-This is bashref.info, produced by makeinfo version 4.1 from
-/usr/homes/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 is bashref.info, produced by makeinfo version 4.11 from
+/Users/chet/src/bash/src/doc/bashref.texi.
This text is a brief description of the features that are present in
-the Bash shell.
+the Bash shell (version 4.0, 28 October 2008).
-This is Edition 2.5b, last updated 15 July 2002,
-of `The GNU Bash Reference Manual',
-for `Bash', Version 2.05b.
+ This is Edition 4.0, last updated 28 October 2008, of `The GNU Bash
+Reference Manual', for `Bash', Version 4.0.
-Copyright (C) 1991-2002 Free Software Foundation, Inc.
+ Copyright (C) 1988-2008 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 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.
+ 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, 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 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.
+ (a) The FSF's Back-Cover Text is: You are free to copy and modify
+ this GNU manual. Buying copies from GNU Press supports the FSF in
+ developing GNU and promoting software freedom."
+
+
+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 2.5b, last updated 15 July 2002, of `The GNU Bash
-Reference Manual', for `Bash', Version 2.05b.
+This text is a brief description of the features that are present in
+the Bash shell (version 4.0, 28 October 2008).
- Copyright (C) 1991-2002 Free Software Foundation, Inc.
+ This is Edition 4.0, last updated 28 October 2008, of `The GNU Bash
+Reference Manual', for `Bash', Version 4.0.
Bash contains features that appear in other popular shells, and some
features that only appear in Bash. Some of the shells that Bash has
* Menu:
* Introduction:: An introduction to the shell.
-
* Definitions:: Some definitions used in the rest of this
manual.
-
* Basic Shell Features:: The shell "building blocks".
-
* Shell Builtin Commands:: Commands that are a part of the shell.
-
* Shell Variables:: Variables used or set by Bash.
-
* Bash Features:: Features found only in Bash.
-
-* Job Control:: A chapter describing what job control is
- and how Bash allows you to use it.
-
-* Using History Interactively:: Chapter dealing with history expansion
- rules.
-
+* Job Control:: What job control is and how Bash allows you
+ to use it.
* Command Line Editing:: Chapter describing the command line
editing features.
-
+* Using History Interactively:: Command History Expansion
* Installing Bash:: How to build and install Bash on your system.
-
* Reporting Bugs:: How to report bugs in Bash.
-
* Major Differences From The Bourne Shell:: A terse list of the differences
between Bash and historical
versions of /bin/sh.
-
-* Builtin Index:: Index of Bash builtin commands.
-
-* Reserved Word Index:: Index of Bash reserved words.
-
-* Variable Index:: Quick reference helps you find the
- variable you want.
-
-* Function Index:: Index of bindable Readline functions.
-
-* Concept Index:: General index for concepts described in
- this manual.
+* GNU Free Documentation License:: Copying and sharing this documentation.
+* Indexes:: Various indexes for this manual.
\1f
File: bashref.info, Node: Introduction, Next: Definitions, Prev: Top, Up: Top
-Introduction
-************
+1 Introduction
+**************
* Menu:
* What is Bash?:: A short description of Bash.
-
* What is a shell?:: A brief introduction to shells.
\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
intended to be a conformant implementation of the IEEE POSIX Shell and
-Tools specification (IEEE Working Group 1003.2). It offers functional
-improvements over `sh' for both interactive and programming use.
+Tools portion of the IEEE POSIX specification (IEEE Standard 1003.1).
+It offers functional improvements over `sh' for both interactive and
+programming use.
While the GNU operating system provides other shells, including a
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. The term macro processor means functionality where text and
+symbols are expanded to create larger expressions.
- 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
+ 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 utilities 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
- concerned with POSIX 1003.2, the Shell and Tools Standard.
+ primarily concerned with the Shell and Utilities portion of the
+ POSIX 1003.1 standard.
`blank'
A space or tab character.
rather than by an executable program somewhere in the file system.
`control operator'
- A `word' that performs a control function. It is a `newline' or
- one of the following: `||', `&&', `&', `;', `;;', `|', `(', or `)'.
+ A `token' that performs a control function. It is a `newline' or
+ one of the following: `||', `&&', `&', `;', `;;', `|', `|&', `(',
+ or `)'.
`exit status'
The value returned by a command to its caller. The value is
`operator'
A `control operator' or a `redirection operator'. *Note
- Redirections::, for a list of redirection operators.
+ Redirections::, for a list of redirection operators. Operators
+ contain at least one unquoted `metacharacter'.
`process group'
A collection of related processes each having the same process
group ID.
`process group ID'
- A unique identifer that represents a `process group' during its
+ A unique identifier that represents a `process group' during its
lifetime.
`reserved word'
`special builtin'
A shell builtin command that has been classified as special by the
- POSIX 1003.2 standard.
+ POSIX standard.
`token'
A sequence of characters considered a single unit by the shell.
It is either a `word' or an `operator'.
`word'
- A `token' that is not an `operator'.
+ A sequence of characters treated as a unit by the shell. Words
+ may not include unquoted `metacharacters'.
\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:
* Shell Operation:: The basic operation of the shell.
-
* Quoting:: How to remove the special meaning from characters.
-
* Comments:: How to specify comments.
When the shell reads input, it proceeds through a sequence of
\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
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
+ rules described in *note Quoting::. These tokens are separated by
`metacharacters'. Alias expansion is performed by this step
(*note Aliases::).
\1f
File: bashref.info, Node: Quoting, Next: Comments, Prev: Shell Operation, Up: Shell Syntax
-Quoting
--------
+3.1.2 Quoting
+-------------
* Menu:
* Double Quotes:: How to suppress most of the interpretation of a
sequence of characters.
* ANSI-C Quoting:: How to expand ANSI-C sequences in quoted strings.
-
* Locale Translation:: How to translate strings into different languages.
Quoting is used to remove the special meaning of certain characters
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.
+When the command history expansion facilities are being used (*note
+History Interaction::), 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.
\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
-characters: `$', ``', `"', `\', or `newline'. Within double quotes,
-backslashes that are followed by one of these characters are removed.
-Backslashes preceding characters without a special meaning are left
-unmodified. A double quote may be quoted within double quotes by
-preceding it with a backslash.
+Enclosing characters in double quotes (`"') preserves the literal value
+of all characters within the quotes, with the exception of `$', ``',
+`\', and, when history expansion is enabled, `!'. 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. If
+enabled, history expansion will be performed unless an `!' appearing in
+double quotes is escaped using a backslash. The backslash preceding
+the `!' is not removed.
The special parameters `*' and `@' have special meaning when in
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 `$'STRING'' are treated specially. The word
-expands to STRING, with backslash-escaped characters replaced as
-specified by the ANSI C standard. Backslash escape sequences, if
-present, are decoded as follows:
+Words of the form `$'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)
\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.
\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
-remaining characters on that line to be ignored. An interactive shell
-without the `interactive_comments' option enabled does not allow
+The Shopt Builtin::), 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
interactive shells. *Note Interactive Shells::, for a description of
what makes a shell interactive.
\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.
+* Coprocesses:: Two-way communication between commands.
\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
+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.
\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 one of the
+control operators `|' or `|&'.
The format for a pipeline is
- [`time' [`-p']] [`!'] COMMAND1 [`|' COMMAND2 ...]
+ [`time' [`-p']] [`!'] COMMAND1 [ [`|' or `|&'] COMMAND2 ...]
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.
+previous command's output. This connection is performed before any
+redirections specified by the command.
