.
Variables local to the function may be declared with the `local'
builtin. These variables are visible only to the function and the
commands it invokes.
+ Function names and definitions may be listed with the `-f' option to
+the `declare' or `typeset' builtin commands (*note Bash Builtins::).
+The `-F' option to `declare' or `typeset' will list the function names
+only (and optionally the source file and line number, if the `extdebug'
+shell option is enabled). Functions may be exported so that subshells
+automatically have them defined with the `-f' option to the `export'
+builtin (*note Bourne Shell Builtins::). Note that shell functions and
+variables with the same name may result in multiple identically-named
+entries in the environment passed to the shell's children. Care should
+be taken in cases where this may cause a problem.
+
Functions may be recursive. No limit is placed on the number of
recursive calls.
\1f
File: bashref.info, Node: Shell Parameters, Next: Shell Expansions, Prev: Shell Functions, Up: Basic Shell Features
-Shell Parameters
-================
+3.4 Shell Parameters
+====================
* Menu:
* Positional Parameters:: The shell's command-line arguments.
-* Special Parameters:: Parameters with special meanings.
+* Special Parameters:: Parameters denoted by special characters.
A PARAMETER is an entity that stores values. It can be a `name', a
-number, or one of the special characters listed below. For the shell's
-purposes, a VARIABLE is a parameter denoted by a `name'.
+number, or one of the special characters listed below. A VARIABLE is a
+parameter denoted by a `name'. A variable has a VALUE and zero or more
+ATTRIBUTES. Attributes are assigned using the `declare' builtin command
+(see the description of the `declare' builtin in *Note Bash Builtins::).
A parameter is set if it has been assigned a value. The null string
is a valid value. Once a variable is set, it may be unset only by using
A variable may be assigned to by a statement of the form
NAME=[VALUE]
-
-If VALUE is not given, the variable is assigned the null string. All
+ If VALUE is not given, the variable is assigned the null string. All
VALUEs undergo tilde expansion, parameter and variable expansion,
command substitution, arithmetic expansion, and quote removal (detailed
-below). If the variable has its `integer' attribute set (see the
-description of the `declare' builtin in *Note Bash Builtins::), then
-VALUE is subject to arithmetic expansion even if the `$((...))'
-expansion is not used (*note Arithmetic Expansion::.). Word splitting
-is not performed, with the exception of `"$@"' as explained below.
-Filename expansion is not performed.
+below). If the variable has its `integer' attribute set, then VALUE is
+evaluated as an arithmetic expression even if the `$((...))' expansion
+is not used (*note Arithmetic Expansion::). Word splitting is not
+performed, with the exception of `"$@"' as explained below. Filename
+expansion is not performed. Assignment statements may also appear as
+arguments to the `alias', `declare', `typeset', `export', `readonly',
+and `local' builtin commands.
\1f
File: bashref.info, Node: Positional Parameters, Next: Special Parameters, Up: Shell Parameters
-Positional Parameters
----------------------
+3.4.1 Positional Parameters
+---------------------------
- A POSITIONAL PARAMETER is a parameter denoted by one or more digits,
+A POSITIONAL PARAMETER is a parameter denoted by one or more digits,
other than the single digit `0'. Positional parameters are assigned
from the shell's arguments when it is invoked, and may be reassigned
using the `set' builtin command. Positional parameter `N' may be
referenced as `${N}', or as `$N' when `N' consists of a single digit.
Positional parameters may not be assigned to with assignment statements.
The `set' and `shift' builtins are used to set and unset them (*note
-Shell Builtin Commands::.). The positional parameters are temporarily
-replaced when a shell function is executed (*note Shell Functions::.).
+Shell Builtin Commands::). The positional parameters are temporarily
+replaced when a shell function is executed (*note Shell Functions::).
When a positional parameter consisting of more than a single digit
is expanded, it must be enclosed in braces.
\1f
File: bashref.info, Node: Special Parameters, Prev: Positional Parameters, Up: Shell Parameters
-Special Parameters
-------------------
+3.4.2 Special Parameters
+------------------------
- The shell treats several parameters specially. These parameters may
+The shell treats several parameters specially. These parameters may
only be referenced; assignment to them is not allowed.
`*'
`0'
Expands to the name of the shell or shell script. This is set at
shell initialization. If Bash is invoked with a file of commands
- (*note Shell Scripts::.), `$0' is set to the name of that file.
- If Bash is started with the `-c' option (*note Invoking Bash::.),
- then `$0' is set to the first argument after the string to be
- executed, if one is present. Otherwise, it is set to the filename
- used to invoke Bash, as given by argument zero.
+ (*note Shell Scripts::), `$0' is set to the name of that file. If
+ Bash is started with the `-c' option (*note Invoking Bash::), then
+ `$0' is set to the first argument after the string to be executed,
+ if one is present. Otherwise, it is set to the filename used to
+ invoke Bash, as given by argument zero.
`_'
(An underscore.) At shell startup, set to the absolute filename
\1f
File: bashref.info, Node: Shell Expansions, Next: Redirections, Prev: Shell Parameters, Up: Basic Shell Features
-Shell Expansions
-================
+3.5 Shell Expansions
+====================
- Expansion is performed on the command line after it has been split
-into `token's. There are seven kinds of expansion performed:
+Expansion is performed on the command line after it has been split into
+`token's. There are seven kinds of expansion performed:
* brace expansion
* tilde expansion
Only brace expansion, word splitting, and filename expansion can
change the number of words of the expansion; other expansions expand a
single word to a single word. The only exceptions to this are the
-expansions of `"$@"' (*note Special Parameters::.) and `"${NAME[@]}"'
-(*note Arrays::.).
+expansions of `"$@"' (*note Special Parameters::) and `"${NAME[@]}"'
+(*note Arrays::).
- After all expansions, `quote removal' (*note Quote Removal::.) is
+ After all expansions, `quote removal' (*note Quote Removal::) is
performed.
\1f
File: bashref.info, Node: Brace Expansion, Next: Tilde Expansion, Up: Shell Expansions
-Brace Expansion
----------------
+3.5.1 Brace Expansion
+---------------------
- Brace expansion is a mechanism by which arbitrary strings may be
+Brace expansion is a mechanism by which arbitrary strings may be
generated. This mechanism is similar to FILENAME EXPANSION (*note
-Filename Expansion::.), but the file names generated need not exist.
+Filename Expansion::), but the file names generated need not exist.
Patterns to be brace expanded take the form of an optional PREAMBLE,
-followed by a series of comma-separated strings between a pair of
-braces, followed by an optional POSTSCRIPT. The preamble is prefixed
-to each string contained within the braces, and the postscript is then
-appended to each resulting string, expanding left to right.
+followed by either a series of comma-separated strings or a sequnce
+expression between a pair of braces, followed by an optional POSTSCRIPT.
+The preamble is prefixed to each string contained within the braces, and
+the postscript is then appended to each resulting string, expanding left
+to right.
Brace expansions may be nested. The results of each expanded string
are not sorted; left to right order is preserved. For example,
bash$ echo a{d,c,b}e
ade ace abe
+ A sequence expression takes the form `{X..Y}', where X and Y are
+either integers or single characters. When integers are supplied, the
+expression expands to each number between X and Y, inclusive. When
+characters are supplied, the expression expands to each character
+lexicographically between X and Y, inclusive. Note that both X and Y
+must be of the same type.
+
Brace expansion is performed before any other expansions, and any
characters special to other expansions are preserved in the result. It
is strictly textual. Bash does not apply any syntactic interpretation
considered eligible for brace expansion.
A correctly-formed brace expansion must contain unquoted opening and
-closing braces, and at least one unquoted comma. Any incorrectly
-formed brace expansion is left unchanged.
+closing braces, and at least one unquoted comma or a valid sequence
+expression. Any incorrectly formed brace expansion is left unchanged.
+
+ A { or `,' may be quoted with a backslash to prevent its being
+considered part of a brace expression. To avoid conflicts with
+parameter expansion, the string `${' is not considered eligible for
+brace expansion.
This construct is typically used as shorthand when the common prefix
of the strings to be generated is longer than in the above example:
\1f
File: bashref.info, Node: Tilde Expansion, Next: Shell Parameter Expansion, Prev: Brace Expansion, Up: Shell Expansions
-Tilde Expansion
----------------
+3.5.2 Tilde Expansion
+---------------------
- If a word begins with an unquoted tilde character (`~'), all of the
+If a word begins with an unquoted tilde character (`~'), all of the
characters up to the first unquoted slash (or all characters, if there
is no unquoted slash) are considered a TILDE-PREFIX. If none of the
characters in the tilde-prefix are quoted, the characters in the
replaced with the corresponding element from the directory stack, as it
would be displayed by the `dirs' builtin invoked with the characters
following tilde in the tilde-prefix as an argument (*note The Directory
-Stack::.). If the tilde-prefix, sans the tilde, consists of a number
+Stack::). If the tilde-prefix, sans the tilde, consists of a number
without a leading `+' or `-', `+' is assumed.
If the login name is invalid, or the tilde expansion fails, the word
`~-N'
The string that would be displayed by `dirs -N'
+
\1f
File: bashref.info, Node: Shell Parameter Expansion, Next: Command Substitution, Prev: Tilde Expansion, Up: Shell Expansions
-Shell Parameter Expansion
--------------------------
+3.5.3 Shell Parameter Expansion
+-------------------------------
- The `$' character introduces parameter expansion, command
-substitution, or arithmetic expansion. The parameter name or symbol to
-be expanded may be enclosed in braces, which are optional but serve to
-protect the variable to be expanded from characters immediately
-following it which could be interpreted as part of the name.
+The `$' character introduces parameter expansion, command substitution,
+or arithmetic expansion. The parameter name or symbol to be expanded
+may be enclosed in braces, which are optional but serve to protect the
+variable to be expanded from characters immediately following it which
+could be interpreted as part of the name.
When braces are used, the matching ending brace is the first `}' not
escaped by a backslash or within a quoted string, and not within an
variable formed from the rest of PARAMETER as the name of the variable;
this variable is then expanded and that value is used in the rest of
the substitution, rather than the value of PARAMETER itself. This is
-known as `indirect expansion'. The exception to this is the expansion
-of ${!PREFIX*} described below.
+known as `indirect expansion'. The exceptions to this are the
+expansions of ${!PREFIX*} and ${!NAME[@]} described below. The
+exclamation point must immediately follow the left brace in order to
+introduce indirection.
In each of the cases below, WORD is subject to tilde expansion,
parameter expansion, command substitution, and arithmetic expansion.
`${PARAMETER:=WORD}'
If PARAMETER is unset or null, the expansion of WORD is assigned
to PARAMETER. The value of PARAMETER is then substituted.
- Positional parameters and special parameters may not be assigned
- to in this way.
+ Positional parameters and special parameters may not be assigned to
+ in this way.
`${PARAMETER:?WORD}'
If PARAMETER is null or unset, the expansion of WORD (or a message
character specified by OFFSET. If LENGTH is omitted, expands to
the substring of PARAMETER starting at the character specified by
OFFSET. LENGTH and OFFSET are arithmetic expressions (*note Shell
- Arithmetic::.). This is referred to as Substring Expansion.
+ Arithmetic::). This is referred to as Substring Expansion.
LENGTH must evaluate to a number greater than or equal to zero.
If OFFSET evaluates to a number less than zero, the value is used
starts at 1.
`${!PREFIX*}'
+`${!PREFIX@}'
Expands to the names of variables whose names begin with PREFIX,
separated by the first character of the `IFS' special variable.
+`${!NAME[@]}'
+`${!NAME[*]}'
+ If NAME is an array variable, expands to the list of array indices
+ (keys) assigned in NAME. If NAME is not an array, expands to 0 if
+ NAME is set and null otherwise. When `@' is used and the
+ expansion appears within double quotes, each key expands to a
+ separate word.
+
`${#PARAMETER}'
The length in characters of the expanded value of PARAMETER is
substituted. If PARAMETER is `*' or `@', the value substituted is
`${PARAMETER#WORD}'
`${PARAMETER##WORD}'
The WORD is expanded to produce a pattern just as in filename
- expansion (*note Filename Expansion::.). If the pattern matches
+ expansion (*note Filename Expansion::). If the pattern matches
the beginning of the expanded value of PARAMETER, then the result
of the expansion is the expanded value of PARAMETER with the
shortest matching pattern (the `#' case) or the longest matching
member of the array in turn, and the expansion is the resultant
list.
+
\1f
File: bashref.info, Node: Command Substitution, Next: Arithmetic Expansion, Prev: Shell Parameter Expansion, Up: Shell Expansions
-Command Substitution
---------------------
+3.5.4 Command Substitution
+--------------------------
- Command substitution allows the output of a command to replace the
+Command substitution allows the output of a command to replace the
command itself. Command substitution occurs when a command is enclosed
as follows:
$(COMMAND)
-
-or
+ or
`COMMAND`
Bash performs the expansion by executing COMMAND and replacing the
\1f
File: bashref.info, Node: Arithmetic Expansion, Next: Process Substitution, Prev: Command Substitution, Up: Shell Expansions
-Arithmetic Expansion
---------------------
+3.5.5 Arithmetic Expansion
+--------------------------
- Arithmetic expansion allows the evaluation of an arithmetic
-expression and the substitution of the result. The format for
-arithmetic expansion is:
+Arithmetic expansion allows the evaluation of an arithmetic expression
+and the substitution of the result. The format for arithmetic
+expansion is:
$(( EXPRESSION ))
The expression is treated as if it were within double quotes, but a
double quote inside the parentheses is not treated specially. All
tokens in the expression undergo parameter expansion, command
-substitution, and quote removal. Arithmetic substitutions may be
-nested.
+substitution, and quote removal. Arithmetic expansions may be nested.
The evaluation is performed according to the rules listed below
-(*note Shell Arithmetic::.). If the expression is invalid, Bash prints
+(*note Shell Arithmetic::). If the expression is invalid, Bash prints
a message indicating failure to the standard error and no substitution
occurs.
\1f
File: bashref.info, Node: Process Substitution, Next: Word Splitting, Prev: Arithmetic Expansion, Up: Shell Expansions
-Process Substitution
---------------------
+3.5.6 Process Substitution
+--------------------------
- Process substitution is supported on systems that support named
-pipes (FIFOs) or the `/dev/fd' method of naming open files. It takes
-the form of
+Process substitution is supported on systems that support named pipes
+(FIFOs) or the `/dev/fd' method of naming open files. It takes the
+form of
<(LIST)
-
-or
+ or
>(LIST)
-
-The process LIST is run with its input or output connected to a FIFO or
-some file in `/dev/fd'. The name of this file is passed as an argument
-to the current command as the result of the expansion. If the
+ The process LIST is run with its input or output connected to a FIFO
+or some file in `/dev/fd'. The name of this file is passed as an
+argument to the current command as the result of the expansion. If the
`>(LIST)' form is used, writing to the file will provide input for
LIST. If the `<(LIST)' form is used, the file passed as an argument
should be read to obtain the output of LIST. Note that no space may
\1f
File: bashref.info, Node: Word Splitting, Next: Filename Expansion, Prev: Process Substitution, Up: Shell Expansions
-Word Splitting
---------------
+3.5.7 Word Splitting
+--------------------
- The shell scans the results of parameter expansion, command
+The shell scans the results of parameter expansion, command
substitution, and arithmetic expansion that did not occur within double
quotes for word splitting.
\1f
File: bashref.info, Node: Filename Expansion, Next: Quote Removal, Prev: Word Splitting, Up: Shell Expansions
-Filename Expansion
-------------------
+3.5.8 Filename Expansion
+------------------------
* Menu:
* Pattern Matching:: How the shell matches patterns.
After word splitting, unless the `-f' option has been set (*note The
-Set Builtin::.), Bash scans each word for the characters `*', `?', and
+Set Builtin::), Bash scans each word for the characters `*', `?', and
`['. If one of these characters appears, then the word is regarded as
a PATTERN, and replaced with an alphabetically sorted list of file
names matching the pattern. If no matching file names are found, and
the shell option `nullglob' is disabled, the word is left unchanged.
If the `nullglob' option is set, and no matches are found, the word is
-removed. If the shell option `nocaseglob' is enabled, the match is
-performed without regard to the case of alphabetic characters.
+removed. If the `failglob' shell option is set, and no matches are
+found, an error message is printed and the command is not executed. If
+the shell option `nocaseglob' is enabled, the match is performed
+without regard to the case of alphabetic characters.
- When a pattern is used for filename generation, the character `.'
-at the start of a filename or immediately following a slash must be
+ When a pattern is used for filename generation, the character `.' at
+the start of a filename or immediately following a slash must be
matched explicitly, unless the shell option `dotglob' is set. When
matching a file name, the slash character must always be matched
explicitly. In other cases, the `.' character is not treated specially.
See the description of `shopt' in *Note Bash Builtins::, for a
-description of the `nocaseglob', `nullglob', and `dotglob' options.
+description of the `nocaseglob', `nullglob', `failglob', and `dotglob'
+options.
The `GLOBIGNORE' shell variable may be used to restrict the set of
filenames matching a pattern. If `GLOBIGNORE' is set, each matching
filename that also matches one of the patterns in `GLOBIGNORE' is
-removed from the list of matches. The filenames `.' and `..' are
-always ignored, even when `GLOBIGNORE' is set. However, setting
-`GLOBIGNORE' has the effect of enabling the `dotglob' shell option, so
-all other filenames beginning with a `.' will match. To get the old
-behavior of ignoring filenames beginning with a `.', make `.*' one of
-the patterns in `GLOBIGNORE'. The `dotglob' option is disabled when
-`GLOBIGNORE' is unset.
+removed from the list of matches. The filenames `.' and `..' are
+always ignored when `GLOBIGNORE' is set and not null. However, setting
+`GLOBIGNORE' to a non-null value has the effect of enabling the
+`dotglob' shell option, so all other filenames beginning with a `.'
+will match. To get the old behavior of ignoring filenames beginning
+with a `.', make `.*' one of the patterns in `GLOBIGNORE'. The
+`dotglob' option is disabled when `GLOBIGNORE' is unset.
\1f
File: bashref.info, Node: Pattern Matching, Up: Filename Expansion
-Pattern Matching
-................
+3.5.8.1 Pattern Matching
+........................
- Any character that appears in a pattern, other than the special
-pattern characters described below, matches itself. The NUL character
-may not occur in a pattern. The special pattern characters must be
-quoted if they are to be matched literally.
+Any character that appears in a pattern, other than the special pattern
+characters described below, matches itself. The NUL character may not
+occur in a pattern. A backslash escapes the following character; the
+escaping backslash is discarded when matching. The special pattern
+characters must be quoted if they are to be matched literally.
The special pattern characters have the following meanings:
`*'
`[...]'
Matches any one of the enclosed characters. A pair of characters
- separated by a minus sign denotes a RANGE; any character lexically
- between those two characters, inclusive, is matched. If the first
- character following the `[' is a `!' or a `^' then any character
- not enclosed is matched. A `-' may be matched by including it as
- the first or last character in the set. A `]' may be matched by
- including it as the first character in the set.
+ separated by a hyphen denotes a RANGE EXPRESSION; any character
+ that sorts between those two characters, inclusive, using the
+ current locale's collating sequence and character set, is matched.
+ If the first character following the `[' is a `!' or a `^' then
+ any character not enclosed is matched. A `-' may be matched by
+ including it as the first or last character in the set. A `]' may
+ be matched by including it as the first character in the set. The
+ sorting order of characters in range expressions is determined by
+ the current locale and the value of the `LC_COLLATE' shell
+ variable, if set.
+
+ For example, in the default C locale, `[a-dx-z]' is equivalent to
+ `[abcdxyz]'. Many locales sort characters in dictionary order,
+ and in these locales `[a-dx-z]' is typically not equivalent to
+ `[abcdxyz]'; it might be equivalent to `[aBbCcDdxXyYz]', for
+ example. To obtain the traditional interpretation of ranges in
+ bracket expressions, you can force the use of the C locale by
+ setting the `LC_COLLATE' or `LC_ALL' environment variable to the
+ value `C'.
Within `[' and `]', CHARACTER CLASSES can be specified using the
syntax `[:'CLASS`:]', where CLASS is one of the following classes
defined in the POSIX 1003.2 standard:
alnum alpha ascii blank cntrl digit graph lower
- print punct space upper xdigit
-
+ print punct space upper word xdigit
A character class matches any character belonging to that class.
+ The `word' character class matches letters, digits, and the
+ character `_'.
Within `[' and `]', an EQUIVALENCE CLASS can be specified using
the syntax `[='C`=]', which matches all characters with the same
collation weight (as defined by the current locale) as the
character C.
- Within `[' and `]', the syntax `[.'SYMBOL`.]' matches the
+ Within `[' and `]', the syntax `[.'SYMBOL`.]' matches the
collating symbol SYMBOL.
If the `extglob' shell option is enabled using the `shopt' builtin,
\1f
File: bashref.info, Node: Quote Removal, Prev: Filename Expansion, Up: Shell Expansions
-Quote Removal
--------------
+3.5.9 Quote Removal
+-------------------
- After the preceding expansions, all unquoted occurrences of the
+After the preceding expansions, all unquoted occurrences of the
characters `\', `'', and `"' that did not result from one of the above
expansions are removed.
\1f
File: bashref.info, Node: Redirections, Next: Executing Commands, Prev: Shell Expansions, Up: Basic Shell Features
-Redirections
-============
+3.6 Redirections
+================
- Before a command is executed, its input and output may be REDIRECTED
+Before a command is executed, its input and output may be REDIRECTED
using a special notation interpreted by the shell. Redirection may
also be used to open and close files for the current shell execution
environment. The following redirection operators may precede or appear
Note that the order of redirections is significant. For example,
the command
ls > DIRLIST 2>&1
-
-directs both standard output (file descriptor 1) and standard error
+ directs both standard output (file descriptor 1) and standard error
(file descriptor 2) to the file DIRLIST, while the command
ls 2>&1 > DIRLIST
-
-directs only the standard output to file DIRLIST, because the standard
-error was duplicated as standard output before the standard output was
-redirected to DIRLIST.
+ directs only the standard output to file DIRLIST, because the
+standard error was duplicated as standard output before the standard
+output was redirected to DIRLIST.
Bash handles several filenames specially when they are used in
redirections, as described in the following table:
`/dev/tcp/HOST/PORT'
If HOST is a valid hostname or Internet address, and PORT is an
- integer port number, Bash attempts to open a TCP connection to the
- corresponding socket.
+ integer port number or service name, Bash attempts to open a TCP
+ connection to the corresponding socket.
`/dev/udp/HOST/PORT'
If HOST is a valid hostname or Internet address, and PORT is an
- integer port number, Bash attempts to open a UDP connection to the
- corresponding socket.
+ integer port number or service name, Bash attempts to open a UDP
+ connection to the corresponding socket.
+
A failure to open or create a file causes the redirection to fail.
-Redirecting Input
------------------
+3.6.1 Redirecting Input
+-----------------------
- Redirection of input causes the file whose name results from the
+Redirection of input causes the file whose name results from the
expansion of WORD to be opened for reading on file descriptor `n', or
the standard input (file descriptor 0) if `n' is not specified.
The general format for redirecting input is:
- [n]<WORD
+ [N]<WORD
-Redirecting Output
-------------------
+3.6.2 Redirecting Output
+------------------------
- Redirection of output causes the file whose name results from the
-expansion of WORD to be opened for writing on file descriptor `n', or
-the standard output (file descriptor 1) if `n' is not specified. If
-the file does not exist it is created; if it does exist it is truncated
-to zero size.
+Redirection of output causes the file whose name results from the
+expansion of WORD to be opened for writing on file descriptor N, or the
+standard output (file descriptor 1) if N is not specified. If the file
+does not exist it is created; if it does exist it is truncated to zero
+size.
The general format for redirecting output is:
- [n]>[|]WORD
+ [N]>[|]WORD
If the redirection operator is `>', and the `noclobber' option to
the `set' builtin has been enabled, the redirection will fail if the
operator is `>' and the `noclobber' option is not enabled, the
redirection is attempted even if the file named by WORD exists.
-Appending Redirected Output
----------------------------
+3.6.3 Appending Redirected Output
+---------------------------------
- Redirection of output in this fashion causes the file whose name
+Redirection of output in this fashion causes the file whose name
results from the expansion of WORD to be opened for appending on file
-descriptor `n', or the standard output (file descriptor 1) if `n' is
-not specified. If the file does not exist it is created.
+descriptor N, or the standard output (file descriptor 1) if N is not
+specified. If the file does not exist it is created.
The general format for appending output is:
- [n]>>WORD
+ [N]>>WORD
-Redirecting Standard Output and Standard Error
-----------------------------------------------
+3.6.4 Redirecting Standard Output and Standard Error
+----------------------------------------------------
- Bash allows both the standard output (file descriptor 1) and the
+Bash allows both the standard output (file descriptor 1) and the
standard error output (file descriptor 2) to be redirected to the file
whose name is the expansion of WORD with this construct.
There are two formats for redirecting standard output and standard
error:
&>WORD
-
-and
+ and
>&WORD
-
-Of the two forms, the first is preferred. This is semantically
+ Of the two forms, the first is preferred. This is semantically
equivalent to
>WORD 2>&1
-Here Documents
---------------
+3.6.5 Here Documents
+--------------------
- This type of redirection instructs the shell to read input from the
+This type of redirection instructs the shell to read input from the
current source until a line containing only WORD (with no trailing
blanks) is seen. All of the lines read up to that point are then used
as the standard input for a command.
- The format of here-documents is as follows:
+ The format of here-documents is:
<<[-]WORD
HERE-DOCUMENT
DELIMITER
DELIMITER. This allows here-documents within shell scripts to be
indented in a natural fashion.
-Duplicating File Descriptors
-----------------------------
+3.6.6 Here Strings
+------------------
+
+A variant of here documents, the format is:
+ <<< WORD
+
+ The WORD is expanded and supplied to the command on its standard
+input.
- The redirection operator
- [n]<&WORD
+3.6.7 Duplicating File Descriptors
+----------------------------------
-is used to duplicate input file descriptors. If WORD expands to one or
-more digits, the file descriptor denoted by `n' is made to be a copy of
-that file descriptor. If the digits in WORD do not specify a file
+The redirection operator
+ [N]<&WORD
+ is used to duplicate input file descriptors. If WORD expands to one
+or more digits, the file descriptor denoted by N is made to be a copy
+of that file descriptor. If the digits in WORD do not specify a file
descriptor open for input, a redirection error occurs. If WORD
-evaluates to `-', file descriptor `n' is closed. If `n' is not
-specified, the standard input (file descriptor 0) is used.
+evaluates to `-', file descriptor N is closed. If N is not specified,
+the standard input (file descriptor 0) is used.
The operator
- [n]>&WORD
-
-is used similarly to duplicate output file descriptors. If `n' is not
+ [N]>&WORD
+ is used similarly to duplicate output file descriptors. If N is not
specified, the standard output (file descriptor 1) is used. If the
digits in WORD do not specify a file descriptor open for output, a
-redirection error occurs. As a special case, if `n' is omitted, and
-WORD does not expand to one or more digits, the standard output and
-standard error are redirected as described previously.
+redirection error occurs. As a special case, if N is omitted, and WORD
+does not expand to one or more digits, the standard output and standard
+error are redirected as described previously.
-Opening File Descriptors for Reading and Writing
-------------------------------------------------
+3.6.8 Moving File Descriptors
+-----------------------------
- The redirection operator
- [n]<>WORD
+The redirection operator
+ [N]<&DIGIT-
+ moves the file descriptor DIGIT to file descriptor N, or the
+standard input (file descriptor 0) if N is not specified. DIGIT is
+closed after being duplicated to N.
-causes the file whose name is the expansion of WORD to be opened for
-both reading and writing on file descriptor `n', or on file descriptor
-0 if `n' is not specified. If the file does not exist, it is created.
+ Similarly, the redirection operator
+ [N]>&DIGIT-
+ moves the file descriptor DIGIT to file descriptor N, or the
+standard output (file descriptor 1) if N is not specified.
+
+3.6.9 Opening File Descriptors for Reading and Writing
+------------------------------------------------------
+
+The redirection operator
+ [N]<>WORD
+ causes the file whose name is the expansion of WORD to be opened for
+both reading and writing on file descriptor N, or on file descriptor 0
+if N is not specified. If the file does not exist, it is created.
\1f
File: bashref.info, Node: Executing Commands, Next: Shell Scripts, Prev: Redirections, Up: Basic Shell Features
-Executing Commands
-==================
+3.7 Executing Commands
+======================
* Menu:
\1f
File: bashref.info, Node: Simple Command Expansion, Next: Command Search and Execution, Up: Executing Commands
-Simple Command Expansion
-------------------------
+3.7.1 Simple Command Expansion
+------------------------------
- When a simple command is executed, the shell performs the following
+When a simple command is executed, the shell performs the following
expansions, assignments, and redirections, from left to right.
1. The words that the parser has marked as variable assignments (those
processing.
2. The words that are not variable assignments or redirections are
- expanded (*note Shell Expansions::.). If any words remain after
+ expanded (*note Shell Expansions::). If any words remain after
expansion, the first word is taken to be the name of the command
and the remaining words are the arguments.
3. Redirections are performed as described above (*note
- Redirections::.).
+ Redirections::).
4. The text after the `=' in each variable assignment undergoes tilde
expansion, parameter expansion, command substitution, arithmetic
\1f
File: bashref.info, Node: Command Search and Execution, Next: Command Execution Environment, Prev: Simple Command Expansion, Up: Executing Commands
-Command Search and Execution
-----------------------------
+3.7.2 Command Search and Execution
+----------------------------------
- After a command has been split into words, if it results in a simple
+After a command has been split into words, if it results in a simple
command and an optional list of arguments, the following actions are
taken.
\1f
File: bashref.info, Node: Command Execution Environment, Next: Environment, Prev: Command Search and Execution, Up: Executing Commands
-Command Execution Environment
------------------------------
+3.7.3 Command Execution Environment
+-----------------------------------
- The shell has an EXECUTION ENVIRONMENT, which consists of the
-following:
+The shell has an EXECUTION ENVIRONMENT, which consists of the following:
* open files inherited by the shell at invocation, as modified by
redirections supplied to the `exec' builtin
* options enabled by `shopt'
- * shell aliases defined with `alias' (*note Aliases::.)
+ * shell aliases defined with `alias' (*note Aliases::)
* various process IDs, including those of background jobs (*note
- Lists::.), the value of `$$', and the value of `$PPID'
+ Lists::), the value of `$$', and the value of `$PPID'
+
When a simple command other than a builtin or shell function is to
be executed, it is invoked in a separate execution environment that
* the file creation mode mask
- * shell variables marked for export, along with variables exported
- for the command, passed in the environment (*note Environment::.)
+ * shell variables and functions marked for export, along with
+ variables exported for the command, passed in the environment
+ (*note Environment::)
* traps caught by the shell are reset to the values inherited from
the shell's parent, and traps ignored by the shell are ignored
+
A command invoked in this separate environment cannot affect the
shell's execution environment.
- Command substitution and asynchronous commands are invoked in a
-subshell environment that is a duplicate of the shell environment,
-except that traps caught by the shell are reset to the values that the
-shell inherited from its parent at invocation. Builtin commands that
-are invoked as part of a pipeline are also executed in a subshell
-environment. Changes made to the subshell environment cannot affect
-the shell's execution environment.
+ Command substitution, commands grouped with parentheses, and
+asynchronous commands are invoked in a subshell environment that is a
+duplicate of the shell environment, except that traps caught by the
+shell are reset to the values that the shell inherited from its parent
+at invocation. Builtin commands that are invoked as part of a pipeline
+are also executed in a subshell environment. Changes made to the
+subshell environment cannot affect the shell's execution environment.
+
+ If a command is followed by a `&' and job control is not active, the
+default standard input for the command is the empty file `/dev/null'.
+Otherwise, the invoked command inherits the file descriptors of the
+calling shell as modified by redirections.
\1f
File: bashref.info, Node: Environment, Next: Exit Status, Prev: Command Execution Environment, Up: Executing Commands
-Environment
------------
+3.7.4 Environment
+-----------------
- When a program is invoked it is given an array of strings called the
+When a program is invoked it is given an array of strings called the
ENVIRONMENT. This is a list of name-value pairs, of the form
`name=value'.
*Note Shell Parameters::. These assignment statements affect only the
environment seen by that command.
- If the `-k' option is set (*note The Set Builtin::.), then all
+ If the `-k' option is set (*note The Set Builtin::), then all
parameter assignments are placed in the environment for a command, not
just those that precede the command name.
\1f
File: bashref.info, Node: Exit Status, Next: Signals, Prev: Environment, Up: Executing Commands
-Exit Status
------------
+3.7.5 Exit Status
+-----------------
- For the shell's purposes, a command which exits with a zero exit
-status has succeeded. A non-zero exit status indicates failure. This
+For the shell's purposes, a command which exits with a zero exit status
+has succeeded. A non-zero exit status indicates failure. This
seemingly counter-intuitive scheme is used so there is one well-defined
way to indicate success and a variety of ways to indicate various
failure modes. When a command terminates on a fatal signal whose
redirection, the exit status is greater than zero.
The exit status is used by the Bash conditional commands (*note
-Conditional Constructs::.) and some of the list constructs (*note
-Lists::.).
+Conditional Constructs::) and some of the list constructs (*note
+Lists::).
All of the Bash builtins return an exit status of zero if they
succeed and a non-zero status on failure, so they may be used by the
\1f
File: bashref.info, Node: Signals, Prev: Exit Status, Up: Executing Commands
-Signals
--------
+3.7.6 Signals
+-------------
- When Bash is interactive, in the absence of any traps, it ignores
+When Bash is interactive, in the absence of any traps, it ignores
`SIGTERM' (so that `kill 0' does not kill an interactive shell), and
`SIGINT' is caught and handled (so that the `wait' builtin is
interruptible). When Bash receives a `SIGINT', it breaks out of any
executing loops. In all cases, Bash ignores `SIGQUIT'. If job control
-is in effect (*note Job Control::.), Bash ignores `SIGTTIN', `SIGTTOU',
+is in effect (*note Job Control::), Bash ignores `SIGTTIN', `SIGTTOU',
and `SIGTSTP'.
- Commands started by Bash have signal handlers set to the values
-inherited by the shell from its parent. When job control is not in
-effect, asynchronous commands ignore `SIGINT' and `SIGQUIT' as well.
-Commands run as a result of command substitution ignore the
-keyboard-generated job control signals `SIGTTIN', `SIGTTOU', and
-`SIGTSTP'.
+ Non-builtin commands started by Bash have signal handlers set to the
+values inherited by the shell from its parent. When job control is not
+in effect, asynchronous commands ignore `SIGINT' and `SIGQUIT' in
+addition to these inherited handlers. Commands run as a result of
+command substitution ignore the keyboard-generated job control signals
+`SIGTTIN', `SIGTTOU', and `SIGTSTP'.
The shell exits by default upon receipt of a `SIGHUP'. Before
-exiting, it resends the `SIGHUP' to all jobs, running or stopped.
-Stopped jobs are sent `SIGCONT' to ensure that they receive the
-`SIGHUP'. To prevent the shell from sending the `SIGHUP' signal to a
-particular job, it should be removed from the jobs table with the
-`disown' builtin (*note Job Control Builtins::.) or marked to not
+exiting, an interactive shell resends the `SIGHUP' to all jobs, running
+or stopped. Stopped jobs are sent `SIGCONT' to ensure that they receive
+the `SIGHUP'. To prevent the shell from sending the `SIGHUP' signal to
+a particular job, it should be removed from the jobs table with the
+`disown' builtin (*note Job Control Builtins::) or marked to not
receive `SIGHUP' using `disown -h'.
If the `huponexit' shell option has been set with `shopt' (*note
-Bash Builtins::.), Bash sends a `SIGHUP' to all jobs when an
-interactive login shell exits.
+Bash Builtins::), Bash sends a `SIGHUP' to all jobs when an interactive
+login shell exits.
- When Bash receives a signal for which a trap has been set while
-waiting for a command to complete, the trap will not be executed until
-the command completes. When Bash is waiting for an asynchronous
-command via the `wait' builtin, the reception of a signal for which a
-trap has been set will cause the `wait' builtin to return immediately
-with an exit status greater than 128, immediately after which the trap
-is executed.
+ If Bash is waiting for a command to complete and receives a signal
+for which a trap has been set, the trap will not be executed until the
+command completes. When Bash is waiting for an asynchronous command
+via the `wait' builtin, the reception of a signal for which a trap has
+been set will cause the `wait' builtin to return immediately with an
+exit status greater than 128, immediately after which the trap is
+executed.
\1f
File: bashref.info, Node: Shell Scripts, Prev: Executing Commands, Up: Basic Shell Features
-Shell Scripts
-=============
+3.8 Shell Scripts
+=================
- A shell script is a text file containing shell commands. When such
-a file is used as the first non-option argument when invoking Bash, and
-neither the `-c' nor `-s' option is supplied (*note Invoking Bash::.),
+A shell script is a text file containing shell commands. When such a
+file is used as the first non-option argument when invoking Bash, and
+neither the `-c' nor `-s' option is supplied (*note Invoking Bash::),
Bash reads and executes commands from the file, then exits. This mode
-of operation creates a non-interactive shell. When Bash runs a shell
-script, it sets the special parameter `0' to the name of the file,
-rather than the name of the shell, and the positional parameters are
-set to the remaining arguments, if any are given. If no additional
-arguments are supplied, the positional parameters are unset.
+of operation creates a non-interactive shell. The shell first searches
+for the file in the current directory, and looks in the directories in
+`$PATH' if not found there.
+
+ When Bash runs a shell script, it sets the special parameter `0' to
+the name of the file, rather than the name of the shell, and the
+positional parameters are set to the remaining arguments, if any are
+given. If no additional arguments are supplied, the positional
+parameters are unset.
A shell script may be made executable by using the `chmod' command
to turn on the execute bit. When Bash finds such a file while
searching the `$PATH' for a command, it spawns a subshell to execute
it. In other words, executing
filename ARGUMENTS
-
-is equivalent to executing
+ is equivalent to executing
bash filename ARGUMENTS
if `filename' is an executable shell script. This subshell
\1f
File: bashref.info, Node: Shell Builtin Commands, Next: Shell Variables, Prev: Basic Shell Features, Up: Top
-Shell Builtin Commands
-**********************
+4 Shell Builtin Commands
+************************
* Menu:
Builtin commands are contained within the shell itself. When the
name of a builtin command is used as the first word of a simple command
-(*note Simple Commands::.), the shell executes the command directly,
+(*note Simple Commands::), the shell executes the command directly,
without invoking another program. Builtin commands are necessary to
implement functionality impossible or inconvenient to obtain with
separate utilities.
Several builtin commands are described in other chapters: builtin
commands which provide the Bash interface to the job control facilities
-(*note Job Control Builtins::.), the directory stack (*note Directory
-Stack Builtins::.), the command history (*note Bash History
-Builtins::.), and the programmable completion facilities (*note
-Programmable Completion Builtins::.).
+(*note Job Control Builtins::), the directory stack (*note Directory
+Stack Builtins::), the command history (*note Bash History Builtins::),
+and the programmable completion facilities (*note Programmable
+Completion Builtins::).
Many of the builtins have been extended by POSIX or Bash.
+ Unless otherwise noted, each builtin command documented as accepting
+options preceded by `-' accepts `--' to signify the end of the options.
+
\1f
File: bashref.info, Node: Bourne Shell Builtins, Next: Bash Builtins, Up: Shell Builtin Commands
-Bourne Shell Builtins
-=====================
+4.1 Bourne Shell Builtins
+=========================
- The following shell builtin commands are inherited from the Bourne
+The following shell builtin commands are inherited from the Bourne
Shell. These commands are implemented as specified by the POSIX 1003.2
standard.
. FILENAME [ARGUMENTS]
Read and execute commands from the FILENAME argument in the
current shell context. If FILENAME does not contain a slash, the
- `PATH' variable is used to find FILENAME. The current directory
- is searched if FILENAME is not found in `$PATH'. If any ARGUMENTS
- are supplied, they become the positional parameters when FILENAME
- is executed. Otherwise the positional parameters are unchanged.
- The return status is the exit status of the last command executed,
- or zero if no commands are executed. If FILENAME is not found, or
- cannot be read, the return status is non-zero. This builtin is
- equivalent to `source'.
+ `PATH' variable is used to find FILENAME. When Bash is not in
+ POSIX mode, the current directory is searched if FILENAME is not
+ found in `$PATH'. If any ARGUMENTS are supplied, they become the
+ positional parameters when FILENAME is executed. Otherwise the
+ positional parameters are unchanged. The return status is the
+ exit status of the last command executed, or zero if no commands
+ are executed. If FILENAME is not found, or cannot be read, the
+ return status is non-zero. This builtin is equivalent to `source'.
`break'
break [N]
greater than or equal to 1.
`cd'
- cd [-LP] [DIRECTORY]
+ cd [-L|-P] [DIRECTORY]
Change the current working directory to DIRECTORY. If DIRECTORY
is not given, the value of the `HOME' shell variable is used. If
the shell variable `CDPATH' exists, it is used as a search path.
- If DIRECTORY begins with a slash, `CDPATH' is not used. The `-P'
- option means to not follow symbolic links; symbolic links are
- followed by default or with the `-L' option. If DIRECTORY is `-',
- it is equivalent to `$OLDPWD'. The return status is zero if the
- directory is successfully changed, non-zero otherwise.
+ If DIRECTORY begins with a slash, `CDPATH' is not used.
+
+ The `-P' option means to not follow symbolic links; symbolic links
+ are followed by default or with the `-L' option. If DIRECTORY is
+ `-', it is equivalent to `$OLDPWD'.
+
+ If a non-empty directory name from `CDPATH' is used, or if `-' is
+ the first argument, and the directory change is successful, the
+ absolute pathname of the new working directory is written to the
+ standard output.
+
+ The return status is zero if the directory is successfully changed,
+ non-zero otherwise.
`continue'
continue [N]
option means to no longer mark each NAME for export. If no NAMES
are supplied, or if the `-p' option is given, a list of exported
names is displayed. The `-p' option displays output in a form
- that may be reused as input. The return status is zero unless an
- invalid option is supplied, one of the names is not a valid shell
- variable name, or `-f' is supplied with a name that is not a shell
- function.
+ that may be reused as input. If a variable name is followed by
+ =VALUE, the value of the variable is set to VALUE.
+
+ The return status is zero unless an invalid option is supplied,
+ one of the names is not a valid shell variable name, or `-f' is
+ supplied with a name that is not a shell function.
`getopts'
getopts OPTSTRING NAME [ARGS]
character found.
`hash'
- hash [-r] [-p FILENAME] [NAME]
+ hash [-'r] [-p FILENAME] [-dt] [NAME]
Remember the full pathnames of commands specified as NAME
arguments, so they need not be searched for on subsequent
invocations. The commands are found by searching through the
directories listed in `$PATH'. The `-p' option inhibits the path
search, and FILENAME is used as the location of NAME. The `-r'
- option causes the shell to forget all remembered locations. If no
- arguments are given, information about remembered commands is
- printed. The return status is zero unless a NAME is not found or
- an invalid option is supplied.
+ option causes the shell to forget all remembered locations. The
+ `-d' option causes the shell to forget the remembered location of
+ each NAME. If the `-t' option is supplied, the full pathname to
+ which each NAME corresponds is printed. If multiple NAME
+ arguments are supplied with `-t' the NAME is printed before the
+ hashed full pathname. The `-l' option causes output to be
+ displayed in a format that may be reused as input. If no
+ arguments are given, or if only `-l' is supplied, information
+ about remembered commands is printed. The return status is zero
+ unless a NAME is not found or an invalid option is supplied.
`pwd'
pwd [-LP]
current directory or an invalid option is supplied.
`readonly'
- readonly [-apf] [NAME] ...
+ readonly [-apf] [NAME[=VALUE]] ...
Mark each NAME as readonly. The values of these names may not be
changed by subsequent assignment. If the `-f' option is supplied,
each NAME refers to a shell function. The `-a' option means each
NAME refers to an array variable. If no NAME arguments are given,
or if the `-p' option is supplied, a list of all readonly names is
printed. The `-p' option causes output to be displayed in a
- format that may be reused as input. The return status is zero
- unless an invalid option is supplied, one of the NAME arguments is
- not a valid shell variable or function name, or the `-f' option is
- supplied with a name that is not a shell function.
+ format that may be reused as input. If a variable name is
+ followed by =VALUE, the value of the variable is set to VALUE.
+ The return status is zero unless an invalid option is supplied,
+ one of the NAME arguments is not a valid shell variable or
+ function name, or the `-f' option is supplied with a name that is
+ not a shell function.
`return'
return [N]
terminate execution of a script being executed with the `.' (or
`source') builtin, returning either N or the exit status of the
last command executed within the script as the exit status of the
- script. The return status is false if `return' is used outside a
- function and not during the execution of a script by `.' or
- `source'.
+ script. Any command associated with the `RETURN' trap is executed
+ before execution resumes after the function or script. The return
+ status is non-zero if `return' is used outside a function and not
+ during the execution of a script by `.' or `source'.
`shift'
shift [N]
If the first argument is `!', the expression is true if and
only if the second argument is null. If the first argument
is one of the unary conditional operators (*note Bash
- Conditional Expressions::.), the expression is true if the
+ Conditional Expressions::), the expression is true if the
unary test is true. If the first argument is not a valid
unary operator, the expression is false.
3 arguments
If the second argument is one of the binary conditional
- operators (*note Bash Conditional Expressions::.), the result
+ operators (*note Bash Conditional Expressions::), the result
of the expression is the result of the binary test using the
first and third arguments as operands. If the first argument
is `!', the value is the negation of the two-argument test
`trap'
trap [-lp] [ARG] [SIGSPEC ...]
The commands in ARG are to be read and executed when the shell
- receives signal SIGSPEC. If ARG is absent or equal to `-', all
- specified signals are reset to the values they had when the shell
- was started. If ARG is the null string, then the signal specified
- by each SIGSPEC is ignored by the shell and commands it invokes.
- If ARG is not present and `-p' has been supplied, the shell
- displays the trap commands associated with each SIGSPEC. If no
- arguments are supplied, or only `-p' is given, `trap' prints the
- list of commands associated with each signal number in a form that
- may be reused as shell input. Each SIGSPEC is either a signal
- name such as `SIGINT' (with or without the `SIG' prefix) or a
- signal number. If a SIGSPEC is `0' or `EXIT', ARG is executed
- when the shell exits. If a SIGSPEC is `DEBUG', the command ARG is
- executed after every simple command. The `-l' option causes the
- shell to print a list of signal names and their corresponding
- numbers.
+ receives signal SIGSPEC. If ARG is absent (and there is a single
+ SIGSPEC) or equal to `-', each specified signal's disposition is
+ reset to the value it had when the shell was started. If ARG is
+ the null string, then the signal specified by each SIGSPEC is
+ ignored by the shell and commands it invokes. If ARG is not
+ present and `-p' has been supplied, the shell displays the trap
+ commands associated with each SIGSPEC. If no arguments are
+ supplied, or only `-p' is given, `trap' prints the list of commands
+ associated with each signal number in a form that may be reused as
+ shell input. The `-l' option causes the shell to print a list of
+ signal names and their corresponding numbers. Each SIGSPEC is
+ either a signal name or a signal number. Signal names are case
+ insensitive and the `SIG' prefix is optional. If a SIGSPEC is `0'
+ or `EXIT', ARG is executed when the shell exits. If a SIGSPEC is
+ `DEBUG', the command ARG is executed before every simple command,
+ `for' command, `case' command, `select' command, every arithmetic
+ `for' command, and before the first command executes in a shell
+ function. Refer to the description of the `extglob' option to the
+ `shopt' builtin (*note Bash Builtins::) for details of its effect
+ on the `DEBUG' trap. If a SIGSPEC is `ERR', the command ARG is
+ executed whenever a simple command has a non-zero exit status,
+ subject to the following conditions. The `ERR' trap is not
+ executed if the failed command is part of the command list
+ immediately following an `until' or `while' keyword, part of the
+ test in an `if' statement, part of a `&&' or `||' list, or if the
+ command's return status is being inverted using `!'. These are
+ the same conditions obeyed by the `errexit' option. If a SIGSPEC
+ is `RETURN', the command ARG is executed each time a shell
+ function or a script executed with the `.' or `source' builtins
+ finishes executing.
Signals ignored upon entry to the shell cannot be trapped or reset.
Trapped signals are reset to their original values in a child
variable. If the `-f' option is given, the NAMEs refer to shell
functions, and the function definition is removed. Readonly
variables and functions may not be unset. The return status is
- zero unless a NAME does not exist or is readonly.
+ zero unless a NAME is readonly.
\1f
File: bashref.info, Node: Bash Builtins, Next: The Set Builtin, Prev: Bourne Shell Builtins, Up: Shell Builtin Commands
-Bash Builtin Commands
-=====================
+4.2 Bash Builtin Commands
+=========================
- This section describes builtin commands which are unique to or have
+This section describes builtin commands which are unique to or have
been extended in Bash. Some of these commands are specified in the
POSIX 1003.2 standard.
bind [-m KEYMAP] -f FILENAME
bind [-m KEYMAP] -x KEYSEQ:SHELL-COMMAND
bind [-m KEYMAP] KEYSEQ:FUNCTION-NAME
-
- Display current Readline (*note Command Line Editing::.) key and
- function bindings, or bind a key sequence to a Readline function
- or macro. The binding syntax accepted is identical to that of a
- Readline initialization file (*note Readline Init File::.), but
- each binding must be passed as a separate argument: e.g.,
+ bind READLINE-COMMAND
+
+ Display current Readline (*note Command Line Editing::) key and
+ function bindings, bind a key sequence to a Readline function or
+ macro, or set a Readline variable. Each non-option argument is a
+ command as it would appear in a a Readline initialization file
+ (*note Readline Init File::), but each binding or command must be
+ passed as a separate argument; e.g.,
`"\C-x\C-r":re-read-init-file'. Options, if supplied, have the
following meanings:
`-m KEYMAP'
Use KEYMAP as the keymap to be affected by the subsequent
bindings. Acceptable KEYMAP names are `emacs',
- `emacs-standard', `emacs-meta', `emacs-ctlx', `vi',
+ `emacs-standard', `emacs-meta', `emacs-ctlx', `vi', `vi-move',
`vi-command', and `vi-insert'. `vi' is equivalent to
`vi-command'; `emacs' is equivalent to `emacs-standard'.
`-x KEYSEQ:SHELL-COMMAND'
Cause SHELL-COMMAND to be executed whenever KEYSEQ is entered.
+
The return status is zero unless an invalid option is supplied or
an error occurs.
within the function. The return status is non-zero if
SHELL-BUILTIN is not a shell builtin command.
+`caller'
+ caller [EXPR]
+ Returns the context of any active subroutine call (a shell
+ function or a script executed with the `.' or `source' builtins).
+
+ Without EXPR, `caller' displays the line number and source
+ filename of the current subroutine call. If a non-negative
+ integer is supplied as EXPR, `caller' displays the line number,
+ subroutine name, and source file corresponding to that position in
+ the current execution call stack. This extra information may be
+ used, for example, to print a stack trace. The current frame is
+ frame 0.
+
+ The return value is 0 unless the shell is not executing a
+ subroutine call or EXPR does not correspond to a valid position in
+ the call stack.
+
`command'
command [-pVv] COMMAND [ARGUMENTS ...]
Runs COMMAND with ARGUMENTS ignoring any shell function named
named `ls', running `command ls' within the function will execute
the external command `ls' instead of calling the function
recursively. The `-p' option means to use a default value for
- `$PATH' that is guaranteed to find all of the standard utilities.
+ `PATH' that is guaranteed to find all of the standard utilities.
The return status in this case is 127 if COMMAND cannot be found
or an error occurred, and the exit status of COMMAND otherwise.
non-zero if not.
`declare'
- declare [-afFrxi] [-p] [NAME[=VALUE]]
+ declare [-afFirtx] [-p] [NAME[=VALUE] ...]
Declare variables and give them attributes. If no NAMEs are
given, then display the values of variables instead.
The `-p' option will display the attributes and values of each
NAME. When `-p' is used, additional options are ignored. The
`-F' option inhibits the display of function definitions; only the
- function name and attributes are printed. `-F' implies `-f'. The
- following options can be used to restrict output to variables with
- the specified attributes or to give variables attributes:
+ function name and attributes are printed. If the `extdebug' shell
+ option is enabled using `shopt' (*note Bash Builtins::), the
+ source file name and line number where the function is defined are
+ displayed as well. `-F' implies `-f'. The following options can
+ be used to restrict output to variables with the specified
+ attributes or to give variables attributes:
`-a'
- Each NAME is an array variable (*note Arrays::.).
+ Each NAME is an array variable (*note Arrays::).
`-f'
Use function names only.
`-i'
The variable is to be treated as an integer; arithmetic
- evaluation (*note Shell Arithmetic::.) is performed when the
+ evaluation (*note Shell Arithmetic::) is performed when the
variable is assigned a value.
`-r'
Make NAMEs readonly. These names cannot then be assigned
values by subsequent assignment statements or unset.
+ `-t'
+ Give each NAME the `trace' attribute. Traced functions
+ inherit the `DEBUG' trap from the calling shell. The trace
+ attribute has no special meaning for variables.
+
`-x'
Mark each NAME for export to subsequent commands via the
environment.
Using `+' instead of `-' turns off the attribute instead. When
used in a function, `declare' makes each NAME local, as with the
- `local' command.
+ `local' command. If a variable name is followed by =VALUE, the
+ value of the variable is set to VALUE.
The return status is zero unless an invalid option is encountered,
an attempt is made to define a function using `-f foo=bar', an
attempt is made to assign a value to a readonly variable, an
attempt is made to assign a value to an array variable without
- using the compound assignment syntax (*note Arrays::.), one of the
+ using the compound assignment syntax (*note Arrays::), one of the
NAMES is not a valid shell variable name, an attempt is made to
turn off readonly status for a readonly variable, an attempt is
made to turn off array status for an array variable, or an attempt
`\\'
backslash
+ `\0NNN'
+ the eight-bit character whose value is the octal value NNN
+ (zero to three octal digits)
+
`\NNN'
- the character whose `ASCII' code is the octal value NNN (one
- to three digits)
+ the eight-bit character whose value is the octal value NNN
+ (one to three octal digits)
- `\xNNN'
- the character whose `ASCII' code is the hexadecimal value NNN
- (one to three digits)
+ `\xHH'
+ the eight-bit character whose value is the hexadecimal value
+ HH (one or two hex digits)
`enable'
enable [-n] [-p] [-f FILENAME] [-ads] [NAME ...]
If there are no options, a list of the shell builtins is displayed.
The `-s' option restricts `enable' to the POSIX special builtins.
If `-s' is used with `-f', the new builtin becomes a special
- builtin (*note Special Builtins::.).
+ builtin (*note Special Builtins::).
The return status is zero unless a NAME is not a shell builtin or
there is an error loading a new builtin from a shared object.
evaluates to 0, `let' returns 1; otherwise 0 is returned.
`local'
- local [OPTION] NAME[=VALUE]
+ local [OPTION] NAME[=VALUE] ...
For each argument, a local variable named NAME is created, and
assigned VALUE. The OPTION can be any of the options accepted by
`declare'. `local' can only be used within a function; it makes
specifications, each of which causes printing of the next
successive ARGUMENT. In addition to the standard `printf(1)'
formats, `%b' causes `printf' to expand backslash escape sequences
- in the corresponding ARGUMENT, and `%q' causes `printf' to output
- the corresponding ARGUMENT in a format that can be reused as shell
- input.
+ in the corresponding ARGUMENT, (except that `\c' terminates
+ output, backslashes in `\'', `\"', and `\?' are not removed, and
+ octal escapes beginning with `\0' may contain up to four digits),
+ and `%q' causes `printf' to output the corresponding ARGUMENT in a
+ format that can be reused as shell input.
The FORMAT is reused as necessary to consume all of the ARGUMENTS.
If the FORMAT requires more ARGUMENTS than are supplied, the extra
success, non-zero on failure.
`read'
- read [-ers] [-a ANAME] [-p PROMPT] [-t TIMEOUT] [-n NCHARS] [-d DELIM] [NAME ...]
- One line is read from the standard input, and the first word is
- assigned to the first NAME, the second word to the second NAME,
- and so on, with leftover words and their intervening separators
- assigned to the last NAME. If there are fewer words read from the
- standard input than names, the remaining names are assigned empty
- values. The characters in the value of the `IFS' variable are
- used to split the line into words. The backslash character `\'
- may be used to remove any special meaning for the next character
- read and for line continuation. If no names are supplied, the
- line read is assigned to the variable `REPLY'. The return code is
- zero, unless end-of-file is encountered or `read' times out.
- Options, if supplied, have the following meanings:
+ read [-ers] [-a ANAME] [-d DELIM] [-n NCHARS] [-p PROMPT] [-t TIMEOUT] [-u FD] [NAME ...]
+ One line is read from the standard input, or from the file
+ descriptor FD supplied as an argument to the `-u' option, and the
+ first word is assigned to the first NAME, the second word to the
+ second NAME, and so on, with leftover words and their intervening
+ separators assigned to the last NAME. If there are fewer words
+ read from the input stream than names, the remaining names are
+ assigned empty values. The characters in the value of the `IFS'
+ variable are used to split the line into words. The backslash
+ character `\' may be used to remove any special meaning for the
+ next character read and for line continuation. If no names are
+ supplied, the line read is assigned to the variable `REPLY'. The
+ return code is zero, unless end-of-file is encountered, `read'
+ times out, or an invalid file descriptor is supplied as the
+ argument to `-u'. Options, if supplied, have the following
+ meanings:
`-a ANAME'
The words are assigned to sequential indices of the array
line, rather than newline.
`-e'
- Readline (*note Command Line Editing::.) is used to obtain
- the line.
+ Readline (*note Command Line Editing::) is used to obtain the
+ line.
`-n NCHARS'
`read' returns after reading NCHARS characters rather than
option has no effect if `read' is not reading input from the
terminal or a pipe.
+ `-u FD'
+ Read input from file descriptor FD.
+
+
`shopt'
shopt [-pqsu] [-o] [OPTNAME ...]
Toggle the values of variables controlling optional shell behavior.
`-o'
Restricts the values of OPTNAME to be those defined for the
- `-o' option to the `set' builtin (*note The Set Builtin::.).
+ `-o' option to the `set' builtin (*note The Set Builtin::).
If either `-s' or `-u' is used with no OPTNAME arguments, the
display is limited to those options which are set or unset,
*Note Aliases::. This option is enabled by default for
interactive shells.
+ `extdebug'
+ If set, behavior intended for use by debuggers is enabled:
+
+ 1. The `-F' option to the `declare' builtin (*note Bash
+ Builtins::) displays the source file name and line
+ number corresponding to each function name supplied as
+ an argument.
+
+ 2. If the command run by the `DEBUG' trap returns a
+ non-zero value, the next command is skipped and not
+ executed.
+
+ 3. If the command run by the `DEBUG' trap returns a value
+ of 2, and the shell is executing in a subroutine (a
+ shell function or a shell script executed by the `.' or
+ `source' builtins), a call to `return' is simulated.
+
`extglob'
If set, the extended pattern matching features described above
- (*note Pattern Matching::.) are enabled.
+ (*note Pattern Matching::) are enabled.
+
+ `extquote'
+ If set, `$'STRING'' and `$"STRING"' quoting is performed
+ within `${PARAMETER}' expansions enclosed in double quotes.
+ This option is enabled by default.
+
+ `failglob'
+ If set, patterns which fail to match filenames during
+ pathname expansion result in an expansion error.
+
+ `force_fignore'
+ If set, the suffixes specified by the `FIGNORE' shell variable
+ cause words to be ignored when performing word completion
+ even if the ignored words are the only possible completions.
+ *Note Bash Variables::, for a description of `FIGNORE'. This
+ option is enabled by default.
+
+ `gnu_errfmt'
+ If set, shell error messages are written in the standard GNU
+ error message format.
`histappend'
If set, the history list is appended to the file named by the
`hostcomplete'
If set, and Readline is being used, Bash will attempt to
perform hostname completion when a word containing a `@' is
- being completed (*note Commands For Completion::.). This
+ being completed (*note Commands For Completion::). This
option is enabled by default.
`huponexit'
If set, Bash will send `SIGHUP' to all jobs when an
- interactive login shell exits (*note Signals::.).
+ interactive login shell exits (*note Signals::).
`interactive_comments'
Allow a word beginning with `#' to cause that word and all
commands are saved to the history with embedded newlines
rather than using semicolon separators where possible.
+ `login_shell'
+ The shell sets this option if it is started as a login shell
+ (*note Invoking Bash::). The value may not be changed.
+
`mailwarn'
If set, and a file that Bash is checking for mail has been
accessed since the last time it was checked, the message
`progcomp'
If set, the programmable completion facilities (*note
- Programmable Completion::.) are enabled. This option is
+ Programmable Completion::) are enabled. This option is
enabled by default.
`promptvars'
- If set, prompt strings undergo variable and parameter
- expansion after being expanded (*note Printing a Prompt::.).
+ If set, prompt strings undergo parameter expansion, command
+ substitution, arithmetic expansion, and quote removal after
+ being expanded as described below (*note Printing a Prompt::).
This option is enabled by default.
`restricted_shell'
The shell sets this option if it is started in restricted mode
- (*note The Restricted Shell::.). The value may not be
- changed. This is not reset when the startup files are
- executed, allowing the startup files to discover whether or
- not a shell is restricted.
+ (*note The Restricted Shell::). The value may not be changed.
+ This is not reset when the startup files are executed,
+ allowing the startup files to discover whether or not a shell
+ is restricted.
`shift_verbose'
If this is set, the `shift' builtin prints an error message
If set, the `echo' builtin expands backslash-escape sequences
by default.
+
The return status when listing options is zero if all OPTNAMES are
enabled, non-zero otherwise. When setting or unsetting options,
the return status is zero unless an OPTNAME is not a valid shell
`source'
source FILENAME
- A synonym for `.' (*note Bourne Shell Builtins::.).
+ A synonym for `.' (*note Bourne Shell Builtins::).
`type'
- type [-atp] [NAME ...]
+ type [-afptP] [NAME ...]
For each NAME, indicate how it would be interpreted if used as a
command name.
disk file that would be executed, or nothing if `-t' would not
return `file'.
+ The `-P' option forces a path search for each NAME, even if `-t'
+ would not return `file'.
+
+ If a command is hashed, `-p' and `-P' print the hashed value, not
+ necessarily the file that appears first in `$PATH'.
+
If the `-a' option is used, `type' returns all of the places that
contain an executable named FILE. This includes aliases and
functions, if and only if the `-p' option is not also used.
+ If the `-f' option is used, `type' does not attempt to find shell
+ functions, as with the `command' builtin.
+
The return status is zero if any of the NAMES are found, non-zero
if none are found.
`typeset'
- typeset [-afFrxi] [-p] [NAME[=VALUE]]
+ typeset [-afFrxi] [-p] [NAME[=VALUE] ...]
The `typeset' command is supplied for compatibility with the Korn
shell; however, it has been deprecated in favor of the `declare'
builtin command.
`-v'
The maximum amount of virtual memory available to the process.
- If LIMIT is given, it is the new value of the specified resource.
- Otherwise, the current value of the soft limit for the specified
- resource is printed, unless the `-H' option is supplied. When
- setting new limits, if neither `-H' nor `-S' is supplied, both the
- hard and soft limits are set. If no option is given, then `-f' is
- assumed. Values are in 1024-byte increments, except for `-t',
- which is in seconds, `-p', which is in units of 512-byte blocks,
- and `-n' and `-u', which are unscaled values.
- The return status is zero unless an invalid option is supplied, a
- non-numeric argument other than `unlimited' is supplied as a
- LIMIT, or an error occurs while setting a new limit.
+ If LIMIT is given, it is the new value of the specified resource;
+ the special LIMIT values `hard', `soft', and `unlimited' stand for
+ the current hard limit, the current soft limit, and no limit,
+ respectively. Otherwise, the current value of the soft limit for
+ the specified resource is printed, unless the `-H' option is
+ supplied. When setting new limits, if neither `-H' nor `-S' is
+ supplied, both the hard and soft limits are set. If no option is
+ given, then `-f' is assumed. Values are in 1024-byte increments,
+ except for `-t', which is in seconds, `-p', which is in units of
+ 512-byte blocks, and `-n' and `-u', which are unscaled values.