+
+ If `|&' is used, the standard error of COMMAND1 is connected to
+COMMAND2's standard input through the pipe; it is shorthand for `2>&1
+|'. This implicit redirection of the standard error is performed after
+any redirections specified by the command.
The reserved word `time' causes timing statistics to be printed for
the pipeline once it finishes. The statistics currently consist of
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.
+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.
waits for each command to terminate in turn. The return status is the
exit status of the last command executed.
- The control operators `&&' and `||' denote AND lists and OR lists,
-respectively. An AND list has the form
+ AND and OR lists are sequences of one or more pipelines separated by
+the control operators `&&' and `||', respectively. AND and OR lists
+are executed with left associativity.
+
+ An AND list has the form
COMMAND1 && COMMAND2
COMMAND2 is executed if, and only if, COMMAND1 returns an exit status
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, Next: Coprocesses, 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.
command in LIST that is executed, or false if any of the
expressions is invalid.
+
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:
`case WORD in [ [(] PATTERN [| PATTERN]...) COMMAND-LIST ;;]... esac'
`case' will selectively execute the COMMAND-LIST corresponding to
- the first PATTERN that matches WORD. The `|' is used to separate
+ the first PATTERN that matches WORD. If the shell option
+ `nocasematch' (see the description of `shopt' in *note The Shopt
+ Builtin::) is enabled, the match is performed without regard to
+ the case of alphabetic characters. The `|' is used to separate
multiple patterns, and the `)' operator terminates a pattern list.
A list of patterns and an associated command-list is known as a
- CLAUSE. Each clause must be terminated with `;;'. The WORD
- undergoes tilde expansion, parameter expansion, command
+ CLAUSE.
+
+ Each clause must be terminated with `;;', `,&', or `;;&'. The
+ WORD undergoes tilde expansion, parameter expansion, command
substitution, arithmetic expansion, and quote removal before
matching is attempted. Each PATTERN undergoes tilde expansion,
parameter expansion, command substitution, and arithmetic
expansion.
There may be an arbitrary number of `case' clauses, each terminated
- by a `;;'. The first pattern that matches determines the
- command-list that is executed.
+ by a `;;', `;&', or `;;&'. The first pattern that matches
+ determines the command-list that is executed.
Here is an example using `case' in a script that could be used to
describe one interesting feature of an animal:
esac
echo " legs."
+ If the `;;' operator is used, no subsequent matches are attempted
+ after the first pattern match. Using `;&' in place of `;;'
+ causes execution to continue with the COMMAND-LIST associated with
+ the next clause, if any. Using `;;&' in place of `;;' causes the
+ shell to test the patterns in the next clause, if any, and execute
+ any associated COMMAND-LIST on a successful match.
+
The return status is zero if no PATTERN is matched. Otherwise, the
return status is the exit status of the COMMAND-LIST executed.
items. The set of expanded words is printed on the standard error
output stream, each preceded by a number. If the `in WORDS' is
omitted, the positional parameters are printed, as if `in "$@"'
- had been specifed. The `PS3' prompt is then displayed and a line
+ had been specified. The `PS3' prompt is then displayed and a line
is read from the standard input. If the line consists of a number
corresponding to one of the displayed words, then the value of
NAME is set to that word. If the line is empty, the words and
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.
`[[...]]'
Return a status of 0 or 1 depending on the evaluation of the
conditional expression EXPRESSION. Expressions are composed of
- the primaries described below in *Note Bash Conditional
+ the primaries described below in *note Bash Conditional
Expressions::. Word splitting and filename expansion are not
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
- the rules described below in *Note Pattern Matching::. The return
- value is 0 if the string matches or does not match the pattern,
- respectively, and 1 otherwise. Any part of the pattern may be
- quoted to force it to be matched as a string.
+ the rules described below in *note Pattern Matching::. If the
+ shell option `nocasematch' (see the description of `shopt' in
+ *note The Shopt Builtin::) is enabled, the match is performed
+ without regard to the case of alphabetic characters. The return
+ value is 0 if the string matches (`==') or does not match
+ (`!=')the pattern, 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 `nocasematch'
+ (see the description of `shopt' in *note The Shopt Builtin::) is
+ enabled, the match is performed without regard to the case of
+ alphabetic characters. Any part of the pattern may be quoted to
+ force it to be matched as a string. 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.
+
\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; }
In addition to the creation of a subshell, there is a subtle
difference between these two constructs due to historical reasons. The
braces are `reserved words', so they must be separated from the LIST by
-`blank's. The parentheses are `operators', and are recognized as
-separate tokens by the shell even if they are not separated from the
-LIST by whitespace.
+`blank's or other shell metacharacters. The parentheses are
+`operators', and are recognized as separate tokens by the shell even if
+they are not separated from the LIST by whitespace.
The exit status of both of these constructs is the exit status of
LIST.
\1f
+File: bashref.info, Node: Coprocesses, Prev: Compound Commands, Up: Shell Commands
+
+3.2.5 Coprocesses
+-----------------
+
+A `coprocess' is a shell command preceded by the `coproc' reserved word.
+A coprocess is executed asynchronously in a subshell, as if the command
+had been terminated with the `&' control operator, with a two-way pipe
+established between the executing shell and the coprocess.
+
+ The format for a coprocess is:
+ `coproc' [NAME] COMMAND [REDIRECTIONS]
+
+This creates a coprocess named NAME. If NAME is not supplied, the
+default name is COPROC.
+
+ When the coproc is executed, the shell creates an array variable
+(*note Arrays::) named NAME in the context of the executing shell. The
+standard output of COMMAND is connected via a pipe to a file descriptor
+in the executing shell, and that file descriptor is assigned to NAME[0].
+The standard input of COMMAND is connected via a pipe to a file
+descriptor in the executing shell, and that file descriptor is assigned
+to NAME[1]. This pipe is established before any redirections specified
+by the command (*note Redirections::). The file descriptors can be
+utilized as arguments to shell commands and redirections using standard
+word expansions.
+
+ The process id of the shell spawned to execute the coprocess is
+available as the value of the variable NAME_PID. The `wait' builtin
+command may be used to wait for the coprocess to terminate.
+
+ The return status of a coprocess is the exit status of COMMAND.
+
+\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.
+
+ A function definition may be deleted using the `-f' option to the
+`unset' builtin (*note Bourne Shell Builtins::).
+
+ 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
+from the command list by whitespace or another shell metacharacter.
+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.
+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' and `RETURN' traps are 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' and `RETURN' traps). *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 function'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'. 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::).
+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, 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 `"$@"' as explained below. Filename expansion is
-not performed. Assignment statements may also appear as arguments to
-the `declare', `typeset', `export', `readonly', and `local' builtin
-commands.
+evaluated as an arithmetic expression even if the `$((...))' 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.
+
+ In the context where an assignment statement is assigning a value to
+a shell variable or array index (*note Arrays::), the `+=' operator can
+be used to append to or add to the variable's previous value. When
+`+=' is applied to a variable for which the integer attribute has been
+set, VALUE is evaluated as an arithmetic expression and added to the
+variable's current value, which is also evaluated. When `+=' is
+applied to an array variable using compound assignment (*note
+Arrays::), the variable's value is not unset (as it is when using `='),
+and new values are appended to the array beginning at one greater than
+the array's maximum index (for indexed arrays), or added as additional
+key-value pairs in an associative array. When applied to a
+string-valued variable, VALUE is expanded and appended to the
+variable's value.
\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
\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.
`*'
Expands to the positional parameters, starting from one. When the
expansion occurs within double quotes, each parameter expands to a
separate word. That is, `"$@"' is equivalent to `"$1" "$2" ...'.
- When there are no positional parameters, `"$@"' and `$@' expand to
- nothing (i.e., they are removed).