+
+ The return status is zero unless an invalid option or argument is
+ supplied, or an error occurs while setting a new limit.
`unalias'
unalias [-a] [NAME ... ]
Remove each NAME from the list of aliases. If `-a' is supplied,
all aliases are removed. Aliases are described in *Note Aliases::.
+
\1f
File: bashref.info, Node: The Set Builtin, Next: Special Builtins, Prev: Bash Builtins, Up: Shell Builtin Commands
-The Set Builtin
-===============
+4.3 The Set Builtin
+===================
- This builtin is so complicated that it deserves its own section.
+This builtin is so complicated that it deserves its own section.
`set'
set [--abefhkmnptuvxBCHP] [-o OPTION] [ARGUMENT ...]
Options, if specified, have the following meanings:
`-a'
- Mark variables which are modified or created for export.
+ Mark variables and function which are modified or created for
+ export to the environment of subsequent commands.
`-b'
Cause the status of terminated background jobs to be reported
`-e'
Exit immediately if a simple command (*note Simple
- Commands::.) exits with a non-zero status, unless the command
- that fails is part of an `until' or `while' loop, part of an
- `if' statement, part of a `&&' or `||' list, or if the
- command's return status is being inverted using `!'.
+ Commands::) exits with a non-zero status, unless the command
+ that fails is part of the command list immediately following
+ a `while' or `until' keyword, part of the test in an `if'
+ statement, part of a `&&' or `||' list, or if the command's
+ return status is being inverted using `!'. A trap on `ERR',
+ if set, is executed before the shell exits.
`-f'
Disable file name generation (globbing).
the command name.
`-m'
- Job control is enabled (*note Job Control::.).
+ Job control is enabled (*note Job Control::).
`-n'
Read commands but do not execute them; this may be used to
`emacs'
Use an `emacs'-style line editing interface (*note
- Command Line Editing::.).
+ Command Line Editing::).
`errexit'
Same as `-e'.
+ `errtrace'
+ Same as `-E'.
+
+ `functrace'
+ Same as `-T'.
+
`hashall'
Same as `-h'.
`noglob'
Same as `-f'.
+ `nolog'
+ Currently ignored.
+
`notify'
Same as `-b'.
`physical'
Same as `-P'.
+ `pipefail'
+ If set, the return value of a pipeline is the value of
+ the last (rightmost) command to exit with a non-zero
+ status, or zero if all commands in the pipeline exit
+ successfully. This option is disabled by default.
+
`posix'
Change the behavior of Bash where the default operation
differs from the POSIX 1003.2 standard to match the
- standard (*note Bash POSIX Mode::.). This is intended
- to make Bash behave as a strict superset of that
- standard.
+ standard (*note Bash POSIX Mode::). This is intended to
+ make Bash behave as a strict superset of that standard.
`privileged'
Same as `-p'.
Print shell input lines as they are read.
`-x'
- Print a trace of simple commands and their arguments after
- they are expanded and before they are executed.
+ Print a trace of simple commands, \fBfor\fP commands,
+ \fBcase\fP commands, \fBselect\fP commands, and arithmetic
+ \fBfor\fP commands and their arguments or associated word
+ lists after they are expanded and before they are executed.
+ The value of the `PS4' variable is expanded and the resultant
+ value is printed before the command and its expanded
+ arguments.
`-B'
The shell will perform brace expansion (*note Brace
- Expansion::.). This option is on by default.
+ Expansion::). This option is on by default.
`-C'
Prevent output redirection using `>', `>&', and `<>' from
overwriting existing files.
+ `-E'
+ If set, any trap on `ERR' is inherited by shell functions,
+ command substitutions, and commands executed in a subshell
+ environment. The `ERR' trap is normally not inherited in
+ such cases.
+
`-H'
Enable `!' style history substitution (*note History
- Interaction::.). This option is on by default for
- interactive shells.
+ Interaction::). This option is on by default for interactive
+ shells.
`-P'
If set, do not follow symbolic links when performing commands
$ cd ..; pwd
/usr/local
+ `-T'
+ If set, any trap on `DEBUG' is inherited by shell functions,
+ command substitutions, and commands executed in a subshell
+ environment. The `DEBUG' trap is normally not inherited in
+ such cases.
+
`--'
If no arguments follow this option, then the positional
parameters are unset. Otherwise, the positional parameters
\1f
File: bashref.info, Node: Special Builtins, Prev: The Set Builtin, Up: Shell Builtin Commands
-Special Builtins
-================
+4.4 Special Builtins
+====================
- For historical reasons, the POSIX 1003.2 standard has classified
-several builtin commands as *special*. When Bash is executing in POSIX
+For historical reasons, the POSIX 1003.2 standard has classified
+several builtin commands as _special_. When Bash is executing in POSIX
mode, the special builtins differ from other builtin commands in three
respects:
\1f
File: bashref.info, Node: Shell Variables, Next: Bash Features, Prev: Shell Builtin Commands, Up: Top
-Shell Variables
-***************
+5 Shell Variables
+*****************
* Menu:
\1f
File: bashref.info, Node: Bourne Shell Variables, Next: Bash Variables, Up: Shell Variables
-Bourne Shell Variables
-======================
+5.1 Bourne Shell Variables
+==========================
- Bash uses certain shell variables in the same way as the Bourne
-shell. In some cases, Bash assigns a default value to the variable.
+Bash uses certain shell variables in the same way as the Bourne shell.
+In some cases, Bash assigns a default value to the variable.
`CDPATH'
A colon-separated list of directories used as a search path for
`HOME'
The current user's home directory; the default for the `cd' builtin
command. The value of this variable is also used by tilde
- expansion (*note Tilde Expansion::.).
+ expansion (*note Tilde Expansion::).
`IFS'
A list of characters that separate fields; used when the shell
`PATH'
A colon-separated list of directories in which the shell looks for
- commands.
+ commands. A zero-length (null) directory name in the value of
+ `PATH' indicates the current directory. A null directory name may
+ appear as two adjacent colons, or as an initial or trailing colon.
`PS1'
The primary prompt string. The default value is `\s-\v\$ '.
`PS2'
The secondary prompt string. The default value is `> '.
+
\1f
File: bashref.info, Node: Bash Variables, Prev: Bourne Shell Variables, Up: Shell Variables
-Bash Variables
-==============
+5.2 Bash Variables
+==================
- These variables are set or used by Bash, but other shells do not
+These variables are set or used by Bash, but other shells do not
normally treat them specially.
A few variables used by Bash are described in different chapters:
variables for controlling the job control facilities (*note Job Control
-Variables::.).
+Variables::).
`BASH'
The full pathname used to execute the current instance of Bash.
+`BASH_ARGC'
+ An array variable whose values are the number of parameters in each
+ frame of the current bash execution call stack. The number of
+ parameters to the current subroutine (shell function or script
+ executed with `.' or `source') is at the top of the stack. When a
+ subroutine is executed, the number of parameters passed is pushed
+ onto `BASH_ARGC'.
+
+`BASH_ARGV'
+ An array variable containing all of the parameters in the current
+ bash execution call stack. The final parameter of the last
+ subroutine call is at the top of the stack; the first parameter of
+ the initial call is at the bottom. When a subroutine is executed,
+ the parameters supplied are pushed onto `BASH_ARGV'.
+
+`BASH_COMMAND'
+ The command currently being executed or about to be executed,
+ unless the shell is executing a command as the result of a trap,
+ in which case it is the command executing at the time of the trap.
+
`BASH_ENV'
If this variable is set when Bash is invoked to execute a shell
script, its value is expanded and used as the name of a startup
file to read before executing the script. *Note Bash Startup
Files::.
-`BASH_VERSION'
- The version number of the current instance of Bash.
+`BASH_EXECUTION_STRING'
+ The command argument to the `-c' invocation option.
+
+`BASH_LINENO'
+ An array variable whose members are the line numbers in source
+ files corresponding to each member of FUNCNAME.
+ `${BASH_LINENO[$i]}' is the line number in the source file where
+ `${FUNCNAME[$i + 1]}' was called. The corresponding source file
+ name is `${BASH_SOURCE[$i + 1]}'. Use `LINENO' to obtain the
+ current line number.
+
+`BASH_REMATCH'
+ An array variable whose members are assigned by the `=~' binary
+ operator to the `[[' conditional command (*note Conditional
+ Constructs::). The element with index 0 is the portion of the
+ string matching the entire regular expression. The element with
+ index N is the portion of the string matching the Nth
+ parenthesized subexpression. This variable is read-only.
+
+`BASH_SOURCE'
+ An array variable whose members are the source filenames
+ corresponding to the elements in the `FUNCNAME' array variable.
+
+`BASH_SUBSHELL'
+ Incremented by one each time a subshell or subshell environment is
+ spawned. The initial value is 0.
`BASH_VERSINFO'
- A readonly array variable (*note Arrays::.) whose members hold
+ A readonly array variable (*note Arrays::) whose members hold
version information for this instance of Bash. The values
assigned to the array members are as follows:
`BASH_VERSINFO[5]'
The value of `MACHTYPE'.
-`COMP_WORDS'
- An array variable consisting of the individual words in the
- current command line. This variable is available only in shell
- functions invoked by the programmable completion facilities (*note
- Programmable Completion::.).
+
+`BASH_VERSION'
+ The version number of the current instance of Bash.
+
+`COLUMNS'
+ Used by the `select' builtin command to determine the terminal
+ width when printing selection lists. Automatically set upon
+ receipt of a `SIGWINCH'.
`COMP_CWORD'
An index into `${COMP_WORDS}' of the word containing the current
cursor position. This variable is available only in shell
functions invoked by the programmable completion facilities (*note
- Programmable Completion::.).
+ Programmable Completion::).
`COMP_LINE'
The current command line. This variable is available only in
shell functions and external commands invoked by the programmable
- completion facilities (*note Programmable Completion::.).
+ completion facilities (*note Programmable Completion::).
`COMP_POINT'
The index of the current cursor position relative to the beginning
end of the current command, the value of this variable is equal to
`${#COMP_LINE}'. This variable is available only in shell
functions and external commands invoked by the programmable
- completion facilities (*note Programmable Completion::.).
+ completion facilities (*note Programmable Completion::).
+
+`COMP_WORDBREAKS'
+ The set of characters that the Readline library treats as word
+ separators when performing word completion. If `COMP_WORDBREAKS'
+ is unset, it loses its special properties, even if it is
+ subsequently reset.
+
+`COMP_WORDS'
+ An array variable consisting of the individual words in the
+ current command line. This variable is available only in shell
+ functions invoked by the programmable completion facilities (*note
+ Programmable Completion::).
`COMPREPLY'
An array variable from which Bash reads the possible completions
generated by a shell function invoked by the programmable
- completion facility (*note Programmable Completion::.).
+ completion facility (*note Programmable Completion::).
`DIRSTACK'
An array variable containing the current contents of the directory
the current directory. If `DIRSTACK' is unset, it loses its
special properties, even if it is subsequently reset.
+`EMACS'
+ If Bash finds this variable in the environment when the shell
+ starts with value `t', it assumes that the shell is running in an
+ emacs shell buffer and disables line editing.
+
`EUID'
The numeric effective user id of the current user. This variable
is readonly.
entries in `FIGNORE' is excluded from the list of matched file
names. A sample value is `.o:~'
+`FUNCNAME'
+ An array variable containing the names of all shell functions
+ currently in the execution call stack. The element with index 0
+ is the name of any currently-executing shell function. The
+ bottom-most element is "main". This variable exists only when a
+ shell function is executing. Assignments to `FUNCNAME' have no
+ effect and return an error status. If `FUNCNAME' is unset, it
+ loses its special properties, even if it is subsequently reset.
+
`GLOBIGNORE'
A colon-separated list of patterns defining the set of filenames to
be ignored by filename expansion. If a filename matched by a
`GROUPS'
An array variable containing the list of groups of which the
current user is a member. Assignments to `GROUPS' have no effect
- and are silently discarded. If `GROUPS' is unset, it loses its
+ and return an error status. If `GROUPS' is unset, it loses its
special properties, even if it is subsequently reset.
`histchars'
Up to three characters which control history expansion, quick
- substitution, and tokenization (*note History Interaction::.).
- The first character is the HISTORY EXPANSION character, that is,
- the character which signifies the start of a history expansion,
+ substitution, and tokenization (*note History Interaction::). The
+ first character is the HISTORY EXPANSION character, that is, the
+ character which signifies the start of a history expansion,
normally `!'. The second character is the character which
signifies `quick substitution' when seen as the first character on
a line, normally `^'. The optional third character is the
command. If `HISTCMD' is unset, it loses its special properties,
even if it is subsequently reset.
-`FUNCNAME'
- The name of any currently-executing shell function. This variable
- exists only when a shell function is executing. Assignments to
- `FUNCNAME' have no effect and are silently discarded. If
- `FUNCNAME' is unset, it loses its special properties, even if it
- is subsequently reset.
-
`HISTCONTROL'
- A value of `ignorespace' means to not enter lines which begin with
- a space or tab into the history list. A value of `ignoredups'
- means to not enter lines which match the last entered line. A
- value of `ignoreboth' combines the two options. Unset, or set to
- any other value than those above, means to save all lines on the
- history list. The second and subsequent lines of a multi-line
- compound command are not tested, and are added to the history
- regardless of the value of `HISTCONTROL'.
+ A colon-separated list of values controlling how commands are
+ saved on the history list. If the list of values includes
+ `ignorespace', lines which begin with a space character are not
+ saved in the history list. A value of `ignoredups' causes lines
+ which match the previous history entry to not be saved. A value
+ of `ignoreboth' is shorthand for `ignorespace' and `ignoredups'.
+ A value of `erasedups' causes all previous lines matching the
+ current line to be removed from the history list before that line
+ is saved. Any value not in the above list is ignored. If
+ `HISTCONTROL' is unset, or does not include a valid value, all
+ lines read by the shell parser are saved on the history list,
+ subject to the value of `HISTIGNORE'. The second and subsequent
+ lines of a multi-line compound command are not tested, and are
+ added to the history regardless of the value of `HISTCONTROL'.
+
+`HISTFILE'
+ The name of the file to which the command history is saved. The
+ default value is `~/.bash_history'.
+
+`HISTFILESIZE'
+ The maximum number of lines contained in the history file. When
+ this variable is assigned a value, the history file is truncated,
+ if necessary, to contain no more than that number of lines. The
+ history file is also truncated to this size after writing it when
+ an interactive shell exits. The default value is 500.
`HISTIGNORE'
A colon-separated list of patterns used to decide which command
separating them with a colon, provides the functionality of
`ignoreboth'.
-`HISTFILE'
- The name of the file to which the command history is saved. The
- default value is `~/.bash_history'.
-
`HISTSIZE'
The maximum number of commands to remember on the history list.
The default value is 500.
-`HISTFILESIZE'
- The maximum number of lines contained in the history file. When
- this variable is assigned a value, the history file is truncated,
- if necessary, to contain no more than that number of lines. The
- history file is also truncated to this size after writing it when
- an interactive shell exits. The default value is 500.
+`HISTTIMEFORMAT'
+ If this variable is set and not null, its value is used as a
+ format string for STRFTIME to print the time stamp associated with
+ each history entry displayed by the `history' builtin. If this
+ variable is set, time stamps are written to the history file so
+ they may be preserved across shell sessions.
`HOSTFILE'
Contains the name of a file in the same format as `/etc/hosts' that
results of filename expansion, and determines the behavior of
range expressions, equivalence classes, and collating sequences
within filename expansion and pattern matching (*note Filename
- Expansion::.).
+ Expansion::).
`LC_CTYPE'
This variable determines the interpretation of characters and the
behavior of character classes within filename expansion and pattern
- matching (*note Filename Expansion::.).
+ matching (*note Filename Expansion::).
`LC_MESSAGES'
This variable determines the locale used to translate double-quoted
- strings preceded by a `$' (*note Locale Translation::.).
+ strings preceded by a `$' (*note Locale Translation::).
`LC_NUMERIC'
This variable determines the locale category used for number
The line number in the script or shell function currently
executing.
+`LINES'
+ Used by the `select' builtin command to determine the column length
+ for printing selection lists. Automatically set upon receipt of a
+ `SIGWINCH'.
+
`MACHTYPE'
A string that fully describes the system type on which Bash is
executing, in the standard GNU CPU-COMPANY-SYSTEM format.
`MAILCHECK'
How often (in seconds) that the shell should check for mail in the
- files specified in the `MAILPATH' or `MAIL' variables.
+ files specified in the `MAILPATH' or `MAIL' variables. The
+ default is 60 seconds. When it is time to check for mail, the
+ shell does so before displaying the primary prompt. If this
+ variable is unset, or set to a value that is not a number greater
+ than or equal to zero, the shell disables mail checking.
`OLDPWD'
The previous working directory as set by the `cd' builtin.
A string describing the operating system Bash is running on.
`PIPESTATUS'
- An array variable (*note Arrays::.) containing a list of exit
+ An array variable (*note Arrays::) containing a list of exit
status values from the processes in the most-recently-executed
foreground pipeline (which may contain only a single command).
+`POSIXLY_CORRECT'
+ If this variable is in the environment when `bash' starts, the
+ shell enters POSIX mode (*note Bash POSIX Mode::) before reading
+ the startup files, as if the `--posix' invocation option had been
+ supplied. If it is set while the shell is running, `bash' enables
+ POSIX mode, as if the command
+ `set -o posix'
+ had been executed.
+
`PPID'
The process ID of the shell's parent process. This variable is
readonly.
`PS4'
The value is the prompt printed before the command line is echoed
- when the `-x' option is set (*note The Set Builtin::.). The first
+ when the `-x' option is set (*note The Set Builtin::). The first
character of `PS4' is replicated multiple times, as necessary, to
indicate multiple levels of indirection. The default is `+ '.
value assigned, and the expanded value becomes the value assigned
plus the number of seconds since the assignment.
+`SHELL'
+ The full pathname to the shell is kept in this environment
+ variable. If it is not set when the shell starts, Bash assigns to
+ it the full pathname of the current user's login shell.
+
`SHELLOPTS'
A colon-separated list of enabled shell options. Each word in the
list is a valid argument for the `-o' option to the `set' builtin
- command (*note The Set Builtin::.). The options appearing in
+ command (*note The Set Builtin::). The options appearing in
`SHELLOPTS' are those reported as `on' by `set -o'. If this
variable is in the environment when Bash starts up, each shell
option in the list will be enabled before reading any startup
trailing newline is added when the format string is displayed.
`TMOUT'
- If set to a value greater than zero, the value is interpreted as
- the number of seconds to wait for input after issuing the primary
- prompt when the shell is interactive. Bash terminates after that
- number of seconds if input does not arrive.
+ If set to a value greater than zero, `TMOUT' is treated as the
+ default timeout for the `read' builtin (*note Bash Builtins::).
+ The `select' command (*note Conditional Constructs::) terminates
+ if input does not arrive after `TMOUT' seconds when input is coming
+ from a terminal.
+
+ In an interative shell, the value is interpreted as the number of
+ seconds to wait for input after issuing the primary prompt when
+ the shell is interactive. Bash terminates after that number of
+ seconds if input does not arrive.
`UID'
The numeric real user id of the current user. This variable is
readonly.
+
\1f
File: bashref.info, Node: Bash Features, Next: Job Control, Prev: Shell Variables, Up: Top
-Bash Features
-*************
+6 Bash Features
+***************
- This section describes features unique to Bash.
+This section describes features unique to Bash.
* Menu:
\1f
File: bashref.info, Node: Invoking Bash, Next: Bash Startup Files, Up: Bash Features
-Invoking Bash
-=============
+6.1 Invoking Bash
+=================
- bash [long-opt] [-ir] [-abefhkmnptuvxdBCDHP] [-o OPTION] [ARGUMENT ...]
- bash [long-opt] [-abefhkmnptuvxdBCDHP] [-o OPTION] -c STRING [ARGUMENT ...]
- bash [long-opt] -s [-abefhkmnptuvxdBCDHP] [-o OPTION] [ARGUMENT ...]
+ bash [long-opt] [-ir] [-abefhkmnptuvxdBCDHP] [-o OPTION] [-O SHOPT_OPTION] [ARGUMENT ...]
+ bash [long-opt] [-abefhkmnptuvxdBCDHP] [-o OPTION] [-O SHOPT_OPTION] -c STRING [ARGUMENT ...]
+ bash [long-opt] -s [-abefhkmnptuvxdBCDHP] [-o OPTION] [-O SHOPT_OPTION] [ARGUMENT ...]
In addition to the single-character shell command-line options
-(*note The Set Builtin::.), there are several multi-character options
+(*note The Set Builtin::), there are several multi-character options
that you can use. These options must appear on the command line before
-the single-character options in order for them to be recognized.
+the single-character options to be recognized.
+
+`--debugger'
+ Arrange for the debugger profile to be executed before the shell
+ starts. Turns on extended debugging mode (see *Note Bash
+ Builtins:: for a description of the `extdebug' option to the
+ `shopt' builtin) and shell function tracing (see *Note The Set
+ Builtin:: for a description of the `-o functrace' option).
`--dump-po-strings'
A list of all double-quoted strings preceded by `$' is printed on
`--help'
Display a usage message on standard output and exit sucessfully.
+`--init-file FILENAME'
+`--rcfile FILENAME'
+ Execute commands from FILENAME (instead of `~/.bashrc') in an
+ interactive shell.
+
`--login'
- Make this shell act as if it were directly invoked by login. This
- is equivalent to `exec -l bash' but can be issued from another
- shell, such as `csh'. `exec bash --login' will replace the
- current shell with a Bash login shell. *Note Bash Startup
- Files::, for a description of the special behavior of a login
- shell.
+ Equivalent to `-l'.
`--noediting'
- Do not use the GNU Readline library (*note Command Line Editing::.)
+ Do not use the GNU Readline library (*note Command Line Editing::)
to read command lines when the shell is interactive.
`--noprofile'
standard. *Note Bash POSIX Mode::, for a description of the Bash
POSIX mode.
-`--rcfile FILENAME'
- Execute commands from FILENAME (instead of `~/.bashrc') in an
- interactive shell.
-
`--restricted'
- Make the shell a restricted shell (*note The Restricted Shell::.).
+ Make the shell a restricted shell (*note The Restricted Shell::).
`--verbose'
Equivalent to `-v'. Print shell input lines as they're read.
Show version information for this instance of Bash on the standard
output and exit successfully.
+
There are several single-character options that may be supplied at
invocation which are not available with the `set' builtin.
Force the shell to run interactively. Interactive shells are
described in *Note Interactive Shells::.
+`-l'
+ Make this shell act as if it had been directly invoked by login.
+ When the shell is interactive, this is equivalent to starting a
+ login shell with `exec -l bash'. When the shell is not
+ interactive, the login shell startup files will be executed.
+ `exec bash -l' or `exec bash --login' will replace the current
+ shell with a Bash login shell. *Note Bash Startup Files::, for a
+ description of the special behavior of a login shell.
+
`-r'
- Make the shell a restricted shell (*note The Restricted Shell::.).
+ Make the shell a restricted shell (*note The Restricted Shell::).
`-s'
If this option is present, or if no arguments remain after option
A list of all double-quoted strings preceded by `$' is printed on
the standard ouput. These are the strings that are subject to
language translation when the current locale is not `C' or `POSIX'
- (*note Locale Translation::.). This implies the `-n' option; no
+ (*note Locale Translation::). This implies the `-n' option; no
commands will be executed.
+`[-+]O [SHOPT_OPTION]'
+ SHOPT_OPTION is one of the shell options accepted by the `shopt'
+ builtin (*note Shell Builtin Commands::). If SHOPT_OPTION is
+ present, `-O' sets the value of that option; `+O' unsets it. If
+ SHOPT_OPTION is not supplied, the names and values of the shell
+ options accepted by `shopt' are printed on the standard output.
+ If the invocation option is `+O', the output is displayed in a
+ format that may be reused as input.
+
`--'
A `--' signals the end of options and disables further option
processing. Any arguments after the `--' are treated as filenames
and arguments.
- An *interactive* shell is one started without non-option arguments,
+
+ A _login_ shell is one whose first character of argument zero is
+`-', or one invoked with the `--login' option.
+
+ An _interactive_ shell is one started without non-option arguments,
unless `-s' is specified, without specifying the `-c' option, and whose
input and output are both connected to terminals (as determined by
`isatty(3)'), or one started with the `-i' option. *Note Interactive
-Shells:: for more information.
+Shells::, for more information.
If arguments remain after option processing, and neither the `-c'
nor the `-s' option has been supplied, the first argument is assumed to
-be the name of a file containing shell commands (*note Shell
-Scripts::.). When Bash is invoked in this fashion, `$0' is set to the
-name of the file, and the positional parameters are set to the
-remaining arguments. Bash reads and executes commands from this file,
-then exits. Bash's exit status is the exit status of the last command
-executed in the script. If no commands are executed, the exit status
-is 0.
+be the name of a file containing shell commands (*note Shell Scripts::).
+When Bash is invoked in this fashion, `$0' is set to the name of the
+file, and the positional parameters are set to the remaining arguments.
+Bash reads and executes commands from this file, then exits. Bash's
+exit status is the exit status of the last command executed in the
+script. If no commands are executed, the exit status is 0.
\1f
File: bashref.info, Node: Bash Startup Files, Next: Interactive Shells, Prev: Invoking Bash, Up: Bash Features
-Bash Startup Files
-==================
+6.2 Bash Startup Files
+======================
- This section describs how Bash executes its startup files. If any
-of the files exist but cannot be read, Bash reports an error. Tildes
-are expanded in file names as described above under Tilde Expansion
-(*note Tilde Expansion::.).
+This section describs how Bash executes its startup files. If any of
+the files exist but cannot be read, Bash reports an error. Tildes are
+expanded in file names as described above under Tilde Expansion (*note
+Tilde Expansion::).
Interactive shells are described in *Note Interactive Shells::.
Invoked as an interactive login shell, or with `--login'
........................................................
- When Bash is invoked as an interactive login shell, or as a
+When Bash is invoked as an interactive login shell, or as a
non-interactive shell with the `--login' option, it first reads and
executes commands from the file `/etc/profile', if that file exists.
After reading that file, it looks for `~/.bash_profile',
Invoked as an interactive non-login shell
.........................................
- When an interactive shell that is not a login shell is started, Bash
+When an interactive shell that is not a login shell is started, Bash
reads and executes commands from `~/.bashrc', if that file exists.
This may be inhibited by using the `--norc' option. The `--rcfile
FILE' option will force Bash to read and execute commands from FILE
So, typically, your `~/.bash_profile' contains the line
`if [ -f ~/.bashrc ]; then . ~/.bashrc; fi'
-
-after (or before) any login-specific initializations.
+ after (or before) any login-specific initializations.
Invoked non-interactively
.........................
- When Bash is started non-interactively, to run a shell script, for
+When Bash is started non-interactively, to run a shell script, for
example, it looks for the variable `BASH_ENV' in the environment,
expands its value if it appears there, and uses the expanded value as
the name of a file to read and execute. Bash behaves as if the
following command were executed:
`if [ -n "$BASH_ENV" ]; then . "$BASH_ENV"; fi'
+ but the value of the `PATH' variable is not used to search for the
+file name.
-but the value of the `PATH' variable is not used to search for the file
-name.
+ As noted above, if a non-interactive shell is invoked with the
+`--login' option, Bash attempts to read and execute commands from the
+login shell startup files.
Invoked with name `sh'
......................
- If Bash is invoked with the name `sh', it tries to mimic the startup
+If Bash is invoked with the name `sh', it tries to mimic the startup
behavior of historical versions of `sh' as closely as possible, while
conforming to the POSIX standard as well.
Invoked in POSIX mode
.....................
- When Bash is started in POSIX mode, as with the `--posix' command
-line option, it follows the POSIX standard for startup files. In this
-mode, interactive shells expand the `ENV' variable and commands are
-read and executed from the file whose name is the expanded value. No
-other startup files are read.
+When Bash is started in POSIX mode, as with the `--posix' command line
+option, it follows the POSIX standard for startup files. In this mode,
+interactive shells expand the `ENV' variable and commands are read and
+executed from the file whose name is the expanded value. No other
+startup files are read.
Invoked by remote shell daemon
..............................
- Bash attempts to determine when it is being run by the remote shell
+Bash attempts to determine when it is being run by the remote shell
daemon, usually `rshd'. If Bash determines it is being run by rshd, it
reads and executes commands from `~/.bashrc', if that file exists and
is readable. It will not do this if invoked as `sh'. The `--norc'
Invoked with unequal effective and real UID/GIDs
................................................
- If Bash is started with the effective user (group) id not equal to
-the real user (group) id, and the `-p' option is not supplied, no
-startup files are read, shell functions are not inherited from the
-environment, the `SHELLOPTS' variable, if it appears in the
-environment, is ignored, and the effective user id is set to the real
-user id. If the `-p' option is supplied at invocation, the startup
-behavior is the same, but the effective user id is not reset.
+If Bash is started with the effective user (group) id not equal to the
+real user (group) id, and the `-p' option is not supplied, no startup
+files are read, shell functions are not inherited from the environment,
+the `SHELLOPTS' variable, if it appears in the environment, is ignored,
+and the effective user id is set to the real user id. If the `-p'
+option is supplied at invocation, the startup behavior is the same, but
+the effective user id is not reset.
\1f
File: bashref.info, Node: Interactive Shells, Next: Bash Conditional Expressions, Prev: Bash Startup Files, Up: Bash Features
-Interactive Shells
-==================
+6.3 Interactive Shells
+======================
* Menu:
\1f
File: bashref.info, Node: What is an Interactive Shell?, Next: Is this Shell Interactive?, Up: Interactive Shells
-What is an Interactive Shell?
------------------------------
+6.3.1 What is an Interactive Shell?
+-----------------------------------
- An interactive shell is one started without non-option arguments,
+An interactive shell is one started without non-option arguments,
unless `-s' is specified, without specifiying the `-c' option, and
-whose input and output are both connected to terminals (as determined
-by `isatty(3)'), or one started with the `-i' option.
+whose input and error output are both connected to terminals (as
+determined by `isatty(3)'), or one started with the `-i' option.
An interactive shell generally reads from and writes to a user's
terminal.
\1f
File: bashref.info, Node: Is this Shell Interactive?, Next: Interactive Shell Behavior, Prev: What is an Interactive Shell?, Up: Interactive Shells
-Is this Shell Interactive?
---------------------------
+6.3.2 Is this Shell Interactive?
+--------------------------------
- To determine within a startup script whether or not Bash is running
+To determine within a startup script whether or not Bash is running
interactively, test the value of the `-' special parameter. It
contains `i' when the shell is interactive. For example:
*) echo This shell is not interactive ;;
esac
- Alternatively, startup scripts may examine the variable `$PS1'; it
-is unset in non-interactive shells, and set in interactive shells.
-Thus:
+ Alternatively, startup scripts may examine the variable `PS1'; it is
+unset in non-interactive shells, and set in interactive shells. Thus:
if [ -z "$PS1" ]; then
echo This shell is not interactive
\1f
File: bashref.info, Node: Interactive Shell Behavior, Prev: Is this Shell Interactive?, Up: Interactive Shells
-Interactive Shell Behavior
---------------------------
+6.3.3 Interactive Shell Behavior
+--------------------------------
- When the shell is running interactively, it changes its behavior in
+When the shell is running interactively, it changes its behavior in
several ways.
1. Startup files are read and executed as described in *Note Bash
Startup Files::.
- 2. Job Control (*note Job Control::.) is enabled by default. When job
+ 2. Job Control (*note Job Control::) is enabled by default. When job
control is in effect, Bash ignores the keyboard-generated job
control signals `SIGTTIN', `SIGTTOU', and `SIGTSTP'.
- 3. Bash expands and displays `$PS1' before reading the first line of
- a command, and expands and displays `$PS2' before reading the
- second and subsequent lines of a multi-line command.
+ 3. Bash expands and displays `PS1' before reading the first line of a
+ command, and expands and displays `PS2' before reading the second
+ and subsequent lines of a multi-line command.
4. Bash executes the value of the `PROMPT_COMMAND' variable as a
command before printing the primary prompt, `$PS1' (*note Bash
- Variables::.).
+ Variables::).
- 5. Readline (*note Command Line Editing::.) is used to read commands
+ 5. Readline (*note Command Line Editing::) is used to read commands
from the user's terminal.