+ If the double-quoted expansion occurs within a word, the expansion
+ of the first parameter is joined with the beginning part of the
+ original word, and the expansion of the last parameter is joined
+ with the last part of the original word. When there are no
+ positional parameters, `"$@"' and `$@' expand to nothing (i.e.,
+ they are removed).
`#'
Expands to the number of positional parameters in decimal.
invoke Bash, as given by argument zero.
`_'
- (An underscore.) At shell startup, set to the absolute filename
- of the shell or shell script being executed as passed in the
- argument list. Subsequently, expands to the last argument to the
- previous command, after expansion. Also set to the full pathname
- of each command executed and placed in the environment exported to
- that command. When checking mail, this parameter holds the name
- of the mail file.
+ (An underscore.) At shell startup, set to the absolute pathname
+ used to invoke the shell or shell script being executed as passed
+ in the environment or argument list. Subsequently, expands to the
+ last argument to the previous command, after expansion. Also set
+ to the full pathname used to invoke each command executed and
+ placed in the environment exported to that command. When checking
+ mail, this parameter holds the name of the mail file.
\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
\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.
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 seqeunce
+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[INCR]}', where X and Y
+are either integers or single characters, and INCR, an optional
+increment, is an integer. When integers are supplied, the expression
+expands to each number between X and Y, inclusive. Supplied integers
+may be prefixed with `0' to force each term to have the same width.
+When either X or Y begins with a zero, the shell attempts to force all
+generated terms to contain the same number of digits, zero-padding
+where necessary. 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. When the increment is
+supplied, it is used as the difference between each term. The default
+increment is 1 or -1 as appropriate.
+
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 `${' is not considered eligible for
+brace expansion.
This construct is typically used as shorthand when the common prefix
of the strings to be generated is longer than in the above example:
\1f
File: bashref.info, Node: Tilde Expansion, Next: Shell Parameter Expansion, Prev: Brace Expansion, Up: Shell Expansions
-Tilde Expansion
----------------
+3.5.2 Tilde Expansion
+---------------------
- If a word begins with an unquoted tilde character (`~'), all of the
+If a word begins with an unquoted tilde character (`~'), all of the
characters up to the first unquoted slash (or all characters, if there
is no unquoted slash) are considered a TILDE-PREFIX. If none of the
characters in the tilde-prefix are quoted, the characters in the
is left unchanged.
Each variable assignment is checked for unquoted tilde-prefixes
-immediately following a `:' or `='. In these cases, tilde expansion is
-also performed. Consequently, one may use file names with tildes in
-assignments to `PATH', `MAILPATH', and `CDPATH', and the shell assigns
-the expanded value.
+immediately following a `:' or the first `='. In these cases, tilde
+expansion is also performed. Consequently, one may use file names with
+tildes in assignments to `PATH', `MAILPATH', and `CDPATH', and the
+shell assigns the expanded value.
The following table shows how Bash treats unquoted tilde-prefixes:
`~-N'
The string that would be displayed by `dirs -N'
+
\1f
File: bashref.info, Node: Shell Parameter Expansion, Next: Command Substitution, Prev: Tilde Expansion, Up: Shell Expansions
-Shell Parameter Expansion
--------------------------
+3.5.3 Shell Parameter Expansion
+-------------------------------
- The `$' 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.
`${PARAMETER:?WORD}'
If PARAMETER is null or unset, the expansion of WORD (or a message
If OFFSET evaluates to a number less than zero, the value is used
as an offset from the end of the value of PARAMETER. If PARAMETER
is `@', the result is LENGTH positional parameters beginning at
- OFFSET. If PARAMETER is an array name indexed by `@' or `*', the
- result is the LENGTH members of the array beginning with
- `${PARAMETER[OFFSET]}'. Substring indexing is zero-based unless
- the positional parameters are used, in which case the indexing
- starts at 1.
+ OFFSET. If PARAMETER is an indexed array name subscripted by `@'
+ or `*', the result is the LENGTH members of the array beginning
+ with `${PARAMETER[OFFSET]}'. A negative OFFSET is taken relative
+ to one greater than the maximum index of the specified array.
+ Substring expansion applied to an associative array produces
+ undefined results.
+
+ Note that a negative offset must be separated from the colon by at
+ least one space to avoid being confused with the `:-' expansion.
+ Substring indexing is zero-based unless the positional parameters
+ are used, in which case the indexing starts at 1 by default. If
+ OFFSET is 0, and the positional parameters are used, `$@' is
+ prefixed to the list.
`${!PREFIX*}'
+`${!PREFIX@}'
Expands to the names of variables whose names begin with PREFIX,
separated by the first character of the `IFS' special variable.
+ When `@' is used and the expansion appears within double quotes,
+ each variable name expands to a separate word.
+
+`${!NAME[@]}'
+`${!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.
`${#PARAMETER}'
The length in characters of the expanded value of PARAMETER is
list.
`${PARAMETER/PATTERN/STRING}'
-`${PARAMETER//PATTERN/STRING}'
The PATTERN is expanded to produce a pattern just as in filename
expansion. PARAMETER is expanded and the longest match of PATTERN
- against its value is replaced with STRING. In the first form,
- only the first match is replaced. The second form causes all
- matches of PATTERN to be replaced with STRING. If PATTERN begins
- with `#', it must match at the beginning of the expanded value of
- PARAMETER. If PATTERN begins with `%', it must match at the end
- of the expanded value of PARAMETER. If STRING is null, matches of
+ against its value is replaced with STRING. If PATTERN begins with
+ `/', all matches of PATTERN are replaced with STRING. Normally
+ only the first match is replaced. If PATTERN begins with `#', it
+ must match at the beginning of the expanded value of PARAMETER.
+ If PATTERN begins with `%', it must match at the end of the
+ expanded value of PARAMETER. If STRING is null, matches of
PATTERN are deleted and the `/' following PATTERN may be omitted.
If PARAMETER is `@' or `*', the substitution operation is applied
to each positional parameter in turn, and the expansion is the
member of the array in turn, and the expansion is the resultant
list.
+`${PARAMETER^PATTERN}'
+`${PARAMETER^^PATTERN}'
+`${PARAMETER,PATTERN}'
+`${PARAMETER,,PATTERN}'
+ This expansion modifies the case of alphabetic characters in
+ PARAMETER. The PATTERN is expanded to produce a pattern just as in
+ pathname expansion. The `^' operator converts lowercase letters
+ matching PATTERN to uppercase; the `,' operator converts matching
+ uppercase letters to lowercase. The `^^' and `,,' expansions
+ convert each matched character in the expanded value; the `^' and
+ `,' expansions match and convert only the first character. If
+ PATTERN is omitted, it is treated like a `?', which matches every
+ character. If PARAMETER is `@' or `*', the case modification
+ operation is applied to each positional parameter in turn, and the
+ expansion is the resultant list. If PARAMETER is an array
+ variable subscripted with `@' or `*', the case modification
+ operation is applied to each 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
\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.
The shell treats each character of `$IFS' as a delimiter, and splits
the results of the other expansions into words on these characters. If
`IFS' is unset, or its value is exactly `<space><tab><newline>', the
-default, then any sequence of `IFS' characters serves to delimit words.
-If `IFS' has a value other than the default, then sequences of the
-whitespace characters `space' and `tab' are ignored at the beginning
-and end of the word, as long as the whitespace character is in the
-value of `IFS' (an `IFS' whitespace character). Any character in `IFS'
-that is not `IFS' whitespace, along with any adjacent `IFS' whitespace
-characters, delimits a field. A sequence of `IFS' whitespace
-characters is also treated as a delimiter. If the value of `IFS' is
-null, no word splitting occurs.
+default, then sequences of ` <space>', `<tab>', and `<newline>' at the
+beginning and end of the results of the previous expansions are
+ignored, and any sequence of `IFS' characters not at the beginning or
+end serves to delimit words. If `IFS' has a value other than the
+default, then sequences of the whitespace characters `space' and `tab'
+are ignored at the beginning and end of the word, as long as the
+whitespace character is in the value of `IFS' (an `IFS' whitespace
+character). Any character in `IFS' that is not `IFS' whitespace, along
+with any adjacent `IFS' whitespace characters, delimits a field. A
+sequence of `IFS' whitespace characters is also treated as a delimiter.
+If the value of `IFS' is null, no word splitting occurs.
Explicit null arguments (`""' or `''') are retained. Unquoted
implicit null arguments, resulting from the expansion of parameters
\1f
File: bashref.info, Node: Filename Expansion, Next: Quote Removal, Prev: Word Splitting, Up: Shell Expansions
-Filename Expansion
-------------------
+3.5.8 Filename Expansion
+------------------------
* Menu:
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
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.
+ See the description of `shopt' in *note The Shopt Builtin::, for a
+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.
+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 string, including the null string.
+ Matches any string, including the null string. When the
+ `globstar' shell option is enabled, and `*' is used in a filename
+ expansion context, two adjacent `*'s used as a single pattern will
+ match all files and zero or more directories and subdirectories.
+ If followed by a `/', two adjacent `*'s will match only
+ directories and subdirectories.
`?'
Matches any single character.
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:
+ defined in the POSIX standard:
alnum alpha ascii blank cntrl digit graph lower
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 `_'.
Matches one or more occurrences of the given patterns.
`@(PATTERN-LIST)'
- Matches exactly one of the given patterns.
+ Matches one of the given patterns.
`!(PATTERN-LIST)'
Matches anything except one of the given patterns.
\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:
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
------------------
+ Redirections using file descriptors greater than 9 should be used
+with care, as they may conflict with file descriptors the shell uses
+internally.
+
+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
-Redirecting Output
-------------------
+3.6.2 Redirecting Output
+------------------------
- Redirection of output causes the file whose name results from the
+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
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.
The general format for appending output is:
[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
-standard error output (file descriptor 2) to be redirected to the file
-whose name is the expansion of WORD with this construct.
+This construct 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.
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 Appending Standard Output and Standard Error
+--------------------------------------------------
+
+This construct allows both the standard output (file descriptor 1) and
+the standard error output (file descriptor 2) to be appended to the
+file whose name is the expansion of WORD.
- This type of redirection instructs the shell to read input from the
+ The format for appending standard output and standard error is:
+ &>>WORD
+ This is semantically equivalent to
+ >>WORD 2>&1
+
+3.6.6 Here Documents
+--------------------
+
+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.
DELIMITER. This allows here-documents within shell scripts to be
indented in a natural fashion.
-Here Strings
-------------
+3.6.7 Here Strings
+------------------
- A variant of here documents, the format is:
+A variant of here documents, the format is:
<<< WORD
The WORD is expanded and supplied to the command on its standard
input.
-Duplicating File Descriptors
-----------------------------
+3.6.8 Duplicating File Descriptors
+----------------------------------
- The redirection operator
+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
+ 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.
The operator
[N]>&WORD
-
-is used similarly to duplicate output file descriptors. If N is not
+ 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.
-Moving File Descriptors
------------------------
+3.6.9 Moving File Descriptors
+-----------------------------
- The redirection operator
+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.
+ 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.
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.
-moves the file descriptor DIGIT to file descriptor N, or the standard
-output (file descriptor 1) if N is not specified.
-
-Opening File Descriptors for Reading and Writing
-------------------------------------------------
+3.6.10 Opening File Descriptors for Reading and Writing
+-------------------------------------------------------
- The redirection operator
+The redirection operator
[N]<>WORD
-
-causes the file whose name is the expansion of WORD to be opened for
+ 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:
* Simple Command Expansion:: How Bash expands simple commands before
executing them.
-
* Command Search and Execution:: How Bash finds commands and runs them.
-
* Command Execution Environment:: The environment in which Bash
executes commands that are not
shell builtins.
-
* Environment:: The environment given to a command.
-
* Exit Status:: The status returned by commands and how Bash
interprets it.
-
* Signals:: What happens when Bash or a command it runs
receives a signal.
\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
\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.
1. If the command name contains no slashes, the shell attempts to
locate it. If there exists a shell function by that name, that
- function is invoked as described in *Note Shell Functions::.
+ function is invoked as described in *note Shell Functions::.
2. If the name does not match a function, the shell searches for it
in the list of shell builtins. If a match is found, that builtin
directory containing an executable file by that name. Bash uses a
hash table to remember the full pathnames of executable files to
avoid multiple `PATH' searches (see the description of `hash' in
- *Note Bourne Shell Builtins::). A full search of the directories
+ *note Bourne Shell Builtins::). A full search of the directories
in `$PATH' is performed only if the command is not found in the
- hash table. If the search is unsuccessful, the shell prints an
- error message and returns an exit status of 127.
+ hash table. If the search is unsuccessful, the shell searches for
+ a defined shell function named `command_not_found_handle'. If
+ that function exists, it is invoked with the original command and
+ the original command's arguments as its arguments, and the
+ function's exit status becomes the exit status of the shell. If
+ that function is not defined, the shell prints an error message
+ and returns an exit status of 127.
4. If the search is successful, or if the command name contains one
or more slashes, the shell executes the named program in a
5. If this execution fails because the file is not in executable
format, and the file is not a directory, it is assumed to be a
- SHELL SCRIPT and the shell executes it as described in *Note Shell
+ SHELL SCRIPT and the shell executes it as described in *note Shell
Scripts::.
6. If the command was not begun asynchronously, the shell waits for
\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 at invocation (either by default or with
command-line arguments) or by `set'
- * options enabled by `shopt'
+ * options enabled by `shopt' (*note The Shopt Builtin::)
* shell aliases defined with `alias' (*note Aliases::)
* 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'.
\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'.
The environment for any simple command or function may be augmented
temporarily by prefixing it with parameter assignments, as described in
-*Note Shell Parameters::. These assignment statements affect only the
+*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
\1f
File: bashref.info, Node: Exit Status, Next: Signals, Prev: Environment, Up: Executing Commands
-Exit Status
------------
+3.7.5 Exit Status
+-----------------
+
+The exit status of an executed command is the value returned by the
+WAITPID system call or equivalent function. Exit statuses fall between
+0 and 255, though, as explained below, the shell may use values above
+125 specially. Exit statuses from shell builtins and compound commands
+are also limited to this range. Under certain circumstances, the shell
+will use special values to indicate specific failure modes.
For the shell's purposes, a command which exits with a zero exit
status has succeeded. A non-zero exit status indicates failure. This
\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
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, an interactive shell resends the `SIGHUP' to all jobs, running
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.
+The Shopt Builtin::), 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
+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. The shell first searches
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
reinitializes itself, so that the effect is as if a new shell had been
invoked to interpret the script, with the exception that the locations
of commands remembered by the parent (see the description of `hash' in
-*Note Bourne Shell Builtins::) are retained by the child.
+*note Bourne Shell Builtins::) are retained by the child.
Most versions of Unix make this a part of the operating system's
command execution mechanism. If the first line of a script begins with
\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:
* Bourne Shell Builtins:: Builtin commands inherited from the Bourne
Shell.
* Bash Builtins:: Table of builtins specific to Bash.