6. Bash inspects the value of the `ignoreeof' option to `set -o'
instead of exiting immediately when it receives an `EOF' on its
- standard input when reading a command (*note The Set Builtin::.).
+ standard input when reading a command (*note The Set Builtin::).
- 7. Command history (*note Bash History Facilities::.) and history
- expansion (*note History Interaction::.) are enabled by default.
+ 7. Command history (*note Bash History Facilities::) and history
+ expansion (*note History Interaction::) are enabled by default.
Bash will save the command history to the file named by `$HISTFILE'
when an interactive shell exits.
- 8. Alias expansion (*note Aliases::.) is performed by default.
+ 8. Alias expansion (*note Aliases::) is performed by default.
9. In the absence of any traps, Bash ignores `SIGTERM' (*note
- Signals::.).
+ Signals::).
10. In the absence of any traps, `SIGINT' is caught and handled
- ((*note Signals::.). `SIGINT' will interrupt some shell builtins.
+ ((*note Signals::). `SIGINT' will interrupt some shell builtins.
11. An interactive login shell sends a `SIGHUP' to all jobs on exit if
- the `hupoxexit' shell option has been enabled (*note Signals::.).
+ the `hupoxexit' shell option has been enabled (*note Signals::).
12. The `-n' invocation option is ignored, and `set -n' has no effect
- (*note The Set Builtin::.).
+ (*note The Set Builtin::).
13. Bash will check for mail periodically, depending on the values of
the `MAIL', `MAILPATH', and `MAILCHECK' shell variables (*note
- Bash Variables::.).
+ Bash Variables::).
14. Expansion errors due to references to unbound shell variables after
`set -u' has been enabled will not cause the shell to exit (*note
- The Set Builtin::.).
+ The Set Builtin::).
15. The shell will not exit on expansion errors caused by VAR being
unset or null in `${VAR:?WORD}' expansions (*note Shell Parameter
- Expansion::.).
+ Expansion::).
16. Redirection errors encountered by shell builtins will not cause the
shell to exit.
17. When running in POSIX mode, a special builtin returning an error
- status will not cause the shell to exit (*note Bash POSIX Mode::.).
+ status will not cause the shell to exit (*note Bash POSIX Mode::).
18. A failed `exec' will not cause the shell to exit (*note Bourne
- Shell Builtins::.).
+ Shell Builtins::).
19. Parser syntax errors will not cause the shell to exit.
21. The shell will check the value of the `TMOUT' variable and exit if
a command is not read within the specified number of seconds after
- printing `$PS1' (*note Bash Variables::.).
+ printing `$PS1' (*note Bash Variables::).
\1f
File: bashref.info, Node: Bash Conditional Expressions, Next: Shell Arithmetic, Prev: Interactive Shells, Up: Bash Features
-Bash Conditional Expressions
-============================
+6.4 Bash Conditional Expressions
+================================
- Conditional expressions are used by the `[[' compound command and
-the `test' and `[' builtin commands.
+Conditional expressions are used by the `[[' compound command and the
+`test' and `[' builtin commands.
Expressions may be unary or binary. Unary expressions are often
used to examine the status of a file. There are string operators and
True if FILE exists and has been modified since it was last read.
`FILE1 -nt FILE2'
- True if FILE1 is newer (according to modification date) than FILE2.
+ True if FILE1 is newer (according to modification date) than
+ FILE2, or if FILE1 exists and FILE2 does not.
`FILE1 -ot FILE2'
- True if FILE1 is older than FILE2.
+ True if FILE1 is older than FILE2, or if FILE2 exists and FILE1
+ does not.
`FILE1 -ef FILE2'
- True if FILE1 and FILE2 have the same device and inode numbers.
+ True if FILE1 and FILE2 refer to the same device and inode numbers.
`-o OPTNAME'
True if shell option OPTNAME is enabled. The list of options
appears in the description of the `-o' option to the `set' builtin
- (*note The Set Builtin::.).
+ (*note The Set Builtin::).
`-z STRING'
True if the length of STRING is zero.
True if the length of STRING is non-zero.
`STRING1 == STRING2'
- True if the strings are equal. `=' may be used in place of `=='.
+ True if the strings are equal. `=' may be used in place of `=='
+ for strict POSIX compliance.
`STRING1 != STRING2'
True if the strings are not equal.
greater than or equal to ARG2, respectively. ARG1 and ARG2 may be
positive or negative integers.
+
\1f
File: bashref.info, Node: Shell Arithmetic, Next: Aliases, Prev: Bash Conditional Expressions, Up: Bash Features
-Shell Arithmetic
-================
+6.5 Shell Arithmetic
+====================
- The shell allows arithmetic expressions to be evaluated, as one of
-the shell expansions or by the `let' builtin.
+The shell allows arithmetic expressions to be evaluated, as one of the
+shell expansions or by the `let' and the `-i' option to the `declare'
+builtins.
- Evaluation is done in long integers with no check for overflow,
-though division by 0 is trapped and flagged as an error. The operators
-and their precedence and associativity are the same as in the C
-language. The following list of operators is grouped into levels of
-equal-precedence operators. The levels are listed in order of
-decreasing precedence.
+ Evaluation is done in fixed-width integers with no check for
+overflow, though division by 0 is trapped and flagged as an error. The
+operators and their precedence, associativity, and values are the same
+as in the C language. The following list of operators is grouped into
+levels of equal-precedence operators. The levels are listed in order
+of decreasing precedence.
`ID++ ID--'
variable post-increment and post-decrement
logical OR
`expr ? expr : expr'
- conditional evaluation
+ conditional operator
`= *= /= %= += -= <<= >>= &= ^= |='
assignment
Shell variables are allowed as operands; parameter expansion is
performed before the expression is evaluated. Within an expression,
shell variables may also be referenced by name without using the
-parameter expansion syntax. The value of a variable is evaluated as an
-arithmetic expression when it is referenced. A shell variable need not
-have its integer attribute turned on to be used in an expression.
+parameter expansion syntax. A shell variable that is null or unset
+evaluates to 0 when referenced by name without using the parameter
+expansion syntax. The value of a variable is evaluated as an
+arithmetic expression when it is referenced, or when a variable which
+has been given the INTEGER attribute using `declare -i' is assigned a
+value. A null value evaluates to 0. A shell variable need not have
+its integer attribute turned on to be used in an expression.
Constants with a leading 0 are interpreted as octal numbers. A
leading `0x' or `0X' denotes hexadecimal. Otherwise, numbers take the
form [BASE`#']N, where BASE is a decimal number between 2 and 64
representing the arithmetic base, and N is a number in that base. If
BASE`#' is omitted, then base 10 is used. The digits greater than 9
-are represented by the lowercase letters, the uppercase letters, `_',
-and `@', in that order. If BASE is less than or equal to 36, lowercase
+are represented by the lowercase letters, the uppercase letters, `@',
+and `_', in that order. If BASE is less than or equal to 36, lowercase
and uppercase letters may be used interchangably to represent numbers
between 10 and 35.
\1f
File: bashref.info, Node: Aliases, Next: Arrays, Prev: Shell Arithmetic, Up: Bash Features
-Aliases
-=======
+6.6 Aliases
+===========
- ALIASES allow a string to be substituted for a word when it is used
-as the first word of a simple command. The shell maintains a list of
+ALIASES allow a string to be substituted for a word when it is used as
+the first word of a simple command. The shell maintains a list of
aliases that may be set and unset with the `alias' and `unalias'
builtin commands.
The first word of each simple command, if unquoted, is checked to see
if it has an alias. If so, that word is replaced by the text of the
-alias. The alias name and the replacement text may contain any valid
-shell input, including shell metacharacters, with the exception that
-the alias name may not contain `='. The first word of the replacement
-text is tested for aliases, but a word that is identical to an alias
-being expanded is not expanded a second time. This means that one may
-alias `ls' to `"ls -F"', for instance, and Bash does not try to
-recursively expand the replacement text. If the last character of the
-alias value is a space or tab character, then the next command word
-following the alias is also checked for alias expansion.
+alias. The characters `/', `$', ``', `=' and any of the shell
+metacharacters or quoting characters listed above may not appear in an
+alias name. The replacement text may contain any valid shell input,
+including shell metacharacters. The first word of the replacement text
+is tested for aliases, but a word that is identical to an alias being
+expanded is not expanded a second time. This means that one may alias
+`ls' to `"ls -F"', for instance, and Bash does not try to recursively
+expand the replacement text. If the last character of the alias value
+is a space or tab character, then the next command word following the
+alias is also checked for alias expansion.
Aliases are created and listed with the `alias' command, and removed
with the `unalias' command.
There is no mechanism for using arguments in the replacement text,
as in `csh'. If arguments are needed, a shell function should be used
-(*note Shell Functions::.).
+(*note Shell Functions::).
Aliases are not expanded when the shell is not interactive, unless
the `expand_aliases' shell option is set using `shopt' (*note Bash
-Builtins::.).
+Builtins::).
The rules concerning the definition and use of aliases are somewhat
confusing. Bash always reads at least one complete line of input
\1f
File: bashref.info, Node: Arrays, Next: The Directory Stack, Prev: Aliases, Up: Bash Features
-Arrays
-======
+6.7 Arrays
+==========
- Bash provides one-dimensional array variables. Any variable may be
+Bash provides one-dimensional array variables. Any variable may be
used as an array; the `declare' builtin will explicitly declare an
array. There is no maximum limit on the size of an array, nor any
requirement that members be indexed or assigned contiguously. Arrays
to a number greater than or equal to zero. To explicitly declare an
array, use
declare -a NAME
-
-The syntax
+ The syntax
declare -a NAME[SUBSCRIPT]
-
-is also accepted; the SUBSCRIPT is ignored. Attributes may be
+ is also accepted; the SUBSCRIPT is ignored. Attributes may be
specified for an array variable using the `declare' and `readonly'
builtins. Each attribute applies to all members of an array.
Arrays are assigned to using compound assignments of the form
name=(value1 ... valueN)
-
-where each VALUE is of the form `[[SUBSCRIPT]=]'STRING. If the
+ where each VALUE is of the form `[[SUBSCRIPT]=]'STRING. If the
optional subscript is supplied, that index is assigned to; otherwise
the index of the element assigned is the last index assigned to by the
statement plus one. Indexing starts at zero. This syntax is also
\1f
File: bashref.info, Node: The Directory Stack, Next: Printing a Prompt, Prev: Arrays, Up: Bash Features
-The Directory Stack
-===================
+6.8 The Directory Stack
+=======================
* Menu:
\1f
File: bashref.info, Node: Directory Stack Builtins, Up: The Directory Stack
-Directory Stack Builtins
-------------------------
+6.8.1 Directory Stack Builtins
+------------------------------
`dirs'
dirs [+N | -N] [-clpv]
Makes the current working directory be the top of the stack,
and then executes the equivalent of ``cd' DIR'. `cd's to DIR.
+
\1f
File: bashref.info, Node: Printing a Prompt, Next: The Restricted Shell, Prev: The Directory Stack, Up: Bash Features
-Controlling the Prompt
-======================
+6.9 Controlling the Prompt
+==========================
- The value of the variable `PROMPT_COMMAND' is examined just before
-Bash prints each primary prompt. If `PROMPT_COMMAND' is set and has a
+The value of the variable `PROMPT_COMMAND' is examined just before Bash
+prints each primary prompt. If `PROMPT_COMMAND' is set and has a
non-null value, then the value is executed just as if it had been typed
on the command line.
`\d'
The date, in "Weekday Month Date" format (e.g., "Tue May 26").
+`\D{FORMAT}'
+ The FORMAT is passed to `strftime'(3) and the result is inserted
+ into the prompt string; an empty FORMAT results in a
+ locale-specific time representation. The braces are required.
+
`\e'
An escape character.
`\@'
The time, in 12-hour am/pm format.
+`\A'
+ The time, in 24-hour HH:MM format.
+
`\u'
The username of the current user.
The release of Bash, version + patchlevel (e.g., 2.00.0)
`\w'
- The current working directory.
+ The current working directory, with `$HOME' abbreviated with a
+ tilde.
`\W'
- The basename of `$PWD'.
+ The basename of `$PWD', with `$HOME' abbreviated with a tilde.
`\!'
The history number of this command.
The command number and the history number are usually different: the
history number of a command is its position in the history list, which
may include commands restored from the history file (*note Bash History
-Facilities::.), while the command number is the position in the
-sequence of commands executed during the current shell session.
+Facilities::), while the command number is the position in the sequence
+of commands executed during the current shell session.
After the string is decoded, it is expanded via parameter expansion,
command substitution, arithmetic expansion, and quote removal, subject
-to the value of the `promptvars' shell option (*note Bash Builtins::.).
+to the value of the `promptvars' shell option (*note Bash Builtins::).
\1f
File: bashref.info, Node: The Restricted Shell, Next: Bash POSIX Mode, Prev: Printing a Prompt, Up: Bash Features
-The Restricted Shell
-====================
+6.10 The Restricted Shell
+=========================
- If Bash is started with the name `rbash', or the `--restricted'
+If Bash is started with the name `rbash', or the `--restricted' or `-r'
option is supplied at invocation, the shell becomes restricted. A
restricted shell is used to set up an environment more controlled than
the standard shell. A restricted shell behaves identically to `bash'
-with the exception that the following are disallowed:
+with the exception that the following are disallowed or not performed:
+
* Changing directories with the `cd' builtin.
* Setting or unsetting the values of the `SHELL', `PATH', `ENV', or
* Adding or deleting builtin commands with the `-f' and `-d' options
to the `enable' builtin.
+ * Using the `enable' builtin command to enable disabled shell
+ builtins.
+
* Specifying the `-p' option to the `command' builtin.
* Turning off restricted mode with `set +r' or `set +o restricted'.
+ These restrictions are enforced after any startup files are read.
+
+ When a command that is found to be a shell script is executed (*note
+Shell Scripts::), `rbash' turns off any restrictions in the shell
+spawned to execute the script.
+
\1f
File: bashref.info, Node: Bash POSIX Mode, Prev: The Restricted Shell, Up: Bash Features
-Bash POSIX Mode
-===============
+6.11 Bash POSIX Mode
+====================
+
+Starting Bash with the `--posix' command-line option or executing `set
+-o posix' while Bash is running will cause Bash to conform more closely
+to the POSIX 1003.2 standard by changing the behavior to match that
+specified by POSIX in areas where the Bash default differs.
- Starting Bash with the `--posix' command-line option or executing
-`set -o posix' while Bash is running will cause Bash to conform more
-closely to the POSIX 1003.2 standard by changing the behavior to match
-that specified by POSIX in areas where the Bash default differs.
+ When invoked as `sh', Bash enters POSIX mode after reading the
+startup files.
The following list is what's changed when `POSIX mode' is in effect:
re-search `$PATH' to find the new location. This is also
available with `shopt -s checkhash'.
- 2. The `>&' redirection does not redirect stdout and stderr.
+ 2. The message printed by the job control code and builtins when a job
+ exits with a non-zero status is `Done(status)'.
3. The message printed by the job control code and builtins when a job
- exits with a non-zero status is `Done(status)'.
+ is stopped is `Stopped(SIGNAME)', where SIGNAME is, for example,
+ `SIGTSTP'.
4. Reserved words may not be aliased.
performed on the values of `PS1' and `PS2' regardless of the
setting of the `promptvars' option.
- 6. Interactive comments are enabled by default. (Bash has them on by
- default anyway.)
-
- 7. The POSIX 1003.2 startup files are executed (`$ENV') rather than
+ 6. The POSIX 1003.2 startup files are executed (`$ENV') rather than
the normal Bash files.
- 8. Tilde expansion is only performed on assignments preceding a
+ 7. Tilde expansion is only performed on assignments preceding a
command name, rather than on all assignment statements on the line.
- 9. The default history file is `~/.sh_history' (this is the default
+ 8. The default history file is `~/.sh_history' (this is the default
value of `$HISTFILE').
- 10. The output of `kill -l' prints all the signal names on a single
- line, separated by spaces.
+ 9. The output of `kill -l' prints all the signal names on a single
+ line, separated by spaces, without the `SIG' prefix.
+
+ 10. The `kill' builtin does not accept signal names with a `SIG'
+ prefix.
11. Non-interactive shells exit if FILENAME in `.' FILENAME is not
found.
`$CDPATH', the value it assigns to the `PWD' variable does not
contain any symbolic links, as if `cd -P' had been executed.
- 19. If `$CDPATH' is set, the `cd' builtin will not implicitly append
+ 19. If `CDPATH' is set, the `cd' builtin will not implicitly append
the current directory to it. This means that `cd' will fail if no
valid directory name can be constructed from any of the entries in
`$CDPATH', even if the a directory with the same name as the name
23. Assignment statements preceding POSIX 1003.2 special builtins
persist in the shell environment after the builtin completes.
- 24. The `export' and `readonly' builtin commands display their output
+ 24. Assignment statements preceding shell function calls persist in the
+ shell environment after the function returns, as if a POSIX
+ special builtin command had been executed.
+
+ 25. The `export' and `readonly' builtin commands display their output
in the format required by POSIX 1003.2.
+ 26. The `trap' builtin displays signal names without the leading `SIG'.
+
+ 27. The `trap' builtin doesn't check the first argument for a possible
+ signal specification and revert the signal handling to the original
+ disposition if it is. If users want to reset the handler for a
+ given signal to the original disposition, they should use `-' as
+ the first argument.
+
+ 28. The `.' and `source' builtins do not search the current directory
+ for the filename argument if it is not found by searching `PATH'.
+
+ 29. Subshells spawned to execute command substitutions inherit the
+ value of the `-e' option from the parent shell. When not in POSIX
+ mode, Bash clears the `-e' option in such subshells.
+
+ 30. Alias expansion is always enabled, even in non-interactive shells.
+
+ 31. When the `alias' builtin displays alias definitions, it does not
+ display them with a leading `alias ' unless the `-p' option is
+ supplied.
+
+ 32. When the `set' builtin is invoked without options, it does not
+ display shell function names and definitions.
+
+ 33. When the `set' builtin is invoked without options, it displays
+ variable values without quotes, unless they contain shell
+ metacharacters, even if the result contains nonprinting characters.
+
+ 34. When the `cd' builtin is invoked in LOGICAL mode, and the pathname
+ constructed from `$PWD' and the directory name supplied as an
+ argument does not refer to an existing directory, `cd' will fail
+ instead of falling back to PHYSICAL mode.
There is other POSIX 1003.2 behavior that Bash does not implement.
Specifically:
1. Assignment statements affect the execution environment of all
builtins, not just special ones.
+ 2. When a subshell is created to execute a shell script with execute
+ permission, but without a leading `#!', Bash sets `$0' to the full
+ pathname of the script as found by searching `$PATH', rather than
+ the command as typed by the user.
+
+ 3. When using `.' to source a shell script found in `$PATH', bash
+ checks execute permission bits rather than read permission bits,
+ just as if it were searching for a command.
+
+
\1f
File: bashref.info, Node: Job Control, Next: Using History Interactively, Prev: Bash Features, Up: Top
-Job Control
-***********
+7 Job Control
+*************
- This chapter discusses what job control is, how it works, and how
-Bash allows you to access its facilities.
+This chapter discusses what job control is, how it works, and how Bash
+allows you to access its facilities.
* Menu:
\1f
File: bashref.info, Node: Job Control Basics, Next: Job Control Builtins, Up: Job Control
-Job Control Basics
-==================
+7.1 Job Control Basics
+======================
- Job control refers to the ability to selectively stop (suspend) the
+Job control refers to the ability to selectively stop (suspend) the
execution of processes and continue (resume) their execution at a later
point. A user typically employs this facility via an interactive
interface supplied jointly by the system's terminal driver and Bash.
currently executing jobs, which may be listed with the `jobs' command.
When Bash starts a job asynchronously, it prints a line that looks like:
[1] 25647
-
-indicating that this job is job number 1 and that the process ID of the
-last process in the pipeline associated with this job is 25647. All of
-the processes in a single pipeline are members of the same job. Bash
-uses the JOB abstraction as the basis for job control.
+ indicating that this job is job number 1 and that the process ID of
+the last process in the pipeline associated with this job is 25647.
+All of the processes in a single pipeline are members of the same job.
+Bash uses the JOB abstraction as the basis for job control.
To facilitate the implementation of the user interface to job
control, the operating system maintains the notion of a current terminal
The shell learns immediately whenever a job changes state.
Normally, Bash waits until it is about to print a prompt before
reporting changes in a job's status so as to not interrupt any other
-output. If the the `-b' option to the `set' builtin is enabled, Bash
-reports such changes immediately (*note The Set Builtin::.).
+output. If the `-b' option to the `set' builtin is enabled, Bash
+reports such changes immediately (*note The Set Builtin::). Any trap
+on `SIGCHLD' is executed for each child process that exits.
- If an attempt to exit Bash is while jobs are stopped, the shell
+ If an attempt to exit Bash is made while jobs are stopped, the shell
prints a message warning that there are stopped jobs. The `jobs'
command may then be used to inspect their status. If a second attempt
to exit is made without an intervening command, Bash does not print
\1f
File: bashref.info, Node: Job Control Builtins, Next: Job Control Variables, Prev: Job Control Basics, Up: Job Control
-Job Control Builtins
-====================
+7.2 Job Control Builtins
+========================
`bg'
bg [JOBSPEC]
kill -l [EXIT_STATUS]
Send a signal specified by SIGSPEC or SIGNUM to the process named
by job specification JOBSPEC or process ID PID. SIGSPEC is either
- a signal name such as `SIGINT' (with or without the `SIG' prefix)
- or a signal number; SIGNUM is a signal number. If SIGSPEC and
- SIGNUM are not present, `SIGTERM' is used. The `-l' option lists
- the signal names. If any arguments are supplied when `-l' is
- given, the names of the signals corresponding to the arguments are
- listed, and the return status is zero. EXIT_STATUS is a number
- specifying a signal number or the exit status of a process
- terminated by a signal. The return status is zero if at least one
- signal was successfully sent, or non-zero if an error occurs or an
- invalid option is encountered.
+ a case-insensitive signal name such as `SIGINT' (with or without
+ the `SIG' prefix) or a signal number; SIGNUM is a signal number.
+ If SIGSPEC and SIGNUM are not present, `SIGTERM' is used. The
+ `-l' option lists the signal names. If any arguments are supplied
+ when `-l' is given, the names of the signals corresponding to the
+ arguments are listed, and the return status is zero. EXIT_STATUS
+ is a number specifying a signal number or the exit status of a
+ process terminated by a signal. The return status is zero if at
+ least one signal was successfully sent, or non-zero if an error
+ occurs or an invalid option is encountered.
`wait'
wait [JOBSPEC or PID]
signal. The `-f' option means to suspend even if the shell is a
login shell.
+
When job control is not active, the `kill' and `wait' builtins do
not accept JOBSPEC arguments. They must be supplied process IDs.
\1f
File: bashref.info, Node: Job Control Variables, Prev: Job Control Builtins, Up: Job Control
-Job Control Variables
-=====================
+7.3 Job Control Variables
+=========================
`auto_resume'
This variable controls how the shell interacts with the user and
`substring', the string supplied needs to match a substring of the
name of a stopped job. The `substring' value provides
functionality analogous to the `%?' job ID (*note Job Control
- Basics::.). If set to any other value, the supplied string must
- be a prefix of a stopped job's name; this provides functionality
+ Basics::). If set to any other value, the supplied string must be
+ a prefix of a stopped job's name; this provides functionality
analogous to the `%' job ID.
+
\1f
File: bashref.info, Node: Command Line Editing, Next: Installing Bash, Prev: Using History Interactively, Up: Top
-Command Line Editing
-********************
+8 Command Line Editing
+**********************
- This chapter describes the basic features of the GNU command line
+This chapter describes the basic features of the GNU command line
editing interface. Command line editing is provided by the Readline
library, which is used by several different programs, including Bash.
\1f
File: bashref.info, Node: Introduction and Notation, Next: Readline Interaction, Up: Command Line Editing
-Introduction to Line Editing
-============================
+8.1 Introduction to Line Editing
+================================
- The following paragraphs describe the notation used to represent
+The following paragraphs describe the notation used to represent
keystrokes.
- The text <C-k> is read as `Control-K' and describes the character
+ The text `C-k' is read as `Control-K' and describes the character
produced when the <k> key is pressed while the Control key is depressed.
- The text <M-k> is read as `Meta-K' and describes the character
+ The text `M-k' is read as `Meta-K' and describes the character
produced when the Meta key (if you have one) is depressed, and the <k>
key is pressed. The Meta key is labeled <ALT> on many keyboards. On
keyboards with two keys labeled <ALT> (usually to either side of the
If you do not have a Meta or <ALT> key, or another key working as a
Meta key, the identical keystroke can be generated by typing <ESC>
-first, and then typing <k>. Either process is known as "metafying" the
-<k> key.
+_first_, and then typing <k>. Either process is known as "metafying"
+the <k> key.
- The text <M-C-k> is read as `Meta-Control-k' and describes the
-character produced by "metafying" <C-k>.
+ The text `M-C-k' is read as `Meta-Control-k' and describes the
+character produced by "metafying" `C-k'.
In addition, several keys have their own names. Specifically,
<DEL>, <ESC>, <LFD>, <SPC>, <RET>, and <TAB> all stand for themselves
-when seen in this text, or in an init file (*note Readline Init
-File::.). If your keyboard lacks a <LFD> key, typing <C-j> will
-produce the desired character. The <RET> key may be labeled <Return>
-or <Enter> on some keyboards.
+when seen in this text, or in an init file (*note Readline Init File::).
+If your keyboard lacks a <LFD> key, typing <C-j> will produce the
+desired character. The <RET> key may be labeled <Return> or <Enter> on
+some keyboards.
\1f
File: bashref.info, Node: Readline Interaction, Next: Readline Init File, Prev: Introduction and Notation, Up: Command Line Editing
-Readline Interaction
-====================
+8.2 Readline Interaction
+========================
- Often during an interactive session you type in a long line of text,
+Often during an interactive session you type in a long line of text,
only to notice that the first word on the line is misspelled. The
Readline library gives you a set of commands for manipulating the text
as you type it in, allowing you to just fix your typo, and not forcing
you to retype the majority of the line. Using these editing commands,
you move the cursor to the place that needs correction, and delete or
insert the text of the corrections. Then, when you are satisfied with
-the line, you simply press <RETURN>. You do not have to be at the end
-of the line to press <RETURN>; the entire line is accepted regardless
-of the location of the cursor within the line.
+the line, you simply press <RET>. You do not have to be at the end of
+the line to press <RET>; the entire line is accepted regardless of the
+location of the cursor within the line.
* Menu:
\1f
File: bashref.info, Node: Readline Bare Essentials, Next: Readline Movement Commands, Up: Readline Interaction
-Readline Bare Essentials
-------------------------
+8.2.1 Readline Bare Essentials
+------------------------------
- In order to enter characters into the line, simply type them. The
-typed character appears where the cursor was, and then the cursor moves
-one space to the right. If you mistype a character, you can use your
-erase character to back up and delete the mistyped character.
+In order to enter characters into the line, simply type them. The typed
+character appears where the cursor was, and then the cursor moves one
+space to the right. If you mistype a character, you can use your erase
+character to back up and delete the mistyped character.
Sometimes you may mistype a character, and not notice the error
until you have typed several other characters. In that case, you can
-type <C-b> to move the cursor to the left, and then correct your
-mistake. Afterwards, you can move the cursor to the right with <C-f>.
+type `C-b' to move the cursor to the left, and then correct your
+mistake. Afterwards, you can move the cursor to the right with `C-f'.
When you add text in the middle of a line, you will notice that
characters to the right of the cursor are `pushed over' to make room
list of the bare essentials for editing the text of an input line
follows.
-<C-b>
+`C-b'
Move back one character.
-<C-f>
+`C-f'
Move forward one character.
<DEL> or <Backspace>
Delete the character to the left of the cursor.
-<C-d>
+`C-d'
Delete the character underneath the cursor.
Printing characters
Insert the character into the line at the cursor.
-<C-_> or <C-x C-u>
+`C-_' or `C-x C-u'
Undo the last editing command. You can undo all the way back to an
empty line.
(Depending on your configuration, the <Backspace> key be set to delete
the character to the left of the cursor and the <DEL> key set to delete
-the character underneath the cursor, like <C-d>, rather than the
+the character underneath the cursor, like `C-d', rather than the
character to the left of the cursor.)
\1f
File: bashref.info, Node: Readline Movement Commands, Next: Readline Killing Commands, Prev: Readline Bare Essentials, Up: Readline Interaction
-Readline Movement Commands
---------------------------
+8.2.2 Readline Movement Commands
+--------------------------------
- The above table describes the most basic keystrokes that you need in
+The above table describes the most basic keystrokes that you need in
order to do editing of the input line. For your convenience, many
-other commands have been added in addition to <C-b>, <C-f>, <C-d>, and
+other commands have been added in addition to `C-b', `C-f', `C-d', and
<DEL>. Here are some commands for moving more rapidly about the line.
-<C-a>
+`C-a'
Move to the start of the line.
-<C-e>
+`C-e'
Move to the end of the line.
-<M-f>
+`M-f'
Move forward a word, where a word is composed of letters and
digits.
-<M-b>
+`M-b'
Move backward a word.
-<C-l>
+`C-l'
Clear the screen, reprinting the current line at the top.
- Notice how <C-f> moves forward a character, while <M-f> moves
+ Notice how `C-f' moves forward a character, while `M-f' moves
forward a word. It is a loose convention that control keystrokes
operate on characters while meta keystrokes operate on words.
\1f
File: bashref.info, Node: Readline Killing Commands, Next: Readline Arguments, Prev: Readline Movement Commands, Up: Readline Interaction
-Readline Killing Commands
--------------------------
+8.2.3 Readline Killing Commands
+-------------------------------
- "Killing" text means to delete the text from the line, but to save
-it away for later use, usually by "yanking" (re-inserting) it back into
+"Killing" text means to delete the text from the line, but to save it
+away for later use, usually by "yanking" (re-inserting) it back into
the line. (`Cut' and `paste' are more recent jargon for `kill' and
`yank'.)
Any number of consecutive kills save all of the killed text together, so
that when you yank it back, you get it all. The kill ring is not line
specific; the text that you killed on a previously typed line is
-available to be yanked back later, when you are typing another line.
+available to be yanked back later, when you are typing another line.
Here is the list of commands for killing text.
-<C-k>
+`C-k'
Kill the text from the current cursor position to the end of the
line.
-<M-d>
+`M-d'
Kill from the cursor to the end of the current word, or, if between
words, to the end of the next word. Word boundaries are the same
- as those used by <M-f>.
+ as those used by `M-f'.
-<M-DEL>
- Kill from the cursor the start of the previous word, or, if between
+`M-<DEL>'
+ Kill from the cursor the start of the current word, or, if between
words, to the start of the previous word. Word boundaries are the
- same as those used by <M-b>.
+ same as those used by `M-b'.
-<C-w>
+`C-w'
Kill from the cursor to the previous whitespace. This is
- different than <M-DEL> because the word boundaries differ.
+ different than `M-<DEL>' because the word boundaries differ.
+
Here is how to "yank" the text back into the line. Yanking means to
copy the most-recently-killed text from the kill buffer.
-<C-y>
+`C-y'
Yank the most recently killed text back into the buffer at the
cursor.
-<M-y>
+`M-y'
Rotate the kill-ring, and yank the new top. You can only do this
- if the prior command is <C-y> or <M-y>.
+ if the prior command is `C-y' or `M-y'.
\1f
File: bashref.info, Node: Readline Arguments, Next: Searching, Prev: Readline Killing Commands, Up: Readline Interaction
-Readline Arguments
-------------------
+8.2.4 Readline Arguments
+------------------------
- You can pass numeric arguments to Readline commands. Sometimes the
+You can pass numeric arguments to Readline commands. Sometimes the
argument acts as a repeat count, other times it is the sign of the
argument that is significant. If you pass a negative argument to a
command which normally acts in a forward direction, that command will
sign (`-'), then the sign of the argument will be negative. Once you
have typed one meta digit to get the argument started, you can type the
remainder of the digits, and then the command. For example, to give
-the <C-d> command an argument of 10, you could type `M-1 0 C-d'.
+the `C-d' command an argument of 10, you could type `M-1 0 C-d', which
+will delete the next ten characters on the input line.