-* The Set Builtin:: This builtin is so overloaded it
- deserves its own section.
+* Modifying Shell Behavior:: Builtins to modify shell attributes and
+ optional behavior.
* Special Builtins:: Builtin commands classified specially by
- POSIX.2.
+ POSIX.
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
implement functionality impossible or inconvenient to obtain with
separate utilities.
- This section briefly the builtins which Bash inherits from the
-Bourne Shell, as well as the builtin commands which are unique to or
-have been extended in Bash.
+ This section briefly describes the builtins which Bash inherits from
+the Bourne Shell, as well as the builtin commands which are unique to
+or have been extended in Bash.
Several builtin commands are described in other chapters: builtin
commands which provide the Bash interface to the job control facilities
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.
+For example, the `:', `true', `false', and `test' builtins do not
+accept 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
-Shell. These commands are implemented as specified by the POSIX 1003.2
+The following shell builtin commands are inherited from the Bourne
+Shell. These commands are implemented as specified by the POSIX
standard.
`: (a colon)'
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]
exec [-cl] [-a NAME] [COMMAND [ARGUMENTS]]
If COMMAND is supplied, it replaces the shell without creating a
new process. If the `-l' option is supplied, the shell places a
- dash at the beginning of the zeroth arg passed to COMMAND. This
- is what the `login' program does. The `-c' option causes COMMAND
- to be executed with an empty environment. If `-a' is supplied,
- the shell passes NAME as the zeroth argument to COMMAND. If no
- COMMAND is specified, redirections may be used to affect the
+ dash at the beginning of the zeroth argument passed to COMMAND.
+ This is what the `login' program does. The `-c' option causes
+ COMMAND to be executed with an empty environment. If `-a' is
+ supplied, the shell passes NAME as the zeroth argument to COMMAND.
+ If no COMMAND is specified, redirections may be used to affect the
current shell environment. If there are no redirection errors, the
return status is zero; otherwise the return status is non-zero.
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] [-dt] [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
current directory or an invalid option is supplied.
`readonly'
- readonly [-apf] [NAME] ...
+ readonly [-aApf] [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.
+ NAME refers to an indexed array variable; the `-A' option means
+ each NAME refers to an associative 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. 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 non-zero 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]
Shift the positional parameters to the left by N. The positional
- parameters from N+1 ... `$#' are renamed to `$1' ... `$#'-N+1.
- Parameters represented by the numbers `$#' to N+1 are unset. N
- must be a non-negative number less than or equal to `$#'. If N is
- zero or greater than `$#', the positional parameters are not
+ parameters from N+1 ... `$#' are renamed to `$1' ... `$#'-N.
+ Parameters represented by the numbers `$#' to `$#'-N+1 are unset.
+ N must be a non-negative number less than or equal to `$#'. If N
+ is zero or greater than `$#', the positional parameters are not
changed. If N is not supplied, it is assumed to be 1. The return
status is zero unless N is greater than `$#' or less than zero,
non-zero otherwise.
`['
Evaluate a conditional expression EXPR. Each operator and operand
must be a separate argument. Expressions are composed of the
- primaries described below in *Note Bash Conditional Expressions::.
+ primaries described below in *note Bash Conditional Expressions::.
+ `test' does not accept any options, nor does it accept and ignore
+ an argument of `--' as signifying the end of options.
When the `[' form is used, the last argument to the command must
be a `]'.
Expressions may be combined using the following operators, listed
- in decreasing order of precedence.
+ in decreasing order of precedence. The evaluation depends on the
+ number of arguments; see below.
`! EXPR'
True if EXPR is false.
If the second argument is one of the binary conditional
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
- using the second and third arguments. If the first argument
- is exactly `(' and the third argument is exactly `)', the
- result is the one-argument test of the second argument.
- Otherwise, the expression is false. The `-a' and `-o'
- operators are considered binary operators in this case.
+ first and third arguments as operands. The `-a' and `-o'
+ operators are considered binary operators when there are
+ three arguments. If the first argument is `!', the value is
+ the negation of the two-argument test using the second and
+ third arguments. If the first argument is exactly `(' and
+ the third argument is exactly `)', the result is the
+ one-argument test of the second argument. Otherwise, the
+ expression is false.
4 arguments
If the first argument is `!', the result is the negation of
`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. If a SIGSPEC is `ERR', the
- command ARG is executed whenever a simple command has a non-zero
- exit status. The `ERR' trap is not executed if the failed command
- 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 `!'. 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 The Shopt Builtin::) 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 command executed in 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
- process when it is created.
+ Trapped signals that are not being ignored are reset to their
+ original values in a child process when it is created.
The return status is zero unless a SIGSPEC does not specify a
valid signal.
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
+File: bashref.info, Node: Bash Builtins, Next: Modifying Shell Behavior, 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.
+POSIX standard.
`alias'
alias [`-p'] [NAME[=VALUE] ...]
of aliases on the standard output in a form that allows them to be
reused as input. If arguments are supplied, an alias is defined
for each NAME whose VALUE is given. If no VALUE is given, the name
- and value of the alias is printed. Aliases are described in *Note
+ and value of the alias is printed. Aliases are described in *note
Aliases::.
`bind'
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
+ command as it would appear in 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:
+ `"\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
`-x KEYSEQ:SHELL-COMMAND'
Cause SHELL-COMMAND to be executed whenever KEYSEQ is entered.
+ When SHELL-COMMAND is executed, the shell sets the
+ `READLINE_LINE' variable to the contents of the Readline line
+ buffer and the `READLINE_POINT' variable to the current
+ location of the insertion point. If the executed command
+ changes the value of `READLINE_LINE' or `READLINE_POINT',
+ those new values will be reflected in the editing state.
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
non-zero if not.
`declare'
- declare [-afFirtx] [-p] [NAME[=VALUE]]
+ declare [-aAfFilrtux] [-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:
+ NAME. When `-p' is used with NAME arguments, additional options
+ are ignored.
+
+ When `-p' is supplied without NAME arguments, `declare' will
+ display the attributes and values of all variables having the
+ attributes specified by the additional options. If no other
+ options are supplied with `-p', `declare' will display the
+ attributes and values of all shell variables. The `-f' option
+ will restrict the display to shell functions.
+
+ The `-F' option inhibits the display of function definitions; only
+ the function name and attributes are printed. If the `extdebug'
+ shell option is enabled using `shopt' (*note The Shopt Builtin::),
+ 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 indexed array variable (*note Arrays::).
+
+ `-A'
+ Each NAME is an associative array variable (*note Arrays::).
`-f'
Use function names only.
evaluation (*note Shell Arithmetic::) is performed when the
variable is assigned a value.
+ `-l'
+ When the variable is assigned a value, all upper-case
+ characters are converted to lower-case. The upper-case
+ attribute is disabled.
+
`-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.
+ inherit the `DEBUG' and `RETURN' traps from the calling shell.
+ The trace attribute has no special meaning for variables.
+
+ `-u'
+ When the variable is assigned a value, all lower-case
+ characters are converted to upper-case. The lower-case
+ attribute is disabled.
`-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.
+ Using `+' instead of `-' turns off the attribute instead, with the
+ exceptions that `+a' may not be used to destroy an array variable
+ and `+r' will not remove the readonly attribute. When used in a
+ function, `declare' makes each NAME local, as with the `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
escape characters, even on systems where they are interpreted by
default. The `xpg_echo' shell option may be used to dynamically
determine whether or not `echo' expands these escape characters by
- default. `echo' interprets the following escape sequences:
+ default. `echo' does not interpret `--' to mean the end of
+ options.
+
+ `echo' interprets the following escape sequences:
`\a'
alert (bell)
backspace
`\c'
- suppress trailing newline
+ suppress further output
`\e'
escape
the eight-bit character whose value is the octal value NNN
(zero to three octal digits)
- `\NNN'
- the eight-bit character whose value is the octal value NNN
- (one to three octal 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 ...]
+ enable [-a] [-dnps] [-f FILENAME] [NAME ...]
Enable and disable builtin shell commands. Disabling a builtin
allows a disk command which has the same name as a shell builtin
to be executed without specifying a full pathname, even though the
there is an error loading a new builtin from a shared object.
`help'
- help [-s] [PATTERN]
+ help [-dms] [PATTERN]
Display helpful information about builtin commands. If PATTERN is
specified, `help' gives detailed help on all commands matching
- PATTERN, otherwise a list of the builtins is printed. The `-s'
- option restricts the information displayed to a short usage
- synopsis. The return status is zero unless no command matches
- PATTERN.
+ PATTERN, otherwise a list of the builtins is printed.
+
+ Options, if supplied, have the following meanings:
+
+ `-d'
+ Display a short description of each PATTERN
+
+ `-m'
+ Display the description of each PATTERN in a manpage-like
+ format
+
+ `-s'
+ Display only a short usage synopsis for each PATTERN
+
+ The return status is zero unless no command matches PATTERN.
`let'
let EXPRESSION [EXPRESSION]
The `let' builtin allows arithmetic to be performed on shell
variables. Each EXPRESSION is evaluated according to the rules
- given below in *Note Shell Arithmetic::. If the last EXPRESSION
+ given below in *note Shell Arithmetic::. If the last EXPRESSION
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
logout [N]
Exit a login shell, returning a status of N to the shell's parent.
+`mapfile'
+ mapfile [-n COUNT] [-O ORIGIN] [-s COUNT] [-t] [-u FD] [
+ -C CALLBACK] [-c QUANTUM] [ARRAY]
+ Read lines from the standard input into array variable ARRAY, or
+ from file descriptor FD if the `-u' option is supplied. The
+ variable `MAPFILE' is the default ARRAY. Options, if supplied,
+ have the following meanings:
+ `-n'
+ Copy at most COUNT lines. If COUNT is 0, all lines are
+ copied.
+
+ `-O'
+ Begin assigning to ARRAY at index ORIGIN. The default index
+ is 0.
+
+ `-s'
+ Discard the first COUNT lines read.
+
+ `-t'
+ Remove a trailing line from each line read.
+
+ `-u'
+ Read lines from file descriptor FD instead of the standard
+ input.
+
+ `-C'
+ Evaluate CALLBACK each time QUANTUMP lines are read. The
+ `-c' option specifies QUANTUM.
+
+ `-c'
+ Specify the number of lines read between each call to
+ CALLBACK.
+
+ If `-C' is specified without `-c', the default quantum is 5000.
+
+ If not supplied with an explicit origin, `mapfile' will clear ARRAY
+ before assigning to it.
+
+ `mapfile' returns successfully unless an invalid option or option
+ argument is supplied, or ARRAY is invalid or unassignable.
+
`printf'
- `printf' FORMAT [ARGUMENTS]
+ printf [-v VAR] FORMAT [ARGUMENTS]
Write the formatted ARGUMENTS to the standard output under the
control of the FORMAT. The FORMAT is a character string which
contains three types of objects: plain characters, which are
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 `-v' option causes the output to be assigned to the variable
+ VAR rather than being printed to the standard output.
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] [-d DELIM] [-n NCHARS] [-p PROMPT] [-t TIMEOUT] [-u FD] [NAME ...]
+ read [-ers] [-a ANAME] [-d DELIM] [-i TEXT] [-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
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:
+ times out (in which case the return code is greater than 128), 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
`-e'
Readline (*note Command Line Editing::) is used to obtain the
- line.
+ line. Readline uses the current (or default, if line editing
+ was not previously active) editing settings.
+
+ `-i TEXT'
+ If Readline is being used to read the line, TEXT is placed
+ into the editing buffer before editing begins.
`-n NCHARS'
`read' returns after reading NCHARS characters rather than
`-t TIMEOUT'
Cause `read' to time out and return failure if a complete
- line of input is not read within TIMEOUT seconds. This
- option has no effect if `read' is not reading input from the
- terminal or a pipe.
+ line of input is not read within TIMEOUT seconds. TIMEOUT
+ may be a decimal number with a fractional portion following
+ the decimal point. This option is only effective if `read'
+ is reading input from a terminal, pipe, or other special
+ file; it has no effect when reading from regular files. If
+ TIMEOUT is 0, `read' returns success if input is available on
+ the specified file descriptor, failure otherwise. The exit
+ status is greater than 128 if the timeout is exceeded.
`-u FD'
Read input from file descriptor FD.
-`shopt'
- shopt [-pqsu] [-o] [OPTNAME ...]
- Toggle the values of variables controlling optional shell behavior.
- With no options, or with the `-p' option, a list of all settable
- options is displayed, with an indication of whether or not each is
- set. The `-p' option causes output to be displayed in a form that
- may be reused as input. Other options have the following meanings:
- `-s'
- Enable (set) each OPTNAME.
+`source'
+ source FILENAME
+ A synonym for `.' (*note Bourne Shell Builtins::).
- `-u'
- Disable (unset) each OPTNAME.
-
- `-q'
- Suppresses normal output; the return status indicates whether
- the OPTNAME is set or unset. If multiple OPTNAME arguments
- are given with `-q', the return status is zero if all
- OPTNAMES are enabled; non-zero otherwise.
-
- `-o'
- Restricts the values of OPTNAME to be those defined for the
- `-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,
- respectively.
-
- Unless otherwise noted, the `shopt' options are disabled (off) 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
- option.
-
- The list of `shopt' options is:
- `cdable_vars'
- If this is set, an argument to the `cd' builtin command that
- is not a directory is assumed to be the name of a variable
- whose value is the directory to change to.
-
- `cdspell'
- If set, minor errors in the spelling of a directory component
- in a `cd' command will be corrected. The errors checked for
- are transposed characters, a missing character, and a
- character too many. If a correction is found, the corrected
- path is printed, and the command proceeds. This option is
- only used by interactive shells.
-
- `checkhash'
- If this is set, Bash checks that a command found in the hash
- table exists before trying to execute it. If a hashed
- command no longer exists, a normal path search is performed.
-
- `checkwinsize'
- If set, Bash checks the window size after each command and,
- if necessary, updates the values of `LINES' and `COLUMNS'.
-
- `cmdhist'
- If set, Bash attempts to save all lines of a multiple-line
- command in the same history entry. This allows easy
- re-editing of multi-line commands.
-
- `dotglob'
- If set, Bash includes filenames beginning with a `.' in the
- results of filename expansion.
-
- `execfail'
- If this is set, a non-interactive shell will not exit if it
- cannot execute the file specified as an argument to the `exec'
- builtin command. An interactive shell does not exit if `exec'
- fails.
-
- `expand_aliases'
- If set, aliases are expanded as described below under Aliases,
- *Note Aliases::. This option is enabled by default for
- interactive shells.
-
- `extglob'
- If set, the extended pattern matching features described above
- (*note Pattern Matching::) are enabled.
-
- `histappend'
- If set, the history list is appended to the file named by the
- value of the `HISTFILE' variable when the shell exits, rather
- than overwriting the file.
-
- `histreedit'
- If set, and Readline is being used, a user is given the
- opportunity to re-edit a failed history substitution.
-
- `histverify'
- If set, and Readline is being used, the results of history
- substitution are not immediately passed to the shell parser.