\1f
File: bashref.info, Node: Searching, Prev: Readline Arguments, Up: Readline Interaction
-Searching for Commands in the History
--------------------------------------
+8.2.5 Searching for Commands in the History
+-------------------------------------------
- Readline provides commands for searching through the command history
-(*note Bash History Facilities::.) for lines containing a specified
-string. There are two search modes: INCREMENTAL and NON-INCREMENTAL.
+Readline provides commands for searching through the command history
+(*note Bash History Facilities::) for lines containing a specified
+string. There are two search modes: "incremental" and
+"non-incremental".
Incremental searches begin before the user has finished typing the
search string. As each character of the search string is typed,
Readline displays the next entry from the history matching the string
typed so far. An incremental search requires only as many characters
as needed to find the desired history entry. To search backward in the
-history for a particular string, type <C-r>. Typing <C-s> searches
+history for a particular string, type `C-r'. Typing `C-s' searches
forward through the history. The characters present in the value of
the `isearch-terminators' variable are used to terminate an incremental
search. If that variable has not been assigned a value, the <ESC> and
-<C-J> characters will terminate an incremental search. <C-g> will
+`C-J' characters will terminate an incremental search. `C-g' will
abort an incremental search and restore the original line. When the
search is terminated, the history entry containing the search string
becomes the current line.
- To find other matching entries in the history list, type <C-r> or
-<C-s> as appropriate. This will search backward or forward in the
+ To find other matching entries in the history list, type `C-r' or
+`C-s' as appropriate. This will search backward or forward in the
history for the next entry matching the search string typed so far.
Any other key sequence bound to a Readline command will terminate the
search and execute that command. For instance, a <RET> will terminate
the search and accept the line, thereby executing the command from the
-history list.
+history list. A movement command will terminate the search, make the
+last line found the current line, and begin editing.
+
+ Readline remembers the last incremental search string. If two
+`C-r's are typed without any intervening characters defining a new
+search string, any remembered search string is used.
Non-incremental searches read the entire search string before
starting to search for matching history lines. The search string may be
\1f
File: bashref.info, Node: Readline Init File, Next: Bindable Readline Commands, Prev: Readline Interaction, Up: Command Line Editing
-Readline Init File
-==================
+8.3 Readline Init File
+======================
- Although the Readline library comes with a set of Emacs-like
+Although the Readline library comes with a set of Emacs-like
keybindings installed by default, it is possible to use a different set
of keybindings. Any user can customize programs that use Readline by
putting commands in an "inputrc" file, conventionally in his home
\1f
File: bashref.info, Node: Readline Init File Syntax, Next: Conditional Init Constructs, Up: Readline Init File
-Readline Init File Syntax
--------------------------
+8.3.1 Readline Init File Syntax
+-------------------------------
- There are only a few basic constructs allowed in the Readline init
+There are only a few basic constructs allowed in the Readline init
file. Blank lines are ignored. Lines beginning with a `#' are
comments. Lines beginning with a `$' indicate conditional constructs
-(*note Conditional Init Constructs::.). Other lines denote variable
+(*note Conditional Init Constructs::). Other lines denote variable
settings and key bindings.
Variable Settings
You can modify the run-time behavior of Readline by altering the
values of variables in Readline using the `set' command within the
- init file. Here is how to change from the default Emacs-like key
- binding to use `vi' line editing commands:
+ init file. The syntax is simple:
+
+ set VARIABLE VALUE
+
+ Here, for example, is how to change from the default Emacs-like
+ key binding to use `vi' line editing commands:
set editing-mode vi
+ Variable names and values, where appropriate, are recognized
+ without regard to case.
+
The `bind -V' command lists the current Readline variable names
and values. *Note Bash Builtins::.
`completion-query-items'
The number of possible completions that determines when the
- user is asked whether he wants to see the list of
- possibilities. If the number of possible completions is
- greater than this value, Readline will ask the user whether
- or not he wishes to view them; otherwise, they are simply
- listed. The default limit is `100'.
+ user is asked whether the list of possibilities should be
+ displayed. If the number of possible completions is greater
+ than this value, Readline will ask the user whether or not he
+ wishes to view them; otherwise, they are simply listed. This
+ variable must be set to an integer value greater than or
+ equal to 0. The default limit is `100'.
`convert-meta'
If set to `on', Readline will convert characters with the
If set to `on', tilde expansion is performed when Readline
attempts word completion. The default is `off'.
+ If set to `on', the history code attempts to place point at
+ the same location on each history line retrieved with
+ `previous-history' or `next-history'.
+
`horizontal-scroll-mode'
This variable can be set to either `on' or `off'. Setting it
to `on' means that the text of the lines being edited will
`input-meta'
If set to `on', Readline will enable eight-bit input (it will
- not strip the eighth bit from the characters it reads),
+ not clear the eighth bit in the characters it reads),
regardless of what the terminal claims it can support. The
default value is `off'. The name `meta-flag' is a synonym
for this variable.
`isearch-terminators'
The string of characters that should terminate an incremental
search without subsequently executing the character as a
- command (*note Searching::.). If this variable has not been
- given a value, the characters <ESC> and <C-J> will terminate
+ command (*note Searching::). If this variable has not been
+ given a value, the characters <ESC> and `C-J' will terminate
an incremental search.
`keymap'
Sets Readline's idea of the current keymap for key binding
commands. Acceptable `keymap' names are `emacs',
- `emacs-standard', `emacs-meta', `emacs-ctlx', `vi',
+ `emacs-standard', `emacs-meta', `emacs-ctlx', `vi', `vi-move',
`vi-command', and `vi-insert'. `vi' is equivalent to
`vi-command'; `emacs' is equivalent to `emacs-standard'. The
default value is `emacs'. The value of the `editing-mode'
asterisk (`*') at the start of history lines which have been
modified. This variable is `off' by default.
+ `mark-symlinked-directories'
+ If set to `on', completed names which are symbolic links to
+ directories have a slash appended (subject to the value of
+ `mark-directories'). The default is `off'.
+
+ `match-hidden-files'
+ This variable, when set to `on', causes Readline to match
+ files whose names begin with a `.' (hidden files) when
+ performing filename completion, unless the leading `.' is
+ supplied by the user in the filename to be completed. This
+ variable is `on' by default.
+
`output-meta'
If set to `on', Readline will display characters with the
eighth bit set directly rather than as a meta-prefixed escape
sequence. The default is `off'.
+ `page-completions'
+ If set to `on', Readline uses an internal `more'-like pager
+ to display a screenful of possible completions at a time.
+ This variable is `on' by default.
+
`print-completions-horizontally'
If set to `on', Readline will display completions with matches
sorted horizontally in alphabetical order, rather than down
completion cause the matches to be listed immediately instead
of ringing the bell. The default value is `off'.
+ `show-all-if-unmodified'
+ This alters the default behavior of the completion functions
+ in a fashion similar to SHOW-ALL-IF-AMBIGUOUS. If set to
+ `on', words which have more than one possible completion
+ without any possible partial completion (the possible
+ completions don't share a common prefix) cause the matches to
+ be listed immediately instead of ringing the bell. The
+ default value is `off'.
+
`visible-stats'
If set to `on', a character denoting a file's type is
appended to the filename when listing possible completions.
The default is `off'.
+
Key Bindings
The syntax for controlling key bindings in the init file is
simple. First you need to find the name of the command that you
command name, the default keybinding, if any, and a short
description of what the command does.
- Once you know the name of the command, simply place the name of
- the key you wish to bind the command to, a colon, and then the
- name of the command on a line in the init file. The name of the
- key can be expressed in different ways, depending on which is most
- comfortable for you.
+ Once you know the name of the command, simply place on a line in
+ the init file the name of the key you wish to bind the command to,
+ a colon, and then the name of the command. The name of the key
+ can be expressed in different ways, depending on what you find most
+ comfortable.
+
+ In addition to command names, readline allows keys to be bound to
+ a string that is inserted when the key is pressed (a MACRO).
The `bind -p' command displays Readline function names and
bindings in a format that can put directly into an initialization
Meta-Rubout: backward-kill-word
Control-o: "> output"
- In the above example, <C-u> is bound to the function
- `universal-argument', and <C-o> is bound to run the macro
+ In the above example, `C-u' is bound to the function
+ `universal-argument', `M-DEL' is bound to the function
+ `backward-kill-word', and `C-o' is bound to run the macro
expressed on the right hand side (that is, to insert the text
`> output' into the line).
+ A number of symbolic character names are recognized while
+ processing this key binding syntax: DEL, ESC, ESCAPE, LFD,
+ NEWLINE, RET, RETURN, RUBOUT, SPACE, SPC, and TAB.
+
"KEYSEQ": FUNCTION-NAME or MACRO
KEYSEQ differs from KEYNAME above in that strings denoting an
entire key sequence can be specified, by placing the key
"\C-x\C-r": re-read-init-file
"\e[11~": "Function Key 1"
- In the above example, <C-u> is bound to the function
+ In the above example, `C-u' is again bound to the function
`universal-argument' (just as it was in the first example),
- `<C-x> <C-r>' is bound to the function `re-read-init-file',
- and `<ESC> <[> <1> <1> <~>' is bound to insert the text
- `Function Key 1'.
+ `C-x C-r' is bound to the function `re-read-init-file', and
+ `<ESC> <[> <1> <1> <~>' is bound to insert the text `Function
+ Key 1'.
+
The following GNU Emacs style escape sequences are available when
specifying key sequences:
vertical tab
`\NNN'
- the character whose `ASCII' code is the octal value NNN (one
- to three digits)
-
- `\xNNN'
- the character whose `ASCII' code is the hexadecimal value NNN
+ the eight-bit character whose value is the octal value NNN
(one to three digits)
+ `\xHH'
+ the eight-bit character whose value is the hexadecimal value
+ HH (one or two hex digits)
+
When entering the text of a macro, single or double quotes must be
used to indicate a macro definition. Unquoted text is assumed to
be a function name. In the macro body, the backslash escapes
the line:
"\C-x\\": "\\"
+
\1f
File: bashref.info, Node: Conditional Init Constructs, Next: Sample Init File, Prev: Readline Init File Syntax, Up: Readline Init File
-Conditional Init Constructs
----------------------------
+8.3.2 Conditional Init Constructs
+---------------------------------
- Readline implements a facility similar in spirit to the conditional
+Readline implements a facility similar in spirit to the conditional
compilation features of the C preprocessor which allows key bindings
and variable settings to be performed as the result of tests. There
are four parser directives used.
The APPLICATION construct is used to include
application-specific settings. Each program using the
Readline library sets the APPLICATION NAME, and you can test
- for it. This could be used to bind key sequences to
- functions useful for a specific program. For instance, the
- following command adds a key sequence that quotes the current
- or previous word in Bash:
+ for a particular value. This could be used to bind key
+ sequences to functions useful for a specific program. For
+ instance, the following command adds a key sequence that
+ quotes the current or previous word in Bash:
$if Bash
# Quote the current or previous word
"\C-xq": "\eb\"\ef\""
`$include'
This directive takes a single filename as an argument and reads
- commands and bindings from that file.
+ commands and bindings from that file. For example, the following
+ directive reads from `/etc/inputrc':
$include /etc/inputrc
\1f
File: bashref.info, Node: Sample Init File, Prev: Conditional Init Constructs, Up: Readline Init File
-Sample Init File
-----------------
+8.3.3 Sample Init File
+----------------------
- Here is an example of an inputrc file. This illustrates key
-binding, variable assignment, and conditional syntax.
+Here is an example of an INPUTRC file. This illustrates key binding,
+variable assignment, and conditional syntax.
# This file controls the behaviour of line input editing for
- # programs that use the Gnu Readline library. Existing programs
- # include FTP, Bash, and Gdb.
+ # programs that use the GNU Readline library. Existing
+ # programs include FTP, Bash, and GDB.
#
# You can re-read the inputrc file with C-x C-r.
# Lines beginning with '#' are comments.
#
- # First, include any systemwide bindings and variable assignments from
- # /etc/Inputrc
+ # First, include any systemwide bindings and variable
+ # assignments from /etc/Inputrc
$include /etc/Inputrc
-
+
#
# Set various bindings for emacs mode.
-
+
set editing-mode emacs
-
+
$if mode=emacs
-
+
Meta-Control-h: backward-kill-word Text after the function name is ignored
-
+
#
# Arrow keys in keypad mode
#
#"\M-\C-[C": forward-char
#"\M-\C-[A": previous-history
#"\M-\C-[B": next-history
-
+
C-q: quoted-insert
-
+
$endif
-
+
# An old-style binding. This happens to be the default.
TAB: complete
-
+
# Macros that are convenient for shell interaction
$if Bash
# edit the path
"\C-xp": "PATH=${PATH}\e\C-e\C-a\ef\C-f"
- # prepare to type a quoted word -- insert open and close double quotes
+ # prepare to type a quoted word --
+ # insert open and close double quotes
# and move to just after the open quote
"\C-x\"": "\"\"\C-b"
- # insert a backslash (testing backslash escapes in sequences and macros)
+ # insert a backslash (testing backslash escapes
+ # in sequences and macros)
"\C-x\\": "\\"
# Quote the current or previous word
"\C-xq": "\eb\"\ef\""
# Edit variable on current line.
"\M-\C-v": "\C-a\C-k$\C-y\M-\C-e\C-a\C-y="
$endif
-
+
# use a visible bell if one is available
set bell-style visible
-
+
# don't strip characters to 7 bits when reading
set input-meta on
-
- # allow iso-latin1 characters to be inserted rather than converted to
- # prefix-meta sequences
+
+ # allow iso-latin1 characters to be inserted rather
+ # than converted to prefix-meta sequences
set convert-meta off
-
- # display characters with the eighth bit set directly rather than
- # as meta-prefixed characters
+
+ # display characters with the eighth bit set directly
+ # rather than as meta-prefixed characters
set output-meta on
-
- # if there are more than 150 possible completions for a word, ask the
- # user if he wants to see all of them
+
+ # if there are more than 150 possible completions for
+ # a word, ask the user if he wants to see all of them
set completion-query-items 150
-
+
# For FTP
$if Ftp
"\C-xg": "get \M-?"
\1f
File: bashref.info, Node: Bindable Readline Commands, Next: Readline vi Mode, Prev: Readline Init File, Up: Command Line Editing
-Bindable Readline Commands
-==========================
+8.4 Bindable Readline Commands
+==============================
* Menu:
This section describes Readline commands that may be bound to key
sequences. You can list your key bindings by executing `bind -P' or,
for a more terse format, suitable for an INPUTRC file, `bind -p'.
-(*Note Bash Builtins::.)
+(*Note Bash Builtins::.) Command names without an accompanying key
+sequence are unbound by default.
- Command names without an accompanying key sequence are unbound by
-default. In the following descriptions, POINT refers to the current
-cursor position, and MARK refers to a cursor position saved by the
+ In the following descriptions, "point" refers to the current cursor
+position, and "mark" refers to a cursor position saved by the
`set-mark' command. The text between the point and mark is referred to
-as the REGION.
+as the "region".
\1f
File: bashref.info, Node: Commands For Moving, Next: Commands For History, Up: Bindable Readline Commands
-Commands For Moving
--------------------
+8.4.1 Commands For Moving
+-------------------------
`beginning-of-line (C-a)'
Move to the start of the current line.
`redraw-current-line ()'
Refresh the current line. By default, this is unbound.
+
\1f
File: bashref.info, Node: Commands For History, Next: Commands For Text, Prev: Commands For Moving, Up: Bindable Readline Commands
-Commands For Manipulating The History
--------------------------------------
+8.4.2 Commands For Manipulating The History
+-------------------------------------------
-`accept-line (Newline, Return)'
+`accept-line (Newline or Return)'
Accept the line regardless of where the cursor is. If this line is
non-empty, add it to the history list according to the setting of
- the `HISTCONTROL' and `HISTIGNORE' variables. If this line was a
- history line, then restore the history line to its original state.
+ the `HISTCONTROL' and `HISTIGNORE' variables. If this line is a
+ modified history line, then restore the history line to its
+ original state.
`previous-history (C-p)'
- Move `up' through the history list.
+ Move `back' through the history list, fetching the previous
+ command.
`next-history (C-n)'
- Move `down' through the history list.
+ Move `forward' through the history list, fetching the next command.
`beginning-of-history (M-<)'
Move to the first line in the history.
`yank-nth-arg (M-C-y)'
Insert the first argument to the previous command (usually the
- second word on the previous line). With an argument N, insert the
- Nth word from the previous command (the words in the previous
- command begin with word 0). A negative argument inserts the Nth
- word from the end of the previous command.
+ second word on the previous line) at point. With an argument N,
+ insert the Nth word from the previous command (the words in the
+ previous command begin with word 0). A negative argument inserts
+ the Nth word from the end of the previous command.
-`yank-last-arg (M-., M-_)'
+`yank-last-arg (M-. or M-_)'
Insert last argument to the previous command (the last word of the
previous history entry). With an argument, behave exactly like
`yank-nth-arg'. Successive calls to `yank-last-arg' move back
through the history list, inserting the last argument of each line
in turn.
+
\1f
File: bashref.info, Node: Commands For Text, Next: Commands For Killing, Prev: Commands For History, Up: Bindable Readline Commands
-Commands For Changing Text
---------------------------
+8.4.3 Commands For Changing Text
+--------------------------------
`delete-char (C-d)'
- Delete the character under the cursor. If the cursor is at the
- beginning of the line, there are no characters in the line, and
- the last character typed was not bound to `delete-char', then
- return `EOF'.
+ Delete the character at point. If point is at the beginning of
+ the line, there are no characters in the line, and the last
+ character typed was not bound to `delete-char', then return EOF.
`backward-delete-char (Rubout)'
Delete the character behind the cursor. A numeric argument means
end of the line, in which case the character behind the cursor is
deleted. By default, this is not bound to a key.
-`quoted-insert (C-q, C-v)'
+`quoted-insert (C-q or C-v)'
Add the next character typed to the line verbatim. This is how to
- insert key sequences like <C-q>, for example.
+ insert key sequences like `C-q', for example.
`self-insert (a, b, A, 1, !, ...)'
Insert yourself.
`transpose-words (M-t)'
Drag the word before point past the word after point, moving point
- past that word as well.
+ past that word as well. If the insertion point is at the end of
+ the line, this transposes the last two words on the line.
`upcase-word (M-u)'
Uppercase the current (or following) word. With a negative
Capitalize the current (or following) word. With a negative
argument, capitalize the previous word, but do not move the cursor.
+`overwrite-mode ()'
+ Toggle overwrite mode. With an explicit positive numeric argument,
+ switches to overwrite mode. With an explicit non-positive numeric
+ argument, switches to insert mode. This command affects only
+ `emacs' mode; `vi' mode does overwrite differently. Each call to
+ `readline()' starts in insert mode.
+
+ In overwrite mode, characters bound to `self-insert' replace the
+ text at point rather than pushing the text to the right.
+ Characters bound to `backward-delete-char' replace the character
+ before point with a space.
+
+ By default, this command is unbound.
+
+
\1f
File: bashref.info, Node: Commands For Killing, Next: Numeric Arguments, Prev: Commands For Text, Up: Bindable Readline Commands
-Killing And Yanking
--------------------
+8.4.4 Killing And Yanking
+-------------------------
`kill-line (C-k)'
Kill the text from point to the end of the line.
Kill backward from the cursor to the beginning of the current line.
`kill-whole-line ()'
- Kill all characters on the current line, no matter point is. By
- default, this is unbound.
+ Kill all characters on the current line, no matter where point is.
+ By default, this is unbound.
`kill-word (M-d)'
Kill from point to the end of the current word, or if between
words, to the end of the next word. Word boundaries are the same
as `forward-word'.
-`backward-kill-word (M-DEL)'
+`backward-kill-word (M-<DEL>)'
Kill the word behind point. Word boundaries are the same as
`backward-word'.
Kill the word behind point, using white space as a word boundary.
The killed text is saved on the kill-ring.
+`unix-filename-rubout ()'
+ Kill the word behind point, using white space and the slash
+ character as the word boundaries. The killed text is saved on the
+ kill-ring.
+
`delete-horizontal-space ()'
Delete all spaces and tabs around point. By default, this is
unbound.
command is unbound.
`yank (C-y)'
- Yank the top of the kill ring into the buffer at the current
- cursor position.
+ Yank the top of the kill ring into the buffer at point.
`yank-pop (M-y)'
Rotate the kill-ring, and yank the new top. You can only do this
- if the prior command is yank or yank-pop.
+ if the prior command is `yank' or `yank-pop'.
\1f
File: bashref.info, Node: Numeric Arguments, Next: Commands For Completion, Prev: Commands For Killing, Up: Bindable Readline Commands
-Specifying Numeric Arguments
-----------------------------
+8.4.5 Specifying Numeric Arguments
+----------------------------------
`digit-argument (M-0, M-1, ... M--)'
Add this digit to the argument already accumulating, or start a new
- argument. <M-> starts a negative argument.
+ argument. `M--' starts a negative argument.
`universal-argument ()'
This is another way to specify an argument. If this command is
\1f
File: bashref.info, Node: Commands For Completion, Next: Keyboard Macros, Prev: Numeric Arguments, Up: Bindable Readline Commands
-Letting Readline Type For You
------------------------------
+8.4.6 Letting Readline Type For You
+-----------------------------------
-`complete (TAB)'
- Attempt to do completion on the text before the cursor. This is
- application-specific. Generally, if you are typing a filename
- argument, you can do filename completion; if you are typing a
- command, you can do command completion; if you are typing in a
- symbol to GDB, you can do symbol name completion; if you are
- typing in a variable to Bash, you can do variable name completion,
- and so on. Bash attempts completion treating the text as a
- variable (if the text begins with `$'), username (if the text
- begins with `~'), hostname (if the text begins with `@'), or
- command (including aliases and functions) in turn. If none of
- these produces a match, filename completion is attempted.
+`complete (<TAB>)'
+ Attempt to perform completion on the text before point. The
+ actual completion performed is application-specific. Bash
+ attempts completion treating the text as a variable (if the text
+ begins with `$'), username (if the text begins with `~'), hostname
+ (if the text begins with `@'), or command (including aliases and
+ functions) in turn. If none of these produces a match, filename
+ completion is attempted.
`possible-completions (M-?)'
- List the possible completions of the text before the cursor.
+ List the possible completions of the text before point.
`insert-completions (M-*)'
Insert all completions of the text before point that would have
a single match from the list of possible completions. Repeated
execution of `menu-complete' steps through the list of possible
completions, inserting each match in turn. At the end of the list
- of completions, the bell is rung and the original text is restored.
- An argument of N moves N positions forward in the list of matches;
- a negative argument may be used to move backward through the list.
- This command is intended to be bound to `TAB', but is unbound by
+ of completions, the bell is rung (subject to the setting of
+ `bell-style') and the original text is restored. An argument of N
+ moves N positions forward in the list of matches; a negative
+ argument may be used to move backward through the list. This
+ command is intended to be bound to <TAB>, but is unbound by
default.
`delete-char-or-list ()'
List the possible completions of the text before point, treating
it as a command name.
-`dynamic-complete-history (M-TAB)'
+`dynamic-complete-history (M-<TAB>)'
Attempt completion on the text before point, comparing the text
against lines from the history list for possible completion
matches.
`complete-into-braces (M-{)'
Perform filename completion and insert the list of possible
completions enclosed within braces so the list is available to the
- shell (*note Brace Expansion::.).
+ shell (*note Brace Expansion::).
+
\1f
File: bashref.info, Node: Keyboard Macros, Next: Miscellaneous Commands, Prev: Commands For Completion, Up: Bindable Readline Commands
-Keyboard Macros
----------------
+8.4.7 Keyboard Macros
+---------------------
`start-kbd-macro (C-x ()'
Begin saving the characters typed into the current keyboard macro.
Re-execute the last keyboard macro defined, by making the
characters in the macro appear as if typed at the keyboard.
+
\1f
File: bashref.info, Node: Miscellaneous Commands, Prev: Keyboard Macros, Up: Bindable Readline Commands
-Some Miscellaneous Commands
----------------------------
+8.4.8 Some Miscellaneous Commands
+---------------------------------
`re-read-init-file (C-x C-r)'
Read in the contents of the INPUTRC file, and incorporate any
If the metafied character X is lowercase, run the command that is
bound to the corresponding uppercase character.
-`prefix-meta (ESC)'
- Make the next character typed be metafied. This is for keyboards
- without a meta key. Typing `ESC f' is equivalent to typing `M-f'.
+`prefix-meta (<ESC>)'
+ Metafy the next character typed. This is for keyboards without a
+ meta key. Typing `<ESC> f' is equivalent to typing `M-f'.
-`undo (C-_, C-x C-u)'
+`undo (C-_ or C-x C-u)'
Incremental undo, separately remembered for each line.
`revert-line (M-r)'
Perform tilde expansion on the current word.
`set-mark (C-@)'
- Set the mark to the current point. If a numeric argument is
- supplied, the mark is set to that position.
+ Set the mark to the point. If a numeric argument is supplied, the
+ mark is set to that position.
`exchange-point-and-mark (C-x C-x)'
Swap the point with the mark. The current cursor position is set
occurrences.
`insert-comment (M-#)'
- The value of the `comment-begin' variable is inserted at the
- beginning of the current line, and the line is accepted as if a
- newline had been typed. The default value of `comment-begin'
- causes this command to make the current line a shell comment.
+ Without a numeric argument, the value of the `comment-begin'
+ variable is inserted at the beginning of the current line. If a
+ numeric argument is supplied, this command acts as a toggle: if
+ the characters at the beginning of the line do not match the value
+ of `comment-begin', the value is inserted, otherwise the
+ characters in `comment-begin' are deleted from the beginning of
+ the line. In either case, the line is accepted as if a newline
+ had been typed. The default value of `comment-begin' causes this
+ command to make the current line a shell comment. If a numeric
+ argument causes the comment character to be removed, the line will
+ be executed by the shell.
`dump-functions ()'
Print all of the functions and their key bindings to the Readline
`dump-macros ()'
Print all of the Readline key sequences bound to macros and the
- strings they ouput. If a numeric argument is supplied, the output
- is formatted in such a way that it can be made part of an INPUTRC
- file. This command is unbound by default.
+ strings they output. If a numeric argument is supplied, the
+ output is formatted in such a way that it can be made part of an
+ INPUTRC file. This command is unbound by default.
+
+`glob-complete-word (M-g)'
+ The word before point is treated as a pattern for pathname
+ expansion, with an asterisk implicitly appended. This pattern is
+ used to generate a list of matching file names for possible
+ completions.
`glob-expand-word (C-x *)'
The word before point is treated as a pattern for pathname
expansion, and the list of matching file names is inserted,
- replacing the word.
+ replacing the word. If a numeric argument is supplied, a `*' is
+ appended before pathname expansion.
`glob-list-expansions (C-x g)'
The list of expansions that would have been generated by
- `glob-expand-word' is displayed, and the line is redrawn.
+ `glob-expand-word' is displayed, and the line is redrawn. If a
+ numeric argument is supplied, a `*' is appended before pathname
+ expansion.
`display-shell-version (C-x C-v)'
Display version information about the current instance of Bash.
`shell-expand-line (M-C-e)'
Expand the line as the shell does. This performs alias and
history expansion as well as all of the shell word expansions
- (*note Shell Expansions::.).
+ (*note Shell Expansions::).
`history-expand-line (M-^)'
Perform history expansion on the current line.
`magic-space ()'
Perform history expansion on the current line and insert a space
- (*note History Interaction::.).
+ (*note History Interaction::).
`alias-expand-line ()'
- Perform alias expansion on the current line (*note Aliases::.).
+ Perform alias expansion on the current line (*note Aliases::).
`history-and-alias-expand-line ()'
Perform history and alias expansion on the current line.
-`insert-last-argument (M-., M-_)'
+`insert-last-argument (M-. or M-_)'
A synonym for `yank-last-arg'.
`operate-and-get-next (C-o)'
relative to the current line from the history for editing. Any
argument is ignored.
-`emacs-editing-mode (C-e)'
- When in `vi' editing mode, this causes a switch back to `emacs'
- editing mode, as if the command `set -o emacs' had been executed.
+`edit-and-execute-command (C-xC-e)'
+ Invoke an editor on the current command line, and execute the
+ result as shell commands. Bash attempts to invoke `$VISUAL',
+ `$EDITOR', and `emacs' as the editor, in that order.
+
\1f
File: bashref.info, Node: Readline vi Mode, Next: Programmable Completion, Prev: Bindable Readline Commands, Up: Command Line Editing
-Readline vi Mode
-================
+8.5 Readline vi Mode
+====================
- While the Readline library does not have a full set of `vi' editing
+While the Readline library does not have a full set of `vi' editing
functions, it does contain enough to allow simple editing of the line.
The Readline `vi' mode behaves as specified in the POSIX 1003.2
standard.
In order to switch interactively between `emacs' and `vi' editing
modes, use the `set -o emacs' and `set -o vi' commands (*note The Set
-Builtin::.). The Readline default is `emacs' mode.
+Builtin::). The Readline default is `emacs' mode.
When you enter a line in `vi' mode, you are already placed in
`insertion' mode, as if you had typed an `i'. Pressing <ESC> switches
\1f
File: bashref.info, Node: Programmable Completion, Next: Programmable Completion Builtins, Prev: Readline vi Mode, Up: Command Line Editing
-Programmable Completion
-=======================
+8.6 Programmable Completion
+===========================
- When word completion is attempted for an argument to a command for
+When word completion is attempted for an argument to a command for
which a completion specification (a COMPSPEC) has been defined using
-the `complete' builtin (*note Programmable Completion Builtins::.), the
+the `complete' builtin (*note Programmable Completion Builtins::), the
programmable completion facilities are invoked.
First, the command name is identified. If a compspec has been
Once a compspec has been found, it is used to generate the list of
matching words. If a compspec is not found, the default Bash completion
-described above (*note Commands For Completion::.) is performed.
+described above (*note Commands For Completion::) is performed.
First, the actions specified by the compspec are used. Only matches
which are prefixed by the word being completed are returned. When the
special variable as delimiters. Shell quoting is honored. Each word
is then expanded using brace expansion, tilde expansion, parameter and
variable expansion, command substitution, arithmetic expansion, and
-pathname expansion, as described above (*note Shell Expansions::.).
-The results are split using the rules described above (*note Word
-Splitting::.). The results of the expansion are prefix-matched against
+pathname expansion, as described above (*note Shell Expansions::). The
+results are split using the rules described above (*note Word
+Splitting::). The results of the expansion are prefix-matched against
the word being completed, and the matching words become the possible
completions.
command specified with the `-F' and `-C' options is invoked. When the
command or function is invoked, the `COMP_LINE' and `COMP_POINT'
variables are assigned values as described above (*note Bash
-Variables::.). If a shell function is being invoked, the `COMP_WORDS'
+Variables::). If a shell function is being invoked, the `COMP_WORDS'
and `COMP_CWORD' variables are also set. When the function or command
is invoked, the first argument is the name of the command whose
arguments are being completed, the second argument is the word being
Any function specified with `-F' is invoked first. The function may
use any of the shell facilities, including the `compgen' builtin
-described below (*note Programmable Completion Builtins::.), to
-generate the matches. It must put the possible completions in the
-`COMPREPLY' array variable.
+described below (*note Programmable Completion Builtins::), to generate
+the matches. It must put the possible completions in the `COMPREPLY'
+array variable.
Next, any command specified with the `-C' option is invoked in an
environment equivalent to command substitution. It should print a list
is returned to the Readline completion code as the list of possible
completions.
- If a compspec is found, whatever it generates is returned to the
-completion code as the full set of possible completions. The default
-Bash completions are not attempted, and the Readline default of
-filename completion is disabled.
+ If the previously-applied actions do not generate any matches, and
+the `-o dirnames' option was supplied to `complete' when the compspec
+was defined, directory name completion is attempted.
+
+ If the `-o plusdirs' option was supplied to `complete' when the
+compspec was defined, directory name completion is attempted and any
+matches are added to the results of the other actions.
+
+ By default, if a compspec is found, whatever it generates is
+returned to the completion code as the full set of possible completions.
+The default Bash completions are not attempted, and the Readline default
+of filename completion is disabled. If the `-o bashdefault' option was
+supplied to `complete' when the compspec was defined, the default Bash
+completions are attempted if the compspec generates no matches. If the
+`-o default' option was supplied to `complete' when the compspec was
+defined, Readline's default completion will be performed if the
+compspec (and, if attempted, the default Bash completions) generate no
+matches.
+
+ When a compspec indicates that directory name completion is desired,
+the programmable completion functions force Readline to append a slash
+to completed names which are symbolic links to directories, subject to
+the value of the MARK-DIRECTORIES Readline variable, regardless of the
+setting of the MARK-SYMLINKED-DIRECTORIES Readline variable.
\1f
File: bashref.info, Node: Programmable Completion Builtins, Prev: Programmable Completion, Up: Command Line Editing
-Programmable Completion Builtins
-================================
+8.7 Programmable Completion Builtins
+====================================
- Two builtin commands are available to manipulate the programmable
+Two builtin commands are available to manipulate the programmable
completion facilities.
`compgen'
no matches were generated.
`complete'
- `complete [-abcdefjkvu] [-A ACTION] [-G GLOBPAT] [-W WORDLIST]
+ `complete [-abcdefgjksuv] [-o COMP-OPTION] [-A ACTION] [-G GLOBPAT] [-W WORDLIST]
[-P PREFIX] [-S SUFFIX] [-X FILTERPAT] [-F FUNCTION]
[-C COMMAND] NAME [NAME ...]'
`complete -pr [NAME ...]'
The process of applying these completion specifications when word
completion is attempted is described above (*note Programmable
- Completion::.).
+ Completion::).
Other options, if specified, have the following meanings. The
arguments to the `-G', `-W', and `-X' options (and, if necessary,
the `-P' and `-S' options) should be quoted to protect them from
expansion before the `complete' builtin is invoked.
+ `-o COMP-OPTION'
+ The COMP-OPTION controls several aspects of the compspec's
+ behavior beyond the simple generation of completions.
+ COMP-OPTION may be one of:
+
+ `bashdefault'
+ Perform the rest of the default Bash completions if the
+ compspec generates no matches.
+
+ `default'
+ Use Readline's default filename completion if the
+ compspec generates no matches.
+
+ `dirnames'
+ Perform directory name completion if the compspec
+ generates no matches.
+
+ `filenames'
+ Tell Readline that the compspec generates filenames, so
+ it can perform any filename-specific processing (like
+ adding a slash to directory names or suppressing
+ trailing spaces). This option is intended to be used
+ with shell functions specified with `-F'.
+
+ `nospace'
+ Tell Readline not to append a space (the default) to
+ words completed at the end of the line.
+
`-A ACTION'
The ACTION may be one of the following to generate a list of
possible completions:
`binding'
Readline key binding names (*note Bindable Readline
- Commands::.).
+ Commands::).
`builtin'
Names of shell builtin commands. May also be specified
`function'
Names of shell functions.
+ `group'
+ Group names. May also be specified as `-g'.
+
`helptopic'
Help topics as accepted by the `help' builtin (*note
- Bash Builtins::.).
+ Bash Builtins::).
`hostname'
Hostnames, as taken from the file specified by the
- `HOSTFILE' shell variable (*note Bash Variables::.).
+ `HOSTFILE' shell variable (*note Bash Variables::).
`job'
Job names, if job control is active. May also be
`running'
Names of running jobs, if job control is active.
+ `service'
+ Service names. May also be specified as `-s'.
+
`setopt'
Valid arguments for the `-o' option to the `set' builtin
- (*note The Set Builtin::.).
+ (*note The Set Builtin::).
`shopt'
Shell option names as accepted by the `shopt' builtin
- (*note Bash Builtins::.).
+ (*note Bash Builtins::).
`signal'
Signal names.
for a NAME for which no specification exists, or an error occurs
adding a completion specification.
+
\1f
File: bashref.info, Node: Using History Interactively, Next: Command Line Editing, Prev: Job Control, Up: Top
-Using History Interactively
-***************************
+9 Using History Interactively
+*****************************
- This chapter describes how to use the GNU History Library
+This chapter describes how to use the GNU History Library
interactively, from a user's standpoint. It should be considered a
user's guide. For information on using the GNU History Library in
other programs, see the GNU Readline Library Manual.
\1f
File: bashref.info, Node: Bash History Facilities, Next: Bash History Builtins, Up: Using History Interactively
-Bash History Facilities
-=======================
+9.1 Bash History Facilities
+===========================
- When the `-o history' option to the `set' builtin is enabled (*note
-The Set Builtin::.), the shell provides access to the COMMAND HISTORY,
-the list of commands previously typed. The value of the `HISTSIZE'
-shell variable is used as the number of commands to save in a history
-list. The text of the last `$HISTSIZE' commands (default 500) is saved.
-The shell stores each command in the history list prior to parameter
-and variable expansion but after history expansion is performed,
-subject to the values of the shell variables `HISTIGNORE' and
-`HISTCONTROL'.
+When the `-o history' option to the `set' builtin is enabled (*note The
+Set Builtin::), the shell provides access to the "command history", the
+list of commands previously typed. The value of the `HISTSIZE' shell
+variable is used as the number of commands to save in a history list.
+The text of the last `$HISTSIZE' commands (default 500) is saved. The
+shell stores each command in the history list prior to parameter and
+variable expansion but after history expansion is performed, subject to
+the values of the shell variables `HISTIGNORE' and `HISTCONTROL'.
When the shell starts up, the history is initialized from the file
named by the `HISTFILE' variable (default `~/.bash_history'). The file
`HISTFILESIZE' variable. When an interactive shell exits, the last
`$HISTSIZE' lines are copied from the history list to the file named by
`$HISTFILE'. If the `histappend' shell option is set (*note Bash
-Builtins::.), the lines are appended to the history file, otherwise the
+Builtins::), the lines are appended to the history file, otherwise the
history file is overwritten. If `HISTFILE' is unset, or if the history
file is unwritable, the history is not saved. After saving the
history, the history file is truncated to contain no more than
`$HISTFILESIZE' lines. If `HISTFILESIZE' is not set, no truncation is
performed.
+ If the `HISTTIMEFORMAT' is set, the time stamp information
+associated with each history entry is written to the history file.
+
The builtin command `fc' may be used to list or edit and re-execute
a portion of the history list. The `history' builtin may be used to
display or modify the history list and manipulate the history file.
When using command-line editing, search commands are available in each
editing mode that provide access to the history list (*note Commands
-For History::.).
+For History::).
The shell allows control over which commands are saved on the history
list. The `HISTCONTROL' and `HISTIGNORE' variables may be set to cause
\1f
File: bashref.info, Node: Bash History Builtins, Next: History Interaction, Prev: Bash History Facilities, Up: Using History Interactively
-Bash History Builtins
-=====================
+9.2 Bash History Builtins
+=========================
- Bash provides two builtin commands which manipulate the history list
+Bash provides two builtin commands which manipulate the history list
and history file.
`fc'
A useful alias to use with the `fc' command is `r='fc -s'', so
that typing `r cc' runs the last command beginning with `cc' and
- typing `r' re-executes the last command (*note Aliases::.).
+ typing `r' re-executes the last command (*note Aliases::).
`history'
history [N]
history -ps ARG
With no options, display the history list with line numbers.
- Lines prefixed with with a `*' have been modified. An argument of
- N lists only the last N lines. Options, if supplied, have the
- following meanings:
+ Lines prefixed with a `*' have been modified. An argument of N
+ lists only the last N lines. If the shell variable
+ `HISTTIMEFORMAT' is set and not null, it is used as a format
+ string for STRFTIME to display the time stamp associated with each
+ displayed history entry. No intervening blank is printed between
+ the formatted time stamp and the history line.
+
+ Options, if supplied, have the following meanings:
`-c'
Clear the history list. This may be combined with the other
The ARGs are added to the end of the history list as a single
entry.
+
When any of the `-w', `-r', `-a', or `-n' options is used, if
FILENAME is given, then it is used as the history file. If not,
then the value of the `HISTFILE' variable is used.
+
\1f
File: bashref.info, Node: History Interaction, Prev: Bash History Builtins, Up: Using History Interactively
-History Expansion
-=================
+9.3 History Expansion
+=====================
- The History library provides a history expansion feature that is
-similar to the history expansion provided by `csh'. This section
-describes the syntax used to manipulate the history information.
+The History library provides a history expansion feature that is similar
+to the history expansion provided by `csh'. This section describes the
+syntax used to manipulate the history information.
History expansions introduce words from the history list into the
input stream, making it easy to repeat commands, insert the arguments
Only `\' and `'' may be used to escape the history expansion character.
Several shell options settable with the `shopt' builtin (*note Bash
-Builtins::.) may be used to tailor the behavior of history expansion.
+Builtins::) may be used to tailor the behavior of history expansion.
If the `histverify' shell option is enabled, and Readline is being
used, history substitutions are not immediately passed to the shell
parser. Instead, the expanded line is reloaded into the Readline
\1f
File: bashref.info, Node: Event Designators, Next: Word Designators, Up: History Interaction
-Event Designators
------------------
+9.3.1 Event Designators
+-----------------------
- An event designator is a reference to a command line entry in the
-history list.
+An event designator is a reference to a command line entry in the
+history list.
`!'
Start a history substitution, except when followed by a space, tab,
- the end of the line, `=' or `('.
+ the end of the line, `=' or `(' (when the `extglob' shell option
+ is enabled using the `shopt' builtin).
`!N'
Refer to command line N.
`!#'
The entire command line typed so far.
+
\1f
File: bashref.info, Node: Word Designators, Next: Modifiers, Prev: Event Designators, Up: History Interaction
-Word Designators
-----------------
+9.3.2 Word Designators
+----------------------
- Word designators are used to select desired words from the event. A
+Word designators are used to select desired words from the event. A
`:' separates the event specification from the word designator. It may
be omitted if the word designator begins with a `^', `$', `*', `-', or
`%'. Words are numbered from the beginning of the line, with the first
`X-'
Abbreviates `X-$' like `X*', but omits the last word.
+
If a word designator is supplied without an event specification, the
previous command is used as the event.
\1f
File: bashref.info, Node: Modifiers, Prev: Word Designators, Up: History Interaction
-Modifiers
----------
+9.3.3 Modifiers
+---------------
- After the optional word designator, you can add a sequence of one or
+After the optional word designator, you can add a sequence of one or
more of the following modifiers, each preceded by a `:'.
`h'
Repeat the previous substitution.
`g'
+`a'
Cause changes to be applied over the entire event line. Used in
conjunction with `s', as in `gs/OLD/NEW/', or with `&'.
+`G'
+ Apply the following `s' modifier once to each word in the event.
+
+
\1f
File: bashref.info, Node: Installing Bash, Next: Reporting Bugs, Prev: Command Line Editing, Up: Top
-Installing Bash
-***************
+10 Installing Bash
+******************
- This chapter provides basic instructions for installing Bash on the
+This chapter provides basic instructions for installing Bash on the
various supported platforms. The distribution supports the GNU
operating systems, nearly every version of Unix, and several non-Unix
systems such as BeOS and Interix. Other independent ports exist for
-MS-DOS, OS/2, Windows 95/98, and Windows NT.
+MS-DOS, OS/2, and Windows platforms.
* Menu:
\1f
File: bashref.info, Node: Basic Installation, Next: Compilers and Options, Up: Installing Bash
-Basic Installation
-==================
+10.1 Basic Installation
+=======================
- These are installation instructions for Bash.
+These are installation instructions for Bash.
The simplest way to compile Bash is:
The file `configure.in' is used to create `configure' by a program
called Autoconf. You only need `configure.in' if you want to change it
or regenerate `configure' using a newer version of Autoconf. If you do
-this, make sure you are using Autoconf version 2.10 or newer.
-
- If you need to change `configure.in' or regenerate `configure', you
-will need to create two files: `_distribution' and `_patchlevel'.
-`_distribution' should contain the major and minor version numbers of
-the Bash distribution, for example `2.01'. `_patchlevel' should
-contain the patch level of the Bash distribution, `0' for example. The
-script `support/mkconffiles' has been provided to automate the creation
-of these files.
+this, make sure you are using Autoconf version 2.50 or newer.
You can remove the program binaries and object files from the source
code directory by typing `make clean'. To also remove the files that
\1f
File: bashref.info, Node: Compilers and Options, Next: Compiling For Multiple Architectures, Prev: Basic Installation, Up: Installing Bash
-Compilers and Options
-=====================
+10.2 Compilers and Options
+==========================
- Some systems require unusual options for compilation or linking that
+Some systems require unusual options for compilation or linking that
the `configure' script does not know about. You can give `configure'
initial values for variables by setting them in the environment. Using
a Bourne-compatible shell, you can do that on the command line like
\1f
File: bashref.info, Node: Compiling For Multiple Architectures, Next: Installation Names, Prev: Compilers and Options, Up: Installing Bash
-Compiling For Multiple Architectures
-====================================
+10.3 Compiling For Multiple Architectures
+=========================================
- You can compile Bash for more than one kind of computer at the same
+You can compile Bash for more than one kind of computer at the same
time, by placing the object files for each architecture in their own
directory. To do this, you must use a version of `make' that supports
the `VPATH' variable, such as GNU `make'. `cd' to the directory where
\1f
File: bashref.info, Node: Installation Names, Next: Specifying the System Type, Prev: Compiling For Multiple Architectures, Up: Installing Bash
-Installation Names
-==================
+10.4 Installation Names
+=======================
- By default, `make install' will install into `/usr/local/bin',
+By default, `make install' will install into `/usr/local/bin',
`/usr/local/man', etc. You can specify an installation prefix other
-than `/usr/local' by giving `configure' the option `--prefix=PATH'.
+than `/usr/local' by giving `configure' the option `--prefix=PATH', or
+by specifying a value for the `DESTDIR' `make' variable when running
+`make install'.
You can specify separate installation prefixes for
architecture-specific files and architecture-independent files. If you
\1f
File: bashref.info, Node: Specifying the System Type, Next: Sharing Defaults, Prev: Installation Names, Up: Installing Bash
-Specifying the System Type
-==========================
+10.5 Specifying the System Type
+===============================
- There may be some features `configure' can not figure out
-automatically, but needs to determine by the type of host Bash will run
+There may be some features `configure' can not figure out
+automatically, but need to determine by the type of host Bash will run
on. Usually `configure' can figure that out, but if it prints a
message saying it can not guess the host type, give it the
`--host=TYPE' option. `TYPE' can either be a short name for the system
type, such as `sun4', or a canonical name with three fields:
-`CPU-COMPANY-SYSTEM' (e.g., `sparc-sun-sunos4.1.2').
+`CPU-COMPANY-SYSTEM' (e.g., `i386-unknown-freebsd4.2').
See the file `support/config.sub' for the possible values of each
field.
\1f
File: bashref.info, Node: Sharing Defaults, Next: Operation Controls, Prev: Specifying the System Type, Up: Installing Bash
-Sharing Defaults
-================
+10.6 Sharing Defaults
+=====================
- If you want to set default values for `configure' scripts to share,
-you can create a site shell script called `config.site' that gives
-default values for variables like `CC', `cache_file', and `prefix'.
-`configure' looks for `PREFIX/share/config.site' if it exists, then
+If you want to set default values for `configure' scripts to share, you
+can create a site shell script called `config.site' that gives default
+values for variables like `CC', `cache_file', and `prefix'. `configure'
+looks for `PREFIX/share/config.site' if it exists, then
`PREFIX/etc/config.site' if it exists. Or, you can set the
`CONFIG_SITE' environment variable to the location of the site script.
A warning: the Bash `configure' looks for a site script, but not all
\1f
File: bashref.info, Node: Operation Controls, Next: Optional Features, Prev: Sharing Defaults, Up: Installing Bash
-Operation Controls
-==================
+10.7 Operation Controls
+=======================
- `configure' recognizes the following options to control how it
-operates.
+`configure' recognizes the following options to control how it operates.
`--cache-file=FILE'
Use and save the results of the tests in FILE instead of
\1f
File: bashref.info, Node: Optional Features, Prev: Operation Controls, Up: Installing Bash
-Optional Features
-=================
+10.8 Optional Features
+======================
- The Bash `configure' has a number of `--enable-FEATURE' options,
-where FEATURE indicates an optional part of Bash. There are also
-several `--with-PACKAGE' options, where PACKAGE is something like
-`bash-malloc' or `purify'. To turn off the default use of a package,
-use `--without-PACKAGE'. To configure Bash without a feature that is
+The Bash `configure' has a number of `--enable-FEATURE' options, where
+FEATURE indicates an optional part of Bash. There are also several
+`--with-PACKAGE' options, where PACKAGE is something like `bash-malloc'
+or `purify'. To turn off the default use of a package, use
+`--without-PACKAGE'. To configure Bash without a feature that is
enabled by default, use `--disable-FEATURE'.
Here is a complete list of the `--enable-' and `--with-' options
be supplied if your system has an inadequate or incomplete termcap
database.
-`--with-glibc-malloc'
- Use the GNU libc version of `malloc' in `lib/malloc/gmalloc.c'.
- This is not the version of `malloc' that appears in glibc version
- 2, but a modified version of the `malloc' from glibc version 1.
- This is somewhat slower than the default `malloc', but wastes less
- space on a per-allocation basis, and will return memory to the
- operating system under certain circumstances.
-
`--with-gnu-malloc'
A synonym for `--with-bash-malloc'.
-`--with-installed-readline'
+`--with-installed-readline[=PREFIX]'
Define this to make Bash link with a locally-installed version of
Readline rather than the version in `lib/readline'. This works
- only with Readline 4.1 and later versions.
+ only with Readline 4.3 and later versions. If PREFIX is `yes' or
+ not supplied, `configure' uses the values of the make variables
+ `includedir' and `libdir', which are subdirectories of `prefix' by
+ default, to find the installed version of Readline if it is not in
+ the standard system include and library directories. If PREFIX is
+ `no', Bash links with the version in `lib/readline'. If PREFIX is
+ set to any other value, `configure' treats it as a directory
+ pathname and looks for the installed version of Readline in
+ subdirectories of that directory (include files in
+ PREFIX/`include' and the library in PREFIX/`lib').
`--with-purify'
Define this to use the Purify memory allocation checker from
There are several `--enable-' options that alter how Bash is
compiled and linked, rather than changing run-time features.
+`--enable-largefile'
+ Enable support for large files
+ (http://www.sas.com/standards/large_file/x_open.20Mar96.html) if
+ the operating system requires special compiler options to build
+ programs which can access large files. This is enabled by
+ default, if the operating system provides large file support.
+
`--enable-profiling'
This builds a Bash binary that produces profiling information to be
processed by `gprof' each time it is executed.
`--enable-alias'
Allow alias expansion and include the `alias' and `unalias'
- builtins (*note Aliases::.).
+ builtins (*note Aliases::).
`--enable-arith-for-command'
Include support for the alternate form of the `for' command that
behaves like the C language `for' statement (*note Looping
- Constructs::.).
+ Constructs::).
`--enable-array-variables'
Include support for one-dimensional array shell variables (*note
- Arrays::.).
+ Arrays::).
`--enable-bang-history'
Include support for `csh'-like history substitution (*note History
- Interaction::.).
+ Interaction::).
`--enable-brace-expansion'
Include `csh'-like brace expansion ( `b{a,b}c' ==> `bac bbc' ).
`--enable-command-timing'
Include support for recognizing `time' as a reserved word and for
displaying timing statistics for the pipeline following `time'
- (*note Pipelines::.). This allows pipelines as well as shell
+ (*note Pipelines::). This allows pipelines as well as shell
builtins and functions to be timed.
`--enable-cond-command'
- Include support for the `[[' conditional command (*note
- Conditional Constructs::.).
+ Include support for the `[[' conditional command. (*note
+ Conditional Constructs::).
+
+`--enable-cond-regexp'
+ Include support for matching POSIX regular expressions using the
+ `=~' binary operator in the `[[' conditional command. (*note
+ Conditional Constructs::).
`--enable-directory-stack'
Include support for a `csh'-like directory stack and the `pushd',
- `popd', and `dirs' builtins (*note The Directory Stack::.).
+ `popd', and `dirs' builtins (*note The Directory Stack::).
`--enable-disabled-builtins'
Allow builtin commands to be invoked via `builtin xxx' even after
`--enable-dparen-arithmetic'
Include support for the `((...))' command (*note Conditional
- Constructs::.).
+ Constructs::).
`--enable-extended-glob'
Include support for the extended pattern matching features
`--enable-help-builtin'
Include the `help' builtin, which displays help on shell builtins
- and variables (*note Bash Builtins::.).
+ and variables (*note Bash Builtins::).
`--enable-history'
Include command history and the `fc' and `history' builtin
- commands (*note Bash History Facilities::.).
+ commands (*note Bash History Facilities::).
`--enable-job-control'
- This enables the job control features (*note Job Control::.), if
+ This enables the job control features (*note Job Control::), if
the operating system supports them.
+`--enable-multibyte'
+ This enables support for multibyte characters if the operating
+ system provides the necessary support.
+
`--enable-net-redirections'
This enables the special handling of filenames of the form
`/dev/tcp/HOST/PORT' and `/dev/udp/HOST/PORT' when used in
- redirections (*note Redirections::.).
+ redirections (*note Redirections::).
`--enable-process-substitution'
- This enables process substitution (*note Process Substitution::.)
- if the operating system provides the necessary support.
+ This enables process substitution (*note Process Substitution::) if
+ the operating system provides the necessary support.
`--enable-prompt-string-decoding'
Turn on the interpretation of a number of backslash-escaped
`--enable-progcomp'
Enable the programmable completion facilities (*note Programmable
- Completion::.). If Readline is not enabled, this option has no
+ Completion::). If Readline is not enabled, this option has no
effect.
`--enable-readline'
Include support for command-line editing and history with the Bash
- version of the Readline library (*note Command Line Editing::.).
+ version of the Readline library (*note Command Line Editing::).
`--enable-restricted'
Include support for a "restricted shell". If this is enabled,
`--enable-select'
Include the `select' builtin, which allows the generation of simple
- menus (*note Conditional Constructs::.).
+ menus (*note Conditional Constructs::).
`--enable-usg-echo-default'
A synonym for `--enable-xpg-echo-default'.
Specification, version 2. *Note Bash Builtins::, for a
description of the escape sequences that `echo' recognizes.
+
The file `config-top.h' contains C Preprocessor `#define' statements
for options which are not settable from `configure'. Some of these are
not meant to be changed; beware of the consequences if you do. Read
\1f
File: bashref.info, Node: Reporting Bugs, Next: Major Differences From The Bourne Shell, Prev: Installing Bash, Up: Top
-Reporting Bugs
-**************
+Appendix A Reporting Bugs
+*************************
- Please report all bugs you find in Bash. But first, you should make
+Please report all bugs you find in Bash. But first, you should make
sure that it really is a bug, and that it appears in the latest version
-of Bash that you have.
+of Bash. The latest version of Bash is always available for FTP from
+`ftp://ftp.gnu.org/pub/bash/'.
Once you have determined that a bug actually exists, use the
`bashbug' command to submit a bug report. If you have a fix, you are
Please send all reports concerning this manual to <chet@po.CWRU.Edu>.
\1f
-File: bashref.info, Node: Major Differences From The Bourne Shell, Next: Builtin Index, Prev: Reporting Bugs, Up: Top
+File: bashref.info, Node: Major Differences From The Bourne Shell, Next: Copying This Manual, Prev: Reporting Bugs, Up: Top
-Major Differences From The Bourne Shell
-***************************************
+Appendix B Major Differences From The Bourne Shell
+**************************************************
- Bash implements essentially the same grammar, parameter and variable
+Bash implements essentially the same grammar, parameter and variable
expansion, redirection, and quoting as the Bourne Shell. Bash uses the
POSIX 1003.2 standard as the specification of how these features are to
be implemented. There are some differences between the traditional
Bourne shell and Bash; this section quickly details the differences of
significance. A number of these differences are explained in greater
depth in previous sections. This section uses the version of `sh'
-included SVR4.2 as the baseline reference.
+included in SVR4.2 as the baseline reference.
* Bash is POSIX-conformant, even where the POSIX specification
- differs from traditional `sh' behavior.
+ differs from traditional `sh' behavior (*note Bash POSIX Mode::).
* Bash has multi-character invocation options (*note Invoking
- Bash::.).
+ Bash::).
- * Bash has command-line editing (*note Command Line Editing::.) and
+ * Bash has command-line editing (*note Command Line Editing::) and
the `bind' builtin.
* Bash provides a programmable word completion mechanism (*note
- Programmable Completion::.), and two builtin commands, `complete'
+ Programmable Completion::), and two builtin commands, `complete'
and `compgen', to manipulate it.
- * Bash has command history (*note Bash History Facilities::.) and the
- `history' and `fc' builtins to manipulate it.
+ * Bash has command history (*note Bash History Facilities::) and the
+ `history' and `fc' builtins to manipulate it. The Bash history
+ list maintains timestamp information and uses the value of the
+ `HISTTIMEFORMAT' variable to display it.
* Bash implements `csh'-like history expansion (*note History
- Interaction::.).
+ Interaction::).
- * Bash has one-dimensional array variables (*note Arrays::.), and the
+ * Bash has one-dimensional array variables (*note Arrays::), and the
appropriate variable expansions and assignment syntax to use them.
Several of the Bash builtins take options to act on arrays. Bash
provides a number of built-in array variables.
* The `$'...'' quoting syntax, which expands ANSI-C
backslash-escaped characters in the text between the single quotes,
- is supported (*note ANSI-C Quoting::.).
+ is supported (*note ANSI-C Quoting::).
* Bash supports the `$"..."' quoting syntax to do locale-specific
translation of the characters between the double quotes. The
`-D', `--dump-strings', and `--dump-po-strings' invocation options
list the translatable strings found in a script (*note Locale
- Translation::.).
+ Translation::).
* Bash implements the `!' keyword to negate the return value of a
- pipeline (*note Pipelines::.). Very useful when an `if' statement
+ pipeline (*note Pipelines::). Very useful when an `if' statement
needs to act only if a test fails.
* Bash has the `time' reserved word and command timing (*note
- Pipelines::.). The display of the timing statistics may be
+ Pipelines::). The display of the timing statistics may be
controlled with the `TIMEFORMAT' variable.
* Bash implements the `for (( EXPR1 ; EXPR2 ; EXPR3 ))' arithmetic
for command, similar to the C language (*note Looping
- Constructs::.).
+ Constructs::).
* Bash includes the `select' compound command, which allows the
- generation of simple menus (*note Conditional Constructs::.).
+ generation of simple menus (*note Conditional Constructs::).
* Bash includes the `[[' compound command, which makes conditional
- testing part of the shell grammar (*note Conditional
- Constructs::.).
+ testing part of the shell grammar (*note Conditional Constructs::).
- * Bash includes brace expansion (*note Brace Expansion::.) and tilde
- expansion (*note Tilde Expansion::.).
+ * Bash includes brace expansion (*note Brace Expansion::) and tilde
+ expansion (*note Tilde Expansion::).
* Bash implements command aliases and the `alias' and `unalias'
- builtins (*note Aliases::.).
+ builtins (*note Aliases::).
* Bash provides shell arithmetic, the `((' compound command (*note
- Conditional Constructs::.), and arithmetic expansion (*note Shell
- Arithmetic::.).
+ Conditional Constructs::), and arithmetic expansion (*note Shell
+ Arithmetic::).
* Variables present in the shell's initial environment are
automatically exported to child processes. The Bourne shell does
* Bash includes the POSIX pattern removal `%', `#', `%%' and `##'
expansions to remove leading or trailing substrings from variable
- values (*note Shell Parameter Expansion::.).
+ values (*note Shell Parameter Expansion::).
* The expansion `${#xx}', which returns the length of `${xx}', is
- supported (*note Shell Parameter Expansion::.).
+ supported (*note Shell Parameter Expansion::).
* The expansion `${var:'OFFSET`[:'LENGTH`]}', which expands to the
substring of `var''s value of length LENGTH, beginning at OFFSET,
- is present (*note Shell Parameter Expansion::.).
+ is present (*note Shell Parameter Expansion::).
* The expansion `${var/[/]'PATTERN`[/'REPLACEMENT`]}', which matches
PATTERN and replaces it with REPLACEMENT in the value of `var', is
- available (*note Shell Parameter Expansion::.).
+ available (*note Shell Parameter Expansion::).
* The expansion `${!PREFIX}*' expansion, which expands to the names
of all shell variables whose names begin with PREFIX, is available
- (*note Shell Parameter Expansion::.).
+ (*note Shell Parameter Expansion::).
* Bash has INDIRECT variable expansion using `${!word}' (*note Shell
- Parameter Expansion::.).
+ Parameter Expansion::).
* Bash can expand positional parameters beyond `$9' using `${NUM}'.
* The POSIX `$()' form of command substitution is implemented (*note
- Command Substitution::.), and preferred to the Bourne shell's ```'
+ Command Substitution::), and preferred to the Bourne shell's ```'
(which is also implemented for backwards compatibility).
- * Bash has process substitution (*note Process Substitution::.).
+ * Bash has process substitution (*note Process Substitution::).
* Bash automatically assigns variables that provide information
about the current user (`UID', `EUID', and `GROUPS'), the current
`BASH_VERSINFO'). *Note Bash Variables::, for details.
* The `IFS' variable is used to split only the results of expansion,
- not all words (*note Word Splitting::.). This closes a
+ not all words (*note Word Splitting::). This closes a
longstanding shell security hole.
* Bash implements the full set of POSIX 1003.2 filename expansion
operators, including CHARACTER CLASSES, EQUIVALENCE CLASSES, and
- COLLATING SYMBOLS (*note Filename Expansion::.).
+ COLLATING SYMBOLS (*note Filename Expansion::).
* Bash implements extended pattern matching features when the
- `extglob' shell option is enabled (*note Pattern Matching::.).
+ `extglob' shell option is enabled (*note Pattern Matching::).
* It is possible to have a variable and a function with the same
name; `sh' does not separate the two name spaces.
* Bash functions are permitted to have local variables using the
`local' builtin, and thus useful recursive functions may be written
- (*note Bash Builtins::.).
+ (*note Bash Builtins::).
* Variable assignments preceding commands affect only that command,
- even builtins and functions (*note Environment::.). In `sh', all
+ even builtins and functions (*note Environment::). In `sh', all
variable assignments preceding commands are global unless the
command is executed from the file system.
* Bash performs filename expansion on filenames specified as operands
- to input and output redirection operators (*note Redirections::.).
+ to input and output redirection operators (*note Redirections::).
* Bash contains the `<>' redirection operator, allowing a file to be
opened for both reading and writing, and the `&>' redirection
operator, for directing standard output and standard error to the
- same file (*note Redirections::.).
+ same file (*note Redirections::).
* Bash treats a number of filenames specially when they are used in
- redirection operators (*note Redirections::.).
+ redirection operators (*note Redirections::).
* Bash can open network connections to arbitrary machines and
- services with the redirection operators (*note Redirections::.).
+ services with the redirection operators (*note Redirections::).
* The `noclobber' option is available to avoid overwriting existing
- files with output redirection (*note The Set Builtin::.). The
- `>|' redirection operator may be used to override `noclobber'.
+ files with output redirection (*note The Set Builtin::). The `>|'
+ redirection operator may be used to override `noclobber'.
- * The Bash `cd' and `pwd' builtins (*note Bourne Shell Builtins::.)
- each take `-L' and `-P' builtins to switch between logical and
+ * The Bash `cd' and `pwd' builtins (*note Bourne Shell Builtins::)
+ each take `-L' and `-P' options to switch between logical and
physical modes.
* Bash allows a function to override a builtin with the same name,
and provides access to that builtin's functionality within the
function via the `builtin' and `command' builtins (*note Bash
- Builtins::.).
+ Builtins::).
* The `command' builtin allows selective disabling of functions when
- command lookup is performed (*note Bash Builtins::.).
+ command lookup is performed (*note Bash Builtins::).
* Individual builtins may be enabled or disabled using the `enable'
- builtin (*note Bash Builtins::.).
+ builtin (*note Bash Builtins::).
* The Bash `exec' builtin takes additional options that allow users
to control the contents of the environment passed to the executed
command, and what the zeroth argument to the command is to be
- (*note Bourne Shell Builtins::.).
+ (*note Bourne Shell Builtins::).
* Shell functions may be exported to children via the environment
- using `export -f' (*note Shell Functions::.).
+ using `export -f' (*note Shell Functions::).