- Instead, the resulting line is loaded into the Readline
- editing buffer, allowing further modification.
-
- `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
- option is enabled by default.
-
- `huponexit'
- If set, Bash will send `SIGHUP' to all jobs when an
- interactive login shell exits (*note Signals::).
-
- `interactive_comments'
- Allow a word beginning with `#' to cause that word and all
- remaining characters on that line to be ignored in an
- interactive shell. This option is enabled by default.
-
- `lithist'
- If enabled, and the `cmdhist' option is enabled, multi-line
- 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
- `"The mail in MAILFILE has been read"' is displayed.
-
- `no_empty_cmd_completion'
- If set, and Readline is being used, Bash will not attempt to
- search the `PATH' for possible completions when completion is
- attempted on an empty line.
-
- `nocaseglob'
- If set, Bash matches filenames in a case-insensitive fashion
- when performing filename expansion.
-
- `nullglob'
- If set, Bash allows filename patterns which match no files to
- expand to a null string, rather than themselves.
-
- `progcomp'
- If set, the programmable completion facilities (*note
- 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::).
- 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.
-
- `shift_verbose'
- If this is set, the `shift' builtin prints an error message
- when the shift count exceeds the number of positional
- parameters.
-
- `sourcepath'
- If set, the `source' builtin uses the value of `PATH' to find
- the directory containing the file supplied as an argument.
- This option is enabled by default.
-
- `xpg_echo'
- 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
- option.
-
-`source'
- source FILENAME
- A synonym for `.' (*note Bourne Shell Builtins::).
-
-`type'
- type [-afptP] [NAME ...]
- For each NAME, indicate how it would be interpreted if used as a
- command name.
+`type'
+ type [-afptP] [NAME ...]
+ For each NAME, indicate how it would be interpreted if used as a
+ command name.
If the `-t' option is used, `type' prints a single word which is
one of `alias', `function', `builtin', `file' or `keyword', if
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.
+ The return status is zero if all of the NAMES are found, non-zero
+ if any are not 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.
`ulimit'
- ulimit [-acdflmnpstuvSH] [LIMIT]
+ ulimit [-abcdefilmnpqrstuvxHST] [LIMIT]
`ulimit' provides control over the resources available to processes
started by the shell, on systems that allow such control. If an
option is given, it is interpreted as follows:
`-a'
All current limits are reported.
+ `-b'
+ The maximum socket buffer size.
+
`-c'
The maximum size of core files created.
`-d'
The maximum size of a process's data segment.
+ `-e'
+ The maximum scheduling priority ("nice").
+
`-f'
- The maximum size of files created by the shell.
+ The maximum size of files written by the shell and its
+ children.
+
+ `-i'
+ The maximum number of pending signals.
`-l'
The maximum size that may be locked into memory.
`-p'
The pipe buffer size.
+ `-q'
+ The maximum number of bytes in POSIX message queues.
+
+ `-r'
+ The maximum real-time scheduling priority.
+
`-s'
The maximum stack size.
`-v'
The maximum amount of virtual memory available to the process.
+ `-x'
+ The maximum number of file locks.
+
+ `-T'
+ The maximum number of threads.
+
+
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
+ respectively. A hard limit cannot be increased by a non-root user
+ once it is set; a soft limit may be increased up to the value of
+ the hard limit. 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,
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::.
+ 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
+File: bashref.info, Node: Modifying Shell Behavior, Next: Special Builtins, Prev: Bash Builtins, Up: Shell Builtin Commands
-The Set Builtin
-===============
+4.3 Modifying Shell Behavior
+============================
- This builtin is so complicated that it deserves its own section.
+* Menu:
+
+* The Set Builtin:: Change the values of shell attributes and
+ positional parameters.
+* The Shopt Builtin:: Modify shell optional behavior.
+
+\1f
+File: bashref.info, Node: The Set Builtin, Next: The Shopt Builtin, Up: Modifying Shell Behavior
+
+4.3.1 The Set Builtin
+---------------------
+
+This builtin is so complicated that it deserves its own section. `set'
+allows you to change the values of shell options and set the positional
+parameters, or to display the names and values of shell variables.
`set'
- set [--abefhkmnptuvxBCHP] [-o OPTION] [ARGUMENT ...]
+ set [--abefhkmnptuvxBCEHPT] [-o OPTION] [ARGUMENT ...]
+ set [+abefhkmnptuvxBCEHPT] [+o OPTION] [ARGUMENT ...]
If no options or arguments are supplied, `set' displays the names
and values of all shell variables and functions, sorted according
- to the current locale, in a format that may be reused as input.
+ to the current locale, in a format that may be reused as input for
+ setting or resetting the currently-set variables. Read-only
+ variables cannot be reset. In POSIX mode, only shell variables
+ are listed.
When options are supplied, they set or unset shell attributes.
Options, if specified, have the following meanings:
`-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 `!'. A trap
- on `ERR', if set, is executed before the shell exits.
+ 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 command executed in a `&&' or `||b' list,
+ any command in a pipeline but the last, or if the command's
+ return status is being inverted using `!'. Failing simple
+ commands that are part of shell functions or command lists
+ enclosed in braces or parentheses satisfying the above
+ conditions do not cause the shell to exit. A trap on `ERR',
+ if set, is executed before the shell exits.
`-f'
Disable file name generation (globbing).
`emacs'
Use an `emacs'-style line editing interface (*note
- Command Line Editing::).
+ Command Line Editing::). This also affects the editing
+ interface used for `read -e'.
`errexit'
Same as `-e'.
+ `errtrace'
+ Same as `-E'.
+
+ `functrace'
+ Same as `-T'.
+
`hashall'
Same as `-h'.
Same as `-H'.
`history'
- Enable command history, as described in *Note Bash
+ Enable command history, as described in *note Bash
History Facilities::. This option is on by default in
interactive shells.
`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.
+ differs from the POSIX standard to match the standard
+ (*note Bash POSIX Mode::). This is intended to make
+ Bash behave as a strict superset of that standard.
`privileged'
Same as `-p'.
Same as `-v'.
`vi'
- Use a `vi'-style line editing interface.
+ Use a `vi'-style line editing interface. This also
+ affects the editing interface used for `read -e'.
`xtrace'
Same as `-x'.
`-p'
Turn on privileged mode. In this mode, the `$BASH_ENV' and
`$ENV' files are not processed, shell functions are not
- inherited from the environment, and the `SHELLOPTS' variable,
- if it appears in the environment, is ignored. If the shell
- is started with the effective user (group) id not equal to the
- real user (group) id, and the `-p' option is not supplied,
- these actions are taken and the effective user id is set to
- the real user id. If the `-p' option is supplied at startup,
- the effective user id is not reset. Turning this option off
- causes the effective user and group ids to be set to the real
- user and group ids.
+ inherited from the environment, and the `SHELLOPTS', `CDPATH'
+ and `GLOBIGNORE' variables, if they appear in the
+ environment, are ignored. If the shell is started with the
+ effective user (group) id not equal to the real user (group)
+ id, and the `-p' option is not supplied, these actions are
+ taken and the effective user id is set to the real user id.
+ If the `-p' option is supplied at startup, the effective user
+ id is not reset. Turning this option off causes the
+ effective user and group ids to be set to the real user and
+ group ids.
`-t'
Exit after reading and executing one command.
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, `for' commands, `case'
+ commands, `select' commands, and arithmetic `for' 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
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
$ cd ..; pwd
/usr/local
+ `-T'
+ If set, any trap on `DEBUG' and `RETURN' are inherited by
+ shell functions, command substitutions, and commands executed
+ in a subshell environment. The `DEBUG' and `RETURN' traps
+ are normally not inherited in such cases.