* The Bash `export', `readonly', and `declare' builtins can take a
`-f' option to act on shell functions, a `-p' option to display
* The Bash `hash' builtin allows a name to be associated with an
arbitrary filename, even when that filename cannot be found by
searching the `$PATH', using `hash -p' (*note Bourne Shell
- Builtins::.).
+ Builtins::).
* Bash includes a `help' builtin for quick reference to shell
- facilities (*note Bash Builtins::.).
+ facilities (*note Bash Builtins::).
* The `printf' builtin is available to display formatted output
- (*note Bash Builtins::.).
+ (*note Bash Builtins::).
- * The Bash `read' builtin (*note Bash Builtins::.) will read a line
+ * The Bash `read' builtin (*note Bash Builtins::) will read a line
ending in `\' with the `-r' option, and will use the `REPLY'
variable as a default if no non-option arguments are supplied.
The Bash `read' builtin also accepts a prompt string with the `-p'
* The `return' builtin may be used to abort execution of scripts
executed with the `.' or `source' builtins (*note Bourne Shell
- Builtins::.).
+ Builtins::).
* Bash includes the `shopt' builtin, for finer control of shell
- optional capabilities (*note Bash Builtins::.).
+ optional capabilities (*note Bash Builtins::), and allows these
+ options to be set and unset at shell invocation (*note Invoking
+ Bash::).
* Bash has much more optional behavior controllable with the `set'
- builtin (*note The Set Builtin::.).
+ builtin (*note The Set Builtin::).
- * The `test' builtin (*note Bourne Shell Builtins::.) is slightly
+ * The `-x' (`xtrace') option displays commands other than simple
+ commands when performing an execution trace (*note The Set
+ Builtin::).
+
+ * The `test' builtin (*note Bourne Shell Builtins::) is slightly
different, as it implements the POSIX algorithm, which specifies
the behavior based on the number of arguments.
- * The `trap' builtin (*note Bourne Shell Builtins::.) allows a
+ * Bash includes the `caller' builtin, which displays the context of
+ any active subroutine call (a shell function or a script executed
+ with the `.' or `source' builtins). This supports the bash
+ debugger.
+
+ * The `trap' builtin (*note Bourne Shell Builtins::) allows a
`DEBUG' pseudo-signal specification, similar to `EXIT'. Commands
- specified with a `DEBUG' trap are executed after every simple
- command. The `DEBUG' trap is not inherited by shell functions.
+ specified with a `DEBUG' trap are executed before every simple
+ command, `for' command, `case' command, `select' command, every
+ arithmetic `for' command, and before the first command executes in
+ a shell function. The `DEBUG' trap is not inherited by shell
+ functions unless the function has been given the `trace' attribute
+ or the `functrace' option has been enabled using the `shopt'
+ builtin. The `extdebug' shell option has additional effects on the
+ `DEBUG' trap.
+
+ The `trap' builtin (*note Bourne Shell Builtins::) allows an `ERR'
+ pseudo-signal specification, similar to `EXIT' and `DEBUG'.
+ Commands specified with an `ERR' trap are executed after a simple
+ command fails, with a few exceptions. The `ERR' trap is not
+ inherited by shell functions unless the `-o errtrace' option to
+ the `set' builtin is enabled.
+
+ The `trap' builtin (*note Bourne Shell Builtins::) allows a
+ `RETURN' pseudo-signal specification, similar to `EXIT' and
+ `DEBUG'. Commands specified with an `RETURN' trap are executed
+ before execution resumes after a shell function or a shell script
+ executed with `.' or `source' returns. The `RETURN' trap is not
+ inherited by shell functions.
* The Bash `type' builtin is more extensive and gives more
- information about the names it finds (*note Bash Builtins::.).
+ information about the names it finds (*note Bash Builtins::).
* The Bash `umask' builtin permits a `-p' option to cause the output
to be displayed in the form of a `umask' command that may be
- reused as input (*note Bourne Shell Builtins::.).
+ reused as input (*note Bourne Shell Builtins::).
* Bash implements a `csh'-like directory stack, and provides the
`pushd', `popd', and `dirs' builtins to manipulate it (*note The
- Directory Stack::.). Bash also makes the directory stack visible
+ Directory Stack::). Bash also makes the directory stack visible
as the value of the `DIRSTACK' shell variable.
* Bash interprets special backslash-escaped characters in the prompt
- strings when interactive (*note Printing a Prompt::.).
+ strings when interactive (*note Printing a Prompt::).
* The Bash restricted mode is more useful (*note The Restricted
- Shell::.); the SVR4.2 shell restricted mode is too limited.
+ Shell::); the SVR4.2 shell restricted mode is too limited.
* The `disown' builtin can remove a job from the internal shell job
- table (*note Job Control Builtins::.) or suppress the sending of
+ table (*note Job Control Builtins::) or suppress the sending of
`SIGHUP' to a job when the shell exits as the result of a `SIGHUP'.
* The SVR4.2 shell has two privilege-related builtins (`mldmode' and
* The SVR4.2 `sh' uses a `TIMEOUT' variable like Bash uses `TMOUT'.
+
More features unique to Bash may be found in *Note Bash Features::.
-Implementation Differences From The SVR4.2 Shell
-================================================
+B.1 Implementation Differences From The SVR4.2 Shell
+====================================================
- Since Bash is a completely new implementation, it does not suffer
-from many of the limitations of the SVR4.2 shell. For instance:
+Since Bash is a completely new implementation, it does not suffer from
+many of the limitations of the SVR4.2 shell. For instance:
* Bash does not fork a subshell when redirecting into or out of a
shell control structure such as an `if' or `while' statement.
turns on job control).
\1f
-File: bashref.info, Node: Builtin Index, Next: Reserved Word Index, Prev: Major Differences From The Bourne Shell, Up: Top
+File: bashref.info, Node: Copying This Manual, Next: Builtin Index, Prev: Major Differences From The Bourne Shell, Up: Top
+
+Appendix C Copying This Manual
+******************************
+
+* Menu:
+
+* GNU Free Documentation License:: License for copying this manual.
+
+\1f
+File: bashref.info, Node: GNU Free Documentation License, Up: Copying This Manual
+
+C.1 GNU Free Documentation License
+==================================
+
+ Version 1.2, November 2002
+
+ Copyright (C) 2000,2001,2002 Free Software Foundation, Inc.
+ 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA
+
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+ 0. PREAMBLE
+
+ The purpose of this License is to make a manual, textbook, or other
+ functional and useful document "free" in the sense of freedom: to
+ assure everyone the effective freedom to copy and redistribute it,
+ with or without modifying it, either commercially or
+ noncommercially. Secondarily, this License preserves for the
+ author and publisher a way to get credit for their work, while not
+ being considered responsible for modifications made by others.
+
+ This License is a kind of "copyleft", which means that derivative
+ works of the document must themselves be free in the same sense.
+ It complements the GNU General Public License, which is a copyleft
+ license designed for free software.
+
+ We have designed this License in order to use it for manuals for
+ free software, because free software needs free documentation: a
+ free program should come with manuals providing the same freedoms
+ that the software does. But this License is not limited to
+ software manuals; it can be used for any textual work, regardless
+ of subject matter or whether it is published as a printed book.
+ We recommend this License principally for works whose purpose is
+ instruction or reference.
+
+ 1. APPLICABILITY AND DEFINITIONS
+
+ This License applies to any manual or other work, in any medium,
+ that contains a notice placed by the copyright holder saying it
+ can be distributed under the terms of this License. Such a notice
+ grants a world-wide, royalty-free license, unlimited in duration,
+ to use that work under the conditions stated herein. The
+ "Document", below, refers to any such manual or work. Any member
+ of the public is a licensee, and is addressed as "you". You
+ accept the license if you copy, modify or distribute the work in a
+ way requiring permission under copyright law.
+
+ A "Modified Version" of the Document means any work containing the
+ Document or a portion of it, either copied verbatim, or with
+ modifications and/or translated into another language.
+
+ A "Secondary Section" is a named appendix or a front-matter section
+ of the Document that deals exclusively with the relationship of the
+ publishers or authors of the Document to the Document's overall
+ subject (or to related matters) and contains nothing that could
+ fall directly within that overall subject. (Thus, if the Document
+ is in part a textbook of mathematics, a Secondary Section may not
+ explain any mathematics.) The relationship could be a matter of
+ historical connection with the subject or with related matters, or
+ of legal, commercial, philosophical, ethical or political position
+ regarding them.
+
+ The "Invariant Sections" are certain Secondary Sections whose
+ titles are designated, as being those of Invariant Sections, in
+ the notice that says that the Document is released under this
+ License. If a section does not fit the above definition of
+ Secondary then it is not allowed to be designated as Invariant.
+ The Document may contain zero Invariant Sections. If the Document
+ does not identify any Invariant Sections then there are none.
+
+ The "Cover Texts" are certain short passages of text that are
+ listed, as Front-Cover Texts or Back-Cover Texts, in the notice
+ that says that the Document is released under this License. A
+ Front-Cover Text may be at most 5 words, and a Back-Cover Text may
+ be at most 25 words.
+
+ A "Transparent" copy of the Document means a machine-readable copy,
+ represented in a format whose specification is available to the
+ general public, that is suitable for revising the document
+ straightforwardly with generic text editors or (for images
+ composed of pixels) generic paint programs or (for drawings) some
+ widely available drawing editor, and that is suitable for input to
+ text formatters or for automatic translation to a variety of
+ formats suitable for input to text formatters. A copy made in an
+ otherwise Transparent file format whose markup, or absence of
+ markup, has been arranged to thwart or discourage subsequent
+ modification by readers is not Transparent. An image format is
+ not Transparent if used for any substantial amount of text. A
+ copy that is not "Transparent" is called "Opaque".
+
+ Examples of suitable formats for Transparent copies include plain
+ ASCII without markup, Texinfo input format, LaTeX input format,
+ SGML or XML using a publicly available DTD, and
+ standard-conforming simple HTML, PostScript or PDF designed for
+ human modification. Examples of transparent image formats include
+ PNG, XCF and JPG. Opaque formats include proprietary formats that
+ can be read and edited only by proprietary word processors, SGML or
+ XML for which the DTD and/or processing tools are not generally
+ available, and the machine-generated HTML, PostScript or PDF
+ produced by some word processors for output purposes only.
+
+ The "Title Page" means, for a printed book, the title page itself,
+ plus such following pages as are needed to hold, legibly, the
+ material this License requires to appear in the title page. For
+ works in formats which do not have any title page as such, "Title
+ Page" means the text near the most prominent appearance of the
+ work's title, preceding the beginning of the body of the text.
+
+ A section "Entitled XYZ" means a named subunit of the Document
+ whose title either is precisely XYZ or contains XYZ in parentheses
+ following text that translates XYZ in another language. (Here XYZ
+ stands for a specific section name mentioned below, such as
+ "Acknowledgements", "Dedications", "Endorsements", or "History".)
+ To "Preserve the Title" of such a section when you modify the
+ Document means that it remains a section "Entitled XYZ" according
+ to this definition.
+
+ The Document may include Warranty Disclaimers next to the notice
+ which states that this License applies to the Document. These
+ Warranty Disclaimers are considered to be included by reference in
+ this License, but only as regards disclaiming warranties: any other
+ implication that these Warranty Disclaimers may have is void and
+ has no effect on the meaning of this License.
+
+ 2. VERBATIM COPYING
+
+ You may copy and distribute the Document in any medium, either
+ commercially or noncommercially, provided that this License, the
+ copyright notices, and the license notice saying this License
+ applies to the Document are reproduced in all copies, and that you
+ add no other conditions whatsoever to those of this License. You
+ may not use technical measures to obstruct or control the reading
+ or further copying of the copies you make or distribute. However,
+ you may accept compensation in exchange for copies. If you
+ distribute a large enough number of copies you must also follow
+ the conditions in section 3.
+
+ You may also lend copies, under the same conditions stated above,
+ and you may publicly display copies.
+
+ 3. COPYING IN QUANTITY
+
+ If you publish printed copies (or copies in media that commonly
+ have printed covers) of the Document, numbering more than 100, and
+ the Document's license notice requires Cover Texts, you must
+ enclose the copies in covers that carry, clearly and legibly, all
+ these Cover Texts: Front-Cover Texts on the front cover, and
+ Back-Cover Texts on the back cover. Both covers must also clearly
+ and legibly identify you as the publisher of these copies. The
+ front cover must present the full title with all words of the
+ title equally prominent and visible. You may add other material
+ on the covers in addition. Copying with changes limited to the
+ covers, as long as they preserve the title of the Document and
+ satisfy these conditions, can be treated as verbatim copying in
+ other respects.
+
+ If the required texts for either cover are too voluminous to fit
+ legibly, you should put the first ones listed (as many as fit
+ reasonably) on the actual cover, and continue the rest onto
+ adjacent pages.
+
+ If you publish or distribute Opaque copies of the Document
+ numbering more than 100, you must either include a
+ machine-readable Transparent copy along with each Opaque copy, or
+ state in or with each Opaque copy a computer-network location from
+ which the general network-using public has access to download
+ using public-standard network protocols a complete Transparent
+ copy of the Document, free of added material. If you use the
+ latter option, you must take reasonably prudent steps, when you
+ begin distribution of Opaque copies in quantity, to ensure that
+ this Transparent copy will remain thus accessible at the stated
+ location until at least one year after the last time you
+ distribute an Opaque copy (directly or through your agents or
+ retailers) of that edition to the public.
+
+ It is requested, but not required, that you contact the authors of
+ the Document well before redistributing any large number of
+ copies, to give them a chance to provide you with an updated
+ version of the Document.
+
+ 4. MODIFICATIONS
+
+ You may copy and distribute a Modified Version of the Document
+ under the conditions of sections 2 and 3 above, provided that you
+ release the Modified Version under precisely this License, with
+ the Modified Version filling the role of the Document, thus
+ licensing distribution and modification of the Modified Version to
+ whoever possesses a copy of it. In addition, you must do these
+ things in the Modified Version:
+
+ A. Use in the Title Page (and on the covers, if any) a title
+ distinct from that of the Document, and from those of
+ previous versions (which should, if there were any, be listed
+ in the History section of the Document). You may use the
+ same title as a previous version if the original publisher of
+ that version gives permission.
+
+ B. List on the Title Page, as authors, one or more persons or
+ entities responsible for authorship of the modifications in
+ the Modified Version, together with at least five of the
+ principal authors of the Document (all of its principal
+ authors, if it has fewer than five), unless they release you
+ from this requirement.
+
+ C. State on the Title page the name of the publisher of the
+ Modified Version, as the publisher.
+
+ D. Preserve all the copyright notices of the Document.
+
+ E. Add an appropriate copyright notice for your modifications
+ adjacent to the other copyright notices.
+
+ F. Include, immediately after the copyright notices, a license
+ notice giving the public permission to use the Modified
+ Version under the terms of this License, in the form shown in
+ the Addendum below.
+
+ G. Preserve in that license notice the full lists of Invariant
+ Sections and required Cover Texts given in the Document's
+ license notice.
+
+ H. Include an unaltered copy of this License.
+
+ I. Preserve the section Entitled "History", Preserve its Title,
+ and add to it an item stating at least the title, year, new
+ authors, and publisher of the Modified Version as given on
+ the Title Page. If there is no section Entitled "History" in
+ the Document, create one stating the title, year, authors,
+ and publisher of the Document as given on its Title Page,
+ then add an item describing the Modified Version as stated in
+ the previous sentence.
+
+ J. Preserve the network location, if any, given in the Document
+ for public access to a Transparent copy of the Document, and
+ likewise the network locations given in the Document for
+ previous versions it was based on. These may be placed in
+ the "History" section. You may omit a network location for a
+ work that was published at least four years before the
+ Document itself, or if the original publisher of the version
+ it refers to gives permission.
+
+ K. For any section Entitled "Acknowledgements" or "Dedications",
+ Preserve the Title of the section, and preserve in the
+ section all the substance and tone of each of the contributor
+ acknowledgements and/or dedications given therein.
+
+ L. Preserve all the Invariant Sections of the Document,
+ unaltered in their text and in their titles. Section numbers
+ or the equivalent are not considered part of the section
+ titles.
+
+ M. Delete any section Entitled "Endorsements". Such a section
+ may not be included in the Modified Version.
+
+ N. Do not retitle any existing section to be Entitled
+ "Endorsements" or to conflict in title with any Invariant
+ Section.
+
+ O. Preserve any Warranty Disclaimers.
+
+ If the Modified Version includes new front-matter sections or
+ appendices that qualify as Secondary Sections and contain no
+ material copied from the Document, you may at your option
+ designate some or all of these sections as invariant. To do this,
+ add their titles to the list of Invariant Sections in the Modified
+ Version's license notice. These titles must be distinct from any
+ other section titles.
+
+ You may add a section Entitled "Endorsements", provided it contains
+ nothing but endorsements of your Modified Version by various
+ parties--for example, statements of peer review or that the text
+ has been approved by an organization as the authoritative
+ definition of a standard.
+
+ You may add a passage of up to five words as a Front-Cover Text,
+ and a passage of up to 25 words as a Back-Cover Text, to the end
+ of the list of Cover Texts in the Modified Version. Only one
+ passage of Front-Cover Text and one of Back-Cover Text may be
+ added by (or through arrangements made by) any one entity. If the
+ Document already includes a cover text for the same cover,
+ previously added by you or by arrangement made by the same entity
+ you are acting on behalf of, you may not add another; but you may
+ replace the old one, on explicit permission from the previous
+ publisher that added the old one.
+
+ The author(s) and publisher(s) of the Document do not by this
+ License give permission to use their names for publicity for or to
+ assert or imply endorsement of any Modified Version.
+
+ 5. COMBINING DOCUMENTS
+
+ You may combine the Document with other documents released under
+ this License, under the terms defined in section 4 above for
+ modified versions, provided that you include in the combination
+ all of the Invariant Sections of all of the original documents,
+ unmodified, and list them all as Invariant Sections of your
+ combined work in its license notice, and that you preserve all
+ their Warranty Disclaimers.
+
+ The combined work need only contain one copy of this License, and
+ multiple identical Invariant Sections may be replaced with a single
+ copy. If there are multiple Invariant Sections with the same name
+ but different contents, make the title of each such section unique
+ by adding at the end of it, in parentheses, the name of the
+ original author or publisher of that section if known, or else a
+ unique number. Make the same adjustment to the section titles in
+ the list of Invariant Sections in the license notice of the
+ combined work.
+
+ In the combination, you must combine any sections Entitled
+ "History" in the various original documents, forming one section
+ Entitled "History"; likewise combine any sections Entitled
+ "Acknowledgements", and any sections Entitled "Dedications". You
+ must delete all sections Entitled "Endorsements."
+
+ 6. COLLECTIONS OF DOCUMENTS
+
+ You may make a collection consisting of the Document and other
+ documents released under this License, and replace the individual
+ copies of this License in the various documents with a single copy
+ that is included in the collection, provided that you follow the
+ rules of this License for verbatim copying of each of the
+ documents in all other respects.
+
+ You may extract a single document from such a collection, and
+ distribute it individually under this License, provided you insert
+ a copy of this License into the extracted document, and follow
+ this License in all other respects regarding verbatim copying of
+ that document.
+
+ 7. AGGREGATION WITH INDEPENDENT WORKS
+
+ A compilation of the Document or its derivatives with other
+ separate and independent documents or works, in or on a volume of
+ a storage or distribution medium, is called an "aggregate" if the
+ copyright resulting from the compilation is not used to limit the
+ legal rights of the compilation's users beyond what the individual
+ works permit. When the Document is included an aggregate, this
+ License does not apply to the other works in the aggregate which
+ are not themselves derivative works of the Document.
+
+ If the Cover Text requirement of section 3 is applicable to these
+ copies of the Document, then if the Document is less than one half
+ of the entire aggregate, the Document's Cover Texts may be placed
+ on covers that bracket the Document within the aggregate, or the
+ electronic equivalent of covers if the Document is in electronic
+ form. Otherwise they must appear on printed covers that bracket
+ the whole aggregate.
+
+ 8. TRANSLATION
+
+ Translation is considered a kind of modification, so you may
+ distribute translations of the Document under the terms of section
+ 4. Replacing Invariant Sections with translations requires special
+ permission from their copyright holders, but you may include
+ translations of some or all Invariant Sections in addition to the
+ original versions of these Invariant Sections. You may include a
+ translation of this License, and all the license notices in the
+ Document, and any Warranty Disclaimers, provided that you also
+ include the original English version of this License and the
+ original versions of those notices and disclaimers. In case of a
+ disagreement between the translation and the original version of
+ this License or a notice or disclaimer, the original version will
+ prevail.
+
+ If a section in the Document is Entitled "Acknowledgements",
+ "Dedications", or "History", the requirement (section 4) to
+ Preserve its Title (section 1) will typically require changing the
+ actual title.
+
+ 9. TERMINATION
+
+ You may not copy, modify, sublicense, or distribute the Document
+ except as expressly provided for under this License. Any other
+ attempt to copy, modify, sublicense or distribute the Document is
+ void, and will automatically terminate your rights under this
+ License. However, parties who have received copies, or rights,
+ from you under this License will not have their licenses
+ terminated so long as such parties remain in full compliance.
+
+ 10. FUTURE REVISIONS OF THIS LICENSE
+
+ The Free Software Foundation may publish new, revised versions of
+ the GNU Free Documentation License from time to time. Such new
+ versions will be similar in spirit to the present version, but may
+ differ in detail to address new problems or concerns. See
+ `http://www.gnu.org/copyleft/'.
+
+ Each version of the License is given a distinguishing version
+ number. If the Document specifies that a particular numbered
+ version of this License "or any later version" applies to it, you
+ have the option of following the terms and conditions either of
+ that specified version or of any later version that has been
+ published (not as a draft) by the Free Software Foundation. If
+ the Document does not specify a version number of this License,
+ you may choose any version ever published (not as a draft) by the
+ Free Software Foundation.
+
+C.1.1 ADDENDUM: How to use this License for your documents
+----------------------------------------------------------
+
+To use this License in a document you have written, include a copy of
+the License in the document and put the following copyright and license
+notices just after the title page:
+
+ Copyright (C) YEAR YOUR NAME.
+ Permission is granted to copy, distribute and/or modify this document
+ under the terms of the GNU Free Documentation License, Version 1.2
+ or any later version published by the Free Software Foundation;
+ with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
+ A copy of the license is included in the section entitled ``GNU
+ Free Documentation License''.
+
+ If you have Invariant Sections, Front-Cover Texts and Back-Cover
+Texts, replace the "with...Texts." line with this:
+
+ with the Invariant Sections being LIST THEIR TITLES, with
+ the Front-Cover Texts being LIST, and with the Back-Cover Texts
+ being LIST.
+
+ If you have Invariant Sections without Cover Texts, or some other
+combination of the three, merge those two alternatives to suit the
+situation.
+
+ If your document contains nontrivial examples of program code, we
+recommend releasing these examples in parallel under your choice of
+free software license, such as the GNU General Public License, to
+permit their use in free software.
+
+\1f
+File: bashref.info, Node: Builtin Index, Next: Reserved Word Index, Prev: Copying This Manual, Up: Top
Index of Shell Builtin Commands
*******************************
+\0\b[index\0\b]
* Menu:
* .: Bourne Shell Builtins.
+ (line 16)
* :: Bourne Shell Builtins.
+ (line 11)
* [: Bourne Shell Builtins.
-* alias: Bash Builtins.
+ (line 212)
+* alias: Bash Builtins. (line 11)
* bg: Job Control Builtins.
-* bind: Bash Builtins.
+ (line 7)
+* bind: Bash Builtins. (line 21)
* break: Bourne Shell Builtins.
-* builtin: Bash Builtins.
+ (line 29)
+* builtin: Bash Builtins. (line 92)
+* caller: Bash Builtins. (line 100)
* cd: Bourne Shell Builtins.
-* command: Bash Builtins.
+ (line 36)
+* command: Bash Builtins. (line 117)
* compgen: Programmable Completion Builtins.
+ (line 10)
* complete: Programmable Completion Builtins.
+ (line 28)
* continue: Bourne Shell Builtins.
-* declare: Bash Builtins.
+ (line 55)
+* declare: Bash Builtins. (line 136)
* dirs: Directory Stack Builtins.
+ (line 7)
* disown: Job Control Builtins.
-* echo: Bash Builtins.
-* enable: Bash Builtins.
+ (line 83)
+* echo: Bash Builtins. (line 191)
+* enable: Bash Builtins. (line 244)
* eval: Bourne Shell Builtins.
+ (line 63)
* exec: Bourne Shell Builtins.
+ (line 70)
* exit: Bourne Shell Builtins.
+ (line 82)
* export: Bourne Shell Builtins.
+ (line 88)
* fc: Bash History Builtins.
+ (line 10)
* fg: Job Control Builtins.
+ (line 16)
* getopts: Bourne Shell Builtins.
+ (line 103)
* hash: Bourne Shell Builtins.
-* help: Bash Builtins.
+ (line 145)
+* help: Bash Builtins. (line 272)
* history: Bash History Builtins.
+ (line 39)
* jobs: Job Control Builtins.
+ (line 25)
* kill: Job Control Builtins.
-* let: Bash Builtins.
-* local: Bash Builtins.
-* logout: Bash Builtins.
+ (line 57)
+* let: Bash Builtins. (line 281)
+* local: Bash Builtins. (line 288)
+* logout: Bash Builtins. (line 298)
* popd: Directory Stack Builtins.
-* printf: Bash Builtins.
+ (line 37)
+* printf: Bash Builtins. (line 302)
* pushd: Directory Stack Builtins.
+ (line 58)
* pwd: Bourne Shell Builtins.
-* read: Bash Builtins.
+ (line 163)
+* read: Bash Builtins. (line 324)
* readonly: Bourne Shell Builtins.
+ (line 172)
* return: Bourne Shell Builtins.
-* set: The Set Builtin.
+ (line 187)
+* set: The Set Builtin. (line 9)
* shift: Bourne Shell Builtins.
-* shopt: Bash Builtins.
-* source: Bash Builtins.
+ (line 200)
+* shopt: Bash Builtins. (line 385)
+* source: Bash Builtins. (line 600)
* suspend: Job Control Builtins.
+ (line 94)
* test: Bourne Shell Builtins.
+ (line 212)
* times: Bourne Shell Builtins.
+ (line 276)
* trap: Bourne Shell Builtins.
-* type: Bash Builtins.
-* typeset: Bash Builtins.
-* ulimit: Bash Builtins.
+ (line 281)
+* type: Bash Builtins. (line 604)
+* typeset: Bash Builtins. (line 635)
+* ulimit: Bash Builtins. (line 641)
* umask: Bourne Shell Builtins.
-* unalias: Bash Builtins.
+ (line 322)
+* unalias: Bash Builtins. (line 703)
* unset: Bourne Shell Builtins.
+ (line 339)
* wait: Job Control Builtins.
+ (line 73)
\1f
File: bashref.info, Node: Reserved Word Index, Next: Variable Index, Prev: Builtin Index, Up: Top
Index of Shell Reserved Words
*****************************
+\0\b[index\0\b]
* Menu:
-* !: Pipelines.
+* !: Pipelines. (line 8)
* [[: Conditional Constructs.
+ (line 105)
* ]]: Conditional Constructs.
+ (line 105)
* case: Conditional Constructs.
-* do: Looping Constructs.
-* done: Looping Constructs.
+ (line 28)
+* do: Looping Constructs. (line 12)
+* done: Looping Constructs. (line 12)
* elif: Conditional Constructs.
+ (line 7)
* else: Conditional Constructs.
+ (line 7)
* esac: Conditional Constructs.
+ (line 28)
* fi: Conditional Constructs.
-* for: Looping Constructs.
-* function: Shell Functions.
+ (line 7)
+* for: Looping Constructs. (line 29)
+* function: Shell Functions. (line 13)
* if: Conditional Constructs.
+ (line 7)
* in: Conditional Constructs.
+ (line 28)
* select: Conditional Constructs.
+ (line 64)
* then: Conditional Constructs.
-* time: Pipelines.
-* until: Looping Constructs.
-* while: Looping Constructs.
-* {: Command Grouping.
-* }: Command Grouping.
+ (line 7)
+* time: Pipelines. (line 8)
+* until: Looping Constructs. (line 12)
+* while: Looping Constructs. (line 20)
+* {: Command Grouping. (line 21)
+* }: Command Grouping. (line 21)
\1f
File: bashref.info, Node: Variable Index, Next: Function Index, Prev: Reserved Word Index, Up: Top
Parameter and Variable Index
****************************
+\0\b[index\0\b]
* Menu:
-* !: Special Parameters.
-* #: Special Parameters.
-* $: Special Parameters.
-* *: Special Parameters.
-* -: Special Parameters.
-* 0: Special Parameters.
-* ?: Special Parameters.
-* @: Special Parameters.
-* _: Special Parameters.
+* !: Special Parameters. (line 42)
+* #: Special Parameters. (line 26)
+* $: Special Parameters. (line 38)
+* *: Special Parameters. (line 9)
+* -: Special Parameters. (line 33)
+* 0: Special Parameters. (line 46)
+* ?: Special Parameters. (line 29)
+* @: Special Parameters. (line 19)
+* _: Special Parameters. (line 55)
* auto_resume: Job Control Variables.
-* BASH: Bash Variables.
-* BASH_ENV: Bash Variables.
-* BASH_VERSINFO: Bash Variables.
-* BASH_VERSION: Bash Variables.
+ (line 6)
+* BASH: Bash Variables. (line 13)
+* BASH_ARGC: Bash Variables. (line 16)
+* BASH_ARGV: Bash Variables. (line 24)
+* BASH_COMMAND: Bash Variables. (line 31)
+* BASH_ENV: Bash Variables. (line 36)
+* BASH_EXECUTION_STRING: Bash Variables. (line 42)
+* BASH_LINENO: Bash Variables. (line 45)
+* BASH_REMATCH: Bash Variables. (line 53)
+* BASH_SOURCE: Bash Variables. (line 61)
+* BASH_SUBSHELL: Bash Variables. (line 65)
+* BASH_VERSINFO: Bash Variables. (line 69)
+* BASH_VERSION: Bash Variables. (line 93)
* bell-style: Readline Init File Syntax.
+ (line 34)
* CDPATH: Bourne Shell Variables.
+ (line 9)
+* COLUMNS: Bash Variables. (line 96)
* comment-begin: Readline Init File Syntax.
-* COMP_CWORD: Bash Variables.
-* COMP_LINE: Bash Variables.
-* COMP_POINT: Bash Variables.
-* COMP_WORDS: Bash Variables.
+ (line 41)
+* COMP_CWORD: Bash Variables. (line 101)
+* COMP_LINE: Bash Variables. (line 107)
+* COMP_POINT: Bash Variables. (line 112)
+* COMP_WORDBREAKS: Bash Variables. (line 120)
+* COMP_WORDS: Bash Variables. (line 126)
* completion-query-items: Readline Init File Syntax.
-* COMPREPLY: Bash Variables.
+ (line 51)
+* COMPREPLY: Bash Variables. (line 132)
* convert-meta: Readline Init File Syntax.
-* DIRSTACK: Bash Variables.
+ (line 60)
+* DIRSTACK: Bash Variables. (line 137)
* disable-completion: Readline Init File Syntax.
+ (line 66)
* editing-mode: Readline Init File Syntax.
+ (line 71)
+* EMACS: Bash Variables. (line 147)
* enable-keypad: Readline Init File Syntax.
-* EUID: Bash Variables.
+ (line 77)
+* EUID: Bash Variables. (line 152)
* expand-tilde: Readline Init File Syntax.
-* FCEDIT: Bash Variables.
-* FIGNORE: Bash Variables.
-* FUNCNAME: Bash Variables.
-* GLOBIGNORE: Bash Variables.
-* GROUPS: Bash Variables.
-* histchars: Bash Variables.
-* HISTCMD: Bash Variables.
-* HISTCONTROL: Bash Variables.
-* HISTFILE: Bash Variables.
-* HISTFILESIZE: Bash Variables.
-* HISTIGNORE: Bash Variables.
-* HISTSIZE: Bash Variables.
+ (line 82)
+* FCEDIT: Bash Variables. (line 156)
+* FIGNORE: Bash Variables. (line 160)
+* FUNCNAME: Bash Variables. (line 166)
+* GLOBIGNORE: Bash Variables. (line 175)
+* GROUPS: Bash Variables. (line 181)
+* histchars: Bash Variables. (line 187)
+* HISTCMD: Bash Variables. (line 202)
+* HISTCONTROL: Bash Variables. (line 207)
+* HISTFILE: Bash Variables. (line 223)
+* HISTFILESIZE: Bash Variables. (line 227)
+* HISTIGNORE: Bash Variables. (line 234)
+* history-preserve-point: Readline Init File Syntax.
+ (line 85)
+* HISTSIZE: Bash Variables. (line 253)
+* HISTTIMEFORMAT: Bash Variables. (line 257)
* HOME: Bourne Shell Variables.
+ (line 13)
* horizontal-scroll-mode: Readline Init File Syntax.
-* HOSTFILE: Bash Variables.
-* HOSTNAME: Bash Variables.
-* HOSTTYPE: Bash Variables.
+ (line 90)
+* HOSTFILE: Bash Variables. (line 264)
+* HOSTNAME: Bash Variables. (line 275)
+* HOSTTYPE: Bash Variables. (line 278)
* IFS: Bourne Shell Variables.
-* IGNOREEOF: Bash Variables.
+ (line 18)
+* IGNOREEOF: Bash Variables. (line 281)
* input-meta: Readline Init File Syntax.
-* INPUTRC: Bash Variables.
+ (line 97)
+* INPUTRC: Bash Variables. (line 291)
* isearch-terminators: Readline Init File Syntax.
+ (line 104)
* keymap: Readline Init File Syntax.
-* LANG: Bash Variables.
-* LC_ALL: Bash Variables.
-* LC_COLLATE: Bash Variables.
-* LC_CTYPE: Bash Variables.
-* LC_MESSAGES: Bash Variables.
-* LC_NUMERIC: Bash Variables.
-* LINENO: Bash Variables.
-* MACHTYPE: Bash Variables.
+ (line 111)
+* LANG: Bash Variables. (line 295)
+* LC_ALL: Bash Variables. (line 299)
+* LC_COLLATE: Bash Variables. (line 303)
+* LC_CTYPE: Bash Variables. (line 310)
+* LC_MESSAGES <1>: Locale Translation. (line 11)
+* LC_MESSAGES: Bash Variables. (line 315)
+* LC_NUMERIC: Bash Variables. (line 319)
+* LINENO: Bash Variables. (line 323)
+* LINES: Bash Variables. (line 327)
+* MACHTYPE: Bash Variables. (line 332)
* MAIL: Bourne Shell Variables.
-* MAILCHECK: Bash Variables.
+ (line 22)
+* MAILCHECK: Bash Variables. (line 336)
* MAILPATH: Bourne Shell Variables.
+ (line 27)
* mark-modified-lines: Readline Init File Syntax.
+ (line 124)
+* mark-symlinked-directories: Readline Init File Syntax.
+ (line 129)
+* match-hidden-files: Readline Init File Syntax.
+ (line 134)
* meta-flag: Readline Init File Syntax.
-* OLDPWD: Bash Variables.
+ (line 97)
+* OLDPWD: Bash Variables. (line 344)
* OPTARG: Bourne Shell Variables.
-* OPTERR: Bash Variables.
+ (line 34)
+* OPTERR: Bash Variables. (line 347)
* OPTIND: Bourne Shell Variables.
-* OSTYPE: Bash Variables.
+ (line 38)
+* OSTYPE: Bash Variables. (line 351)
* output-meta: Readline Init File Syntax.
+ (line 141)
+* page-completions: Readline Init File Syntax.
+ (line 146)
* PATH: Bourne Shell Variables.
-* PIPESTATUS: Bash Variables.
-* PPID: Bash Variables.
-* PROMPT_COMMAND: Bash Variables.
+ (line 42)
+* PIPESTATUS: Bash Variables. (line 354)
+* POSIXLY_CORRECT: Bash Variables. (line 359)
+* PPID: Bash Variables. (line 368)
+* PROMPT_COMMAND: Bash Variables. (line 372)
* PS1: Bourne Shell Variables.
+ (line 48)
* PS2: Bourne Shell Variables.
-* PS3: Bash Variables.
-* PS4: Bash Variables.
-* PWD: Bash Variables.
-* RANDOM: Bash Variables.
-* REPLY: Bash Variables.
-* SECONDS: Bash Variables.
-* SHELLOPTS: Bash Variables.
-* SHLVL: Bash Variables.
+ (line 53)
+* PS3: Bash Variables. (line 376)
+* PS4: Bash Variables. (line 381)
+* PWD: Bash Variables. (line 387)
+* RANDOM: Bash Variables. (line 390)
+* REPLY: Bash Variables. (line 395)
+* SECONDS: Bash Variables. (line 398)
+* SHELL: Bash Variables. (line 404)
+* SHELLOPTS: Bash Variables. (line 409)
+* SHLVL: Bash Variables. (line 418)
* show-all-if-ambiguous: Readline Init File Syntax.
-* TIMEFORMAT: Bash Variables.
-* TMOUT: Bash Variables.
-* UID: Bash Variables.
+ (line 156)
+* show-all-if-unmodified: Readline Init File Syntax.
+ (line 162)
+* TEXTDOMAIN: Locale Translation. (line 11)
+* TEXTDOMAINDIR: Locale Translation. (line 11)
+* TIMEFORMAT: Bash Variables. (line 423)
+* TMOUT: Bash Variables. (line 461)
+* UID: Bash Variables. (line 473)
* visible-stats: Readline Init File Syntax.
+ (line 171)
\1f
File: bashref.info, Node: Function Index, Next: Concept Index, Prev: Variable Index, Up: Top
Function Index
**************
+\0\b[index\0\b]
* Menu:
* abort (C-g): Miscellaneous Commands.
-* accept-line (Newline, Return): Commands For History.
-* backward-char (C-b): Commands For Moving.
-* backward-delete-char (Rubout): Commands For Text.
-* backward-kill-line (C-x Rubout): Commands For Killing.
-* backward-kill-word (M-DEL): Commands For Killing.
-* backward-word (M-b): Commands For Moving.
-* beginning-of-history (M-<): Commands For History.
-* beginning-of-line (C-a): Commands For Moving.
-* call-last-kbd-macro (C-x e): Keyboard Macros.
-* capitalize-word (M-c): Commands For Text.
+ (line 10)
+* accept-line (Newline or Return): Commands For History. (line 6)
+* backward-char (C-b): Commands For Moving. (line 15)
+* backward-delete-char (Rubout): Commands For Text. (line 11)
+* backward-kill-line (C-x Rubout): Commands For Killing. (line 9)
+* backward-kill-word (M-<DEL>): Commands For Killing. (line 24)
+* backward-word (M-b): Commands For Moving. (line 22)
+* beginning-of-history (M-<): Commands For History. (line 20)
+* beginning-of-line (C-a): Commands For Moving. (line 6)
+* call-last-kbd-macro (C-x e): Keyboard Macros. (line 13)
+* capitalize-word (M-c): Commands For Text. (line 46)
* character-search (C-]): Miscellaneous Commands.
+ (line 41)
* character-search-backward (M-C-]): Miscellaneous Commands.
-* clear-screen (C-l): Commands For Moving.
-* complete (TAB): Commands For Completion.
-* copy-backward-word (): Commands For Killing.
-* copy-forward-word (): Commands For Killing.
-* copy-region-as-kill (): Commands For Killing.
-* delete-char (C-d): Commands For Text.
+ (line 46)
+* clear-screen (C-l): Commands For Moving. (line 26)
+* complete (<TAB>): Commands For Completion.
+ (line 6)
+* copy-backward-word (): Commands For Killing. (line 49)
+* copy-forward-word (): Commands For Killing. (line 54)
+* copy-region-as-kill (): Commands For Killing. (line 45)
+* delete-char (C-d): Commands For Text. (line 6)
* delete-char-or-list (): Commands For Completion.
-* delete-horizontal-space (): Commands For Killing.
-* digit-argument (M-0, M-1, ... M--): Numeric Arguments.
+ (line 34)
+* delete-horizontal-space (): Commands For Killing. (line 37)
+* digit-argument (M-0, M-1, ... M--): Numeric Arguments. (line 6)
* do-uppercase-version (M-a, M-b, M-X, ...): Miscellaneous Commands.
-* downcase-word (M-l): Commands For Text.
+ (line 14)
+* downcase-word (M-l): Commands For Text. (line 42)
* dump-functions (): Miscellaneous Commands.
+ (line 64)
* dump-macros (): Miscellaneous Commands.
+ (line 76)
* dump-variables (): Miscellaneous Commands.
-* end-kbd-macro (C-x )): Keyboard Macros.
-* end-of-history (M->): Commands For History.
-* end-of-line (C-e): Commands For Moving.
+ (line 70)
+* end-kbd-macro (C-x )): Keyboard Macros. (line 9)
+* end-of-history (M->): Commands For History. (line 23)
+* end-of-line (C-e): Commands For Moving. (line 9)
* exchange-point-and-mark (C-x C-x): Miscellaneous Commands.
-* forward-backward-delete-char (): Commands For Text.
-* forward-char (C-f): Commands For Moving.
-* forward-search-history (C-s): Commands For History.
-* forward-word (M-f): Commands For Moving.
-* history-search-backward (): Commands For History.
-* history-search-forward (): Commands For History.
+ (line 36)
+* forward-backward-delete-char (): Commands For Text. (line 15)
+* forward-char (C-f): Commands For Moving. (line 12)
+* forward-search-history (C-s): Commands For History. (line 31)
+* forward-word (M-f): Commands For Moving. (line 18)
+* history-search-backward (): Commands For History. (line 51)
+* history-search-forward (): Commands For History. (line 46)
* insert-comment (M-#): Miscellaneous Commands.
+ (line 51)
* insert-completions (M-*): Commands For Completion.
-* kill-line (C-k): Commands For Killing.
-* kill-region (): Commands For Killing.
-* kill-whole-line (): Commands For Killing.
-* kill-word (M-d): Commands For Killing.
+ (line 18)
+* kill-line (C-k): Commands For Killing. (line 6)
+* kill-region (): Commands For Killing. (line 41)
+* kill-whole-line (): Commands For Killing. (line 15)
+* kill-word (M-d): Commands For Killing. (line 19)
* menu-complete (): Commands For Completion.
-* next-history (C-n): Commands For History.
+ (line 22)
+* next-history (C-n): Commands For History. (line 17)
* non-incremental-forward-search-history (M-n): Commands For History.
+ (line 41)
* non-incremental-reverse-search-history (M-p): Commands For History.
+ (line 36)
+* overwrite-mode (): Commands For Text. (line 50)
* possible-completions (M-?): Commands For Completion.
-* prefix-meta (ESC): Miscellaneous Commands.
-* previous-history (C-p): Commands For History.
-* quoted-insert (C-q, C-v): Commands For Text.
+ (line 15)
+* prefix-meta (<ESC>): Miscellaneous Commands.
+ (line 18)
+* previous-history (C-p): Commands For History. (line 13)
+* quoted-insert (C-q or C-v): Commands For Text. (line 20)
* re-read-init-file (C-x C-r): Miscellaneous Commands.
-* redraw-current-line (): Commands For Moving.
-* reverse-search-history (C-r): Commands For History.
+ (line 6)
+* redraw-current-line (): Commands For Moving. (line 30)
+* reverse-search-history (C-r): Commands For History. (line 27)
* revert-line (M-r): Miscellaneous Commands.
-* self-insert (a, b, A, 1, !, ...): Commands For Text.
+ (line 25)
+* self-insert (a, b, A, 1, !, ...): Commands For Text. (line 24)
* set-mark (C-@): Miscellaneous Commands.
-* start-kbd-macro (C-x (): Keyboard Macros.
-* transpose-chars (C-t): Commands For Text.
-* transpose-words (M-t): Commands For Text.
-* undo (C-_, C-x C-u): Miscellaneous Commands.
-* universal-argument (): Numeric Arguments.
-* unix-line-discard (C-u): Commands For Killing.
-* unix-word-rubout (C-w): Commands For Killing.
-* upcase-word (M-u): Commands For Text.
-* yank (C-y): Commands For Killing.
-* yank-last-arg (M-., M-_): Commands For History.
-* yank-nth-arg (M-C-y): Commands For History.
-* yank-pop (M-y): Commands For Killing.
+ (line 32)
+* start-kbd-macro (C-x (): Keyboard Macros. (line 6)
+* transpose-chars (C-t): Commands For Text. (line 27)
+* transpose-words (M-t): Commands For Text. (line 33)
+* undo (C-_ or C-x C-u): Miscellaneous Commands.
+ (line 22)
+* universal-argument (): Numeric Arguments. (line 10)
+* unix-filename-rubout (): Commands For Killing. (line 32)
+* unix-line-discard (C-u): Commands For Killing. (line 12)
+* unix-word-rubout (C-w): Commands For Killing. (line 28)
+* upcase-word (M-u): Commands For Text. (line 38)
+* yank (C-y): Commands For Killing. (line 59)
+* yank-last-arg (M-. or M-_): Commands For History. (line 63)
+* yank-nth-arg (M-C-y): Commands For History. (line 56)
+* yank-pop (M-y): Commands For Killing. (line 62)
\1f
File: bashref.info, Node: Concept Index, Prev: Function Index, Up: Top
Concept Index
*************
+\0\b[index\0\b]
* Menu:
-* alias expansion: Aliases.
-* arithmetic evaluation: Shell Arithmetic.
+* alias expansion: Aliases. (line 6)
+* arithmetic evaluation: Shell Arithmetic. (line 6)
* arithmetic expansion: Arithmetic Expansion.
-* arithmetic, shell: Shell Arithmetic.
-* arrays: Arrays.
-* background: Job Control Basics.
-* Bash configuration: Basic Installation.
-* Bash installation: Basic Installation.
+ (line 6)
+* arithmetic, shell: Shell Arithmetic. (line 6)
+* arrays: Arrays. (line 6)
+* background: Job Control Basics. (line 6)
+* Bash configuration: Basic Installation. (line 6)
+* Bash installation: Basic Installation. (line 6)
* Bourne shell: Basic Shell Features.
-* brace expansion: Brace Expansion.
-* builtin: Definitions.
+ (line 6)
+* brace expansion: Brace Expansion. (line 6)
+* builtin: Definitions. (line 16)
* command editing: Readline Bare Essentials.
+ (line 6)
* command execution: Command Search and Execution.
+ (line 6)
* command expansion: Simple Command Expansion.
+ (line 6)
* command history: Bash History Facilities.
+ (line 6)
* command search: Command Search and Execution.
+ (line 6)
* command substitution: Command Substitution.
-* command timing: Pipelines.
+ (line 6)
+* command timing: Pipelines. (line 8)
+* commands, compound: Compound Commands. (line 6)
* commands, conditional: Conditional Constructs.
-* commands, grouping: Command Grouping.
-* commands, lists: Lists.
-* commands, looping: Looping Constructs.
-* commands, pipelines: Pipelines.
-* commands, shell: Shell Commands.
-* commands, simple: Simple Commands.
-* comments, shell: Comments.
+ (line 6)
+* commands, grouping: Command Grouping. (line 6)
+* commands, lists: Lists. (line 6)
+* commands, looping: Looping Constructs. (line 6)
+* commands, pipelines: Pipelines. (line 6)
+* commands, shell: Shell Commands. (line 6)
+* commands, simple: Simple Commands. (line 6)
+* comments, shell: Comments. (line 6)
* completion builtins: Programmable Completion Builtins.
-* configuration: Basic Installation.
-* control operator: Definitions.
-* directory stack: The Directory Stack.
+ (line 6)
+* configuration: Basic Installation. (line 6)
+* control operator: Definitions. (line 20)
+* directory stack: The Directory Stack. (line 6)
* editing command lines: Readline Bare Essentials.
-* environment: Environment.
-* evaluation, arithmetic: Shell Arithmetic.
-* event designators: Event Designators.
+ (line 6)
+* environment: Environment. (line 6)
+* evaluation, arithmetic: Shell Arithmetic. (line 6)
+* event designators: Event Designators. (line 6)
* execution environment: Command Execution Environment.
-* exit status <1>: Exit Status.
-* exit status: Definitions.
-* expansion: Shell Expansions.
+ (line 6)
+* exit status <1>: Exit Status. (line 6)
+* exit status: Definitions. (line 24)
+* expansion: Shell Expansions. (line 6)
* expansion, arithmetic: Arithmetic Expansion.
-* expansion, brace: Brace Expansion.
-* expansion, filename: Filename Expansion.
+ (line 6)
+* expansion, brace: Brace Expansion. (line 6)
+* expansion, filename: Filename Expansion. (line 9)
* expansion, parameter: Shell Parameter Expansion.
-* expansion, pathname: Filename Expansion.
-* expansion, tilde: Tilde Expansion.
-* expressions, arithmetic: Shell Arithmetic.
+ (line 6)
+* expansion, pathname: Filename Expansion. (line 9)
+* expansion, tilde: Tilde Expansion. (line 6)
+* expressions, arithmetic: Shell Arithmetic. (line 6)
* expressions, conditional: Bash Conditional Expressions.
-* field: Definitions.
-* filename: Definitions.
-* filename expansion: Filename Expansion.
-* foreground: Job Control Basics.
-* functions, shell: Shell Functions.
+ (line 6)
+* FDL, GNU Free Documentation License: GNU Free Documentation License.
+ (line 6)
+* field: Definitions. (line 28)
+* filename: Definitions. (line 33)
+* filename expansion: Filename Expansion. (line 9)
+* foreground: Job Control Basics. (line 6)
+* functions, shell: Shell Functions. (line 6)
* history builtins: Bash History Builtins.
-* history events: Event Designators.
-* history expansion: History Interaction.
+ (line 6)
+* history events: Event Designators. (line 7)
+* history expansion: History Interaction. (line 6)
* history list: Bash History Facilities.
+ (line 6)
* History, how to use: Programmable Completion Builtins.
-* identifier: Definitions.
-* initialization file, readline: Readline Init File.
-* installation: Basic Installation.
+ (line 203)
+* identifier: Definitions. (line 49)
+* initialization file, readline: Readline Init File. (line 6)
+* installation: Basic Installation. (line 6)
* interaction, readline: Readline Interaction.
-* interactive shell <1>: Interactive Shells.
-* interactive shell: Invoking Bash.
-* job: Definitions.
-* job control <1>: Job Control Basics.
-* job control: Definitions.
+ (line 6)
+* interactive shell <1>: Interactive Shells. (line 6)
+* interactive shell: Invoking Bash. (line 128)
+* internationalization: Locale Translation. (line 6)
+* job: Definitions. (line 36)
+* job control <1>: Definitions. (line 40)
+* job control: Job Control Basics. (line 6)
* kill ring: Readline Killing Commands.
+ (line 19)
* killing text: Readline Killing Commands.
-* localization: Locale Translation.
-* matching, pattern: Pattern Matching.
-* metacharacter: Definitions.
-* name: Definitions.
+ (line 6)
+* localization: Locale Translation. (line 6)
+* login shell: Invoking Bash. (line 125)
+* matching, pattern: Pattern Matching. (line 6)
+* metacharacter: Definitions. (line 44)
+* name: Definitions. (line 49)
+* native languages: Locale Translation. (line 6)
* notation, readline: Readline Bare Essentials.
-* operator, shell: Definitions.
+ (line 6)
+* operator, shell: Definitions. (line 55)
* parameter expansion: Shell Parameter Expansion.
-* parameters: Shell Parameters.
+ (line 6)
+* parameters: Shell Parameters. (line 6)
* parameters, positional: Positional Parameters.
-* parameters, special: Special Parameters.
-* pathname expansion: Filename Expansion.
-* pattern matching: Pattern Matching.
-* pipeline: Pipelines.
-* POSIX: Definitions.
-* POSIX Mode: Bash POSIX Mode.
-* process group: Definitions.
-* process group ID: Definitions.
+ (line 6)
+* parameters, special: Special Parameters. (line 6)
+* pathname expansion: Filename Expansion. (line 9)
+* pattern matching: Pattern Matching. (line 6)
+* pipeline: Pipelines. (line 6)
+* POSIX: Definitions. (line 9)
+* POSIX Mode: Bash POSIX Mode. (line 6)
+* process group: Definitions. (line 59)
+* process group ID: Definitions. (line 63)
* process substitution: Process Substitution.
+ (line 6)
* programmable completion: Programmable Completion.
-* prompting: Printing a Prompt.
-* quoting: Quoting.
-* quoting, ANSI: ANSI-C Quoting.
+ (line 6)
+* prompting: Printing a Prompt. (line 6)
+* quoting: Quoting. (line 6)
+* quoting, ANSI: ANSI-C Quoting. (line 6)
* Readline, how to use: Job Control Variables.
-* redirection: Redirections.
-* reserved word: Definitions.
+ (line 24)
+* redirection: Redirections. (line 6)
+* reserved word: Definitions. (line 67)
* restricted shell: The Restricted Shell.
-* return status: Definitions.
-* shell arithmetic: Shell Arithmetic.
-* shell function: Shell Functions.
-* shell script: Shell Scripts.
-* shell variable: Shell Parameters.
-* shell, interactive: Interactive Shells.
-* signal: Definitions.
-* signal handling: Signals.
-* special builtin <1>: Special Builtins.
-* special builtin: Definitions.
-* startup files: Bash Startup Files.
-* suspending jobs: Job Control Basics.
-* tilde expansion: Tilde Expansion.
-* token: Definitions.
-* variable, shell: Shell Parameters.
-* word: Definitions.
-* word splitting: Word Splitting.
+ (line 6)
+* return status: Definitions. (line 72)
+* shell arithmetic: Shell Arithmetic. (line 6)
+* shell function: Shell Functions. (line 6)
+* shell script: Shell Scripts. (line 6)
+* shell variable: Shell Parameters. (line 6)
+* shell, interactive: Interactive Shells. (line 6)
+* signal: Definitions. (line 75)
+* signal handling: Signals. (line 6)
+* special builtin <1>: Definitions. (line 79)
+* special builtin: Special Builtins. (line 6)
+* startup files: Bash Startup Files. (line 6)
+* suspending jobs: Job Control Basics. (line 6)
+* tilde expansion: Tilde Expansion. (line 6)
+* token: Definitions. (line 83)
+* translation, native languages: Locale Translation. (line 6)
+* variable, shell: Shell Parameters. (line 6)
+* variables, readline: Readline Init File Syntax.
+ (line 33)
+* word: Definitions. (line 87)
+* word splitting: Word Splitting. (line 6)
* yanking text: Readline Killing Commands.
+ (line 6)
\1f
Tag Table:
-Node: Top\7f1185
-Node: Introduction\7f3316
-Node: What is Bash?\7f3541
-Node: What is a shell?\7f4642
-Node: Definitions\7f6876
-Node: Basic Shell Features\7f9542
-Node: Shell Syntax\7f10766
-Node: Shell Operation\7f11790
-Node: Quoting\7f13085
-Node: Escape Character\7f14345
-Node: Single Quotes\7f14817
-Node: Double Quotes\7f15152
-Node: ANSI-C Quoting\7f16055
-Node: Locale Translation\7f16957
-Node: Comments\7f17378
-Node: Shell Commands\7f17984
-Node: Simple Commands\7f18865
-Node: Pipelines\7f19488
-Node: Lists\7f21015
-Node: Looping Constructs\7f22529
-Node: Conditional Constructs\7f24976
-Node: Command Grouping\7f30918
-Node: Shell Functions\7f32295
-Node: Shell Parameters\7f34833
-Node: Positional Parameters\7f36159
-Node: Special Parameters\7f37052
-Node: Shell Expansions\7f39711
-Node: Brace Expansion\7f41635
-Node: Tilde Expansion\7f43305
-Node: Shell Parameter Expansion\7f45637
-Node: Command Substitution\7f52439
-Node: Arithmetic Expansion\7f53761
-Node: Process Substitution\7f54606
-Node: Word Splitting\7f55643
-Node: Filename Expansion\7f57095
-Node: Pattern Matching\7f59055
-Node: Quote Removal\7f61450
-Node: Redirections\7f61736
-Node: Executing Commands\7f68607
-Node: Simple Command Expansion\7f69274
-Node: Command Search and Execution\7f71197
-Node: Command Execution Environment\7f73194
-Node: Environment\7f75648
-Node: Exit Status\7f77300
-Node: Signals\7f78497
-Node: Shell Scripts\7f80392
-Node: Shell Builtin Commands\7f82776
-Node: Bourne Shell Builtins\7f84211
-Node: Bash Builtins\7f99107
-Node: The Set Builtin\7f123146
-Node: Special Builtins\7f129959
-Node: Shell Variables\7f130931
-Node: Bourne Shell Variables\7f131367
-Node: Bash Variables\7f133147
-Node: Bash Features\7f147888
-Node: Invoking Bash\7f148770
-Node: Bash Startup Files\7f153441
-Node: Interactive Shells\7f158148
-Node: What is an Interactive Shell?\7f158550
-Node: Is this Shell Interactive?\7f159185
-Node: Interactive Shell Behavior\7f159991
-Node: Bash Conditional Expressions\7f163279
-Node: Shell Arithmetic\7f166574
-Node: Aliases\7f169005
-Node: Arrays\7f171510
-Node: The Directory Stack\7f174530
-Node: Directory Stack Builtins\7f175236
-Node: Printing a Prompt\7f178114
-Node: The Restricted Shell\7f180486
-Node: Bash POSIX Mode\7f181964
-Node: Job Control\7f186258
-Node: Job Control Basics\7f186724
-Node: Job Control Builtins\7f190939
-Node: Job Control Variables\7f195234
-Node: Command Line Editing\7f196384
-Node: Introduction and Notation\7f197382
-Node: Readline Interaction\7f198999
-Node: Readline Bare Essentials\7f200191
-Node: Readline Movement Commands\7f201971
-Node: Readline Killing Commands\7f202927
-Node: Readline Arguments\7f204832
-Node: Searching\7f205806
-Node: Readline Init File\7f207685
-Node: Readline Init File Syntax\7f208739
-Node: Conditional Init Constructs\7f218285
-Node: Sample Init File\7f220723
-Node: Bindable Readline Commands\7f223892
-Node: Commands For Moving\7f225085
-Node: Commands For History\7f225933
-Node: Commands For Text\7f228727
-Node: Commands For Killing\7f230678
-Node: Numeric Arguments\7f232644
-Node: Commands For Completion\7f233770
-Node: Keyboard Macros\7f237602
-Node: Miscellaneous Commands\7f238160
-Node: Readline vi Mode\7f242534
-Node: Programmable Completion\7f243444
-Node: Programmable Completion Builtins\7f248120
-Node: Using History Interactively\7f254226
-Node: Bash History Facilities\7f254905
-Node: Bash History Builtins\7f257466
-Node: History Interaction\7f261038
-Node: Event Designators\7f263590
-Node: Word Designators\7f264517
-Node: Modifiers\7f266146
-Node: Installing Bash\7f267463
-Node: Basic Installation\7f268605
-Node: Compilers and Options\7f271723
-Node: Compiling For Multiple Architectures\7f272457
-Node: Installation Names\7f274114
-Node: Specifying the System Type\7f274837
-Node: Sharing Defaults\7f275544
-Node: Operation Controls\7f276209
-Node: Optional Features\7f277160
-Node: Reporting Bugs\7f284581
-Node: Major Differences From The Bourne Shell\7f285678
-Node: Builtin Index\7f299726
-Node: Reserved Word Index\7f303317
-Node: Variable Index\7f304793
-Node: Function Index\7f310465
-Node: Concept Index\7f314955
+Node: Top\7f1349
+Node: Introduction\7f3485
+Node: What is Bash?\7f3714
+Node: What is a shell?\7f4807
+Node: Definitions\7f7348
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+Node: Double Quotes\7f15741
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+Node: Locale Translation\7f17723
+Node: Comments\7f18619
+Node: Shell Commands\7f19233
+Node: Simple Commands\7f19999
+Node: Pipelines\7f20630
+Node: Lists\7f22505
+Node: Compound Commands\7f24136
+Node: Looping Constructs\7f24920
+Node: Conditional Constructs\7f27367
+Node: Command Grouping\7f34434
+Node: Shell Functions\7f35883
+Node: Shell Parameters\7f40151
+Node: Positional Parameters\7f41732
+Node: Special Parameters\7f42632
+Node: Shell Expansions\7f45299
+Node: Brace Expansion\7f47224
+Node: Tilde Expansion\7f49549
+Node: Shell Parameter Expansion\7f51890
+Node: Command Substitution\7f59153
+Node: Arithmetic Expansion\7f60486
+Node: Process Substitution\7f61336
+Node: Word Splitting\7f62386
+Node: Filename Expansion\7f63847
+Node: Pattern Matching\7f65983
+Node: Quote Removal\7f69316
+Node: Redirections\7f69611
+Node: Executing Commands\7f77190
+Node: Simple Command Expansion\7f77865
+Node: Command Search and Execution\7f79795
+Node: Command Execution Environment\7f81801
+Node: Environment\7f84572
+Node: Exit Status\7f86232
+Node: Signals\7f87436
+Node: Shell Scripts\7f89400
+Node: Shell Builtin Commands\7f91918
+Node: Bourne Shell Builtins\7f93497
+Node: Bash Builtins\7f110450
+Node: The Set Builtin\7f138577
+Node: Special Builtins\7f146800
+Node: Shell Variables\7f147777
+Node: Bourne Shell Variables\7f148217
+Node: Bash Variables\7f150198
+Node: Bash Features\7f169913
+Node: Invoking Bash\7f170796
+Node: Bash Startup Files\7f176615
+Node: Interactive Shells\7f181473
+Node: What is an Interactive Shell?\7f181883
+Node: Is this Shell Interactive?\7f182533
+Node: Interactive Shell Behavior\7f183348
+Node: Bash Conditional Expressions\7f186624
+Node: Shell Arithmetic\7f190049
+Node: Aliases\7f192794
+Node: Arrays\7f195362
+Node: The Directory Stack\7f198393
+Node: Directory Stack Builtins\7f199107
+Node: Printing a Prompt\7f201998
+Node: The Restricted Shell\7f204712
+Node: Bash POSIX Mode\7f206544
+Node: Job Control\7f213197
+Node: Job Control Basics\7f213664
+Node: Job Control Builtins\7f217954
+Node: Job Control Variables\7f222274
+Node: Command Line Editing\7f223432
+Node: Introduction and Notation\7f224431
+Node: Readline Interaction\7f226053
+Node: Readline Bare Essentials\7f227244
+Node: Readline Movement Commands\7f229033
+Node: Readline Killing Commands\7f229998
+Node: Readline Arguments\7f231918
+Node: Searching\7f232962
+Node: Readline Init File\7f235148
+Node: Readline Init File Syntax\7f236207
+Node: Conditional Init Constructs\7f247860
+Node: Sample Init File\7f250393
+Node: Bindable Readline Commands\7f253510
+Node: Commands For Moving\7f254717
+Node: Commands For History\7f255578
+Node: Commands For Text\7f258479
+Node: Commands For Killing\7f261152
+Node: Numeric Arguments\7f263294
+Node: Commands For Completion\7f264433
+Node: Keyboard Macros\7f268026
+Node: Miscellaneous Commands\7f268597
+Node: Readline vi Mode\7f273908
+Node: Programmable Completion\7f274822
+Node: Programmable Completion Builtins\7f280634
+Node: Using History Interactively\7f288004
+Node: Bash History Facilities\7f288684
+Node: Bash History Builtins\7f291379
+Node: History Interaction\7f295236
+Node: Event Designators\7f297792
+Node: Word Designators\7f298807
+Node: Modifiers\7f300446
+Node: Installing Bash\7f301852
+Node: Basic Installation\7f302989
+Node: Compilers and Options\7f305681
+Node: Compiling For Multiple Architectures\7f306422
+Node: Installation Names\7f308086
+Node: Specifying the System Type\7f308904
+Node: Sharing Defaults\7f309620
+Node: Operation Controls\7f310293
+Node: Optional Features\7f311251
+Node: Reporting Bugs\7f319530
+Node: Major Differences From The Bourne Shell\7f320724
+Node: Copying This Manual\7f336496
+Node: GNU Free Documentation License\7f336772
+Node: Builtin Index\7f359178
+Node: Reserved Word Index\7f365727
+Node: Variable Index\7f368163
+Node: Function Index\7f378882
+Node: Concept Index\7f385602
\1f
End Tag Table
projects / platform / upstream / bash.git / blobdiff