+
`--'
If no arguments follow this option, then the positional
parameters are unset. Otherwise, the positional parameters
supplied.
\1f
-File: bashref.info, Node: Special Builtins, Prev: The Set Builtin, Up: Shell Builtin Commands
+File: bashref.info, Node: The Shopt Builtin, Prev: The Set Builtin, Up: Modifying Shell Behavior
-Special Builtins
-================
+4.3.2 The Shopt Builtin
+-----------------------
+
+This builtin allows you to change additional shell optional behavior.
- 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
+`shopt'
+ shopt [-pqsu] [-o] [OPTNAME ...]
+ Toggle the values of variables controlling optional shell behavior.
+ With no options, or with the `-p' option, a list of all settable
+ options is displayed, with an indication of whether or not each is
+ set. The `-p' option causes output to be displayed in a form that
+ may be reused as input. Other options have the following meanings:
+
+ `-s'
+ Enable (set) each OPTNAME.
+
+ `-u'
+ Disable (unset) each OPTNAME.
+
+ `-q'
+ Suppresses normal output; the return status indicates whether
+ the OPTNAME is set or unset. If multiple OPTNAME arguments
+ are given with `-q', the return status is zero if all
+ OPTNAMES are enabled; non-zero otherwise.
+
+ `-o'
+ Restricts the values of OPTNAME to be those defined for the
+ `-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,
+ respectively.
+
+ Unless otherwise noted, the `shopt' options are disabled (off) 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
+ option.
+
+ The list of `shopt' options is:
+ `autocd'
+ If set, a command name that is the name of a directory is
+ executed as if it were the argument to the `cd' command.
+ This option is only used by interactive shells.
+
+ `cdable_vars'
+ If this is set, an argument to the `cd' builtin command that
+ is not a directory is assumed to be the name of a variable
+ whose value is the directory to change to.
+
+ `cdspell'
+ If set, minor errors in the spelling of a directory component
+ in a `cd' command will be corrected. The errors checked for
+ are transposed characters, a missing character, and a
+ character too many. If a correction is found, the corrected
+ path is printed, and the command proceeds. This option is
+ only used by interactive shells.
+
+ `checkhash'
+ If this is set, Bash checks that a command found in the hash
+ table exists before trying to execute it. If a hashed
+ command no longer exists, a normal path search is performed.
+
+ `checkjobs'
+ If set, Bash lists the status of any stopped and running jobs
+ before exiting an interactive shell. If any jobs are
+ running, this causes the exit to be deferred until a second
+ exit is attempted without an intervening command (*note Job
+ Control::). The shell always postpones exiting if any jobs
+ are stopped.
+
+ `checkwinsize'
+ If set, Bash checks the window size after each command and,
+ if necessary, updates the values of `LINES' and `COLUMNS'.
+
+ `cmdhist'
+ If set, Bash attempts to save all lines of a multiple-line
+ command in the same history entry. This allows easy
+ re-editing of multi-line commands.
+
+ `compat31'
+ If set, Bash changes its behavior to that of version 3.1 with
+ respect to quoted arguments to the conditional command's =~
+ operator.
+
+ `dirspell'
+ If set, Bash attempts spelling correction on directory names
+ during word completion if the directory name initially
+ supplied does not exist.
+
+ `dotglob'
+ If set, Bash includes filenames beginning with a `.' in the
+ results of filename expansion.
+
+ `execfail'
+ If this is set, a non-interactive shell will not exit if it
+ cannot execute the file specified as an argument to the `exec'
+ builtin command. An interactive shell does not exit if `exec'
+ fails.
+
+ `expand_aliases'
+ If set, aliases are expanded as described below under Aliases,
+ *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.
+
+ 4. `BASH_ARGC' and `BASH_ARGV' are updated as described in
+ their descriptions (*note Bash Variables::).
+
+ 5. Function tracing is enabled: command substitution,
+ shell functions, and subshells invoked with `( COMMAND
+ )' inherit the `DEBUG' and `RETURN' traps.
+
+ 6. Error tracing is enabled: command substitution, shell
+ functions, and subshells invoked with `( COMMAND )'
+ inherit the `ERROR' trap.
+
+ `extglob'
+ If set, the extended pattern matching features described above
+ (*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.
+
+ `globstar'
+ If set, the pattern `**' used in a filename expansion context
+ will match a files and zero or more directories and
+ subdirectories. If the pattern is followed by a `/', only
+ directories and subdirectories match.
+
+ `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
+ value of the `HISTFILE' variable when the shell exits, rather
+ than overwriting the file.
+
+ `histreedit'
+ If set, and Readline is being used, a user is given the
+ opportunity to re-edit a failed history substitution.
+
+ `histverify'
+ If set, and Readline is being used, the results of history
+ substitution are not immediately passed to the shell parser.
+ Instead, the resulting line is loaded into the Readline
+ editing buffer, allowing further modification.
+
+ `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
+ option is enabled by default.
+
+ `huponexit'
+ If set, Bash will send `SIGHUP' to all jobs when an
+ interactive login shell exits (*note Signals::).
+
+ `interactive_comments'
+ Allow a word beginning with `#' to cause that word and all
+ remaining characters on that line to be ignored in an
+ interactive shell. This option is enabled by default.
+
+ `lithist'
+ If enabled, and the `cmdhist' option is enabled, multi-line
+ 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
+ `"The mail in MAILFILE has been read"' is displayed.
+
+ `no_empty_cmd_completion'
+ If set, and Readline is being used, Bash will not attempt to
+ search the `PATH' for possible completions when completion is
+ attempted on an empty line.
+
+ `nocaseglob'
+ If set, Bash matches filenames in a case-insensitive fashion
+ when performing filename expansion.
+
+ `nocasematch'
+ If set, Bash matches patterns in a case-insensitive fashion
+ when performing matching while executing `case' or `[['
+ conditional commands.
+
+ `nullglob'
+ If set, Bash allows filename patterns which match no files to
+ expand to a null string, rather than themselves.
+
+ `progcomp'
+ If set, the programmable completion facilities (*note
+ Programmable Completion::) are enabled. This option is
+ enabled by default.
+
+ `promptvars'
+ 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.
+
+ `shift_verbose'
+ If this is set, the `shift' builtin prints an error message
+ when the shift count exceeds the number of positional
+ parameters.
+
+ `sourcepath'
+ If set, the `source' builtin uses the value of `PATH' to find
+ the directory containing the file supplied as an argument.
+ This option is enabled by default.
+
+ `xpg_echo'
+ 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
+ option.
+
+
+\1f
+File: bashref.info, Node: Special Builtins, Prev: Modifying Shell Behavior, Up: Shell Builtin Commands
+
+4.4 Special Builtins
+====================
+
+For historical reasons, the POSIX 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:
1. Special builtins are found before shell functions during command
When Bash is not executing in POSIX mode, these builtins behave no
differently than the rest of the Bash builtin commands. The Bash POSIX
-mode is described in *Note Bash POSIX Mode::.
+mode is described in *note Bash POSIX Mode::.
These are the POSIX special builtins:
break : . continue eval exec exit export readonly return set
\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
`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:
`BASH'
The full pathname used to execute the current instance of Bash.
+`BASHPID'
+ Expands to the process id of the current Bash process. This
+ differs from `$$' under certain circumstances, such as subshells
+ that do not require Bash to be re-initialized.
+
+`BASH_ALIASES'
+ An associative array variable whose members correspond to the
+ internal list of aliases as maintained by the `alias' builtin
+ (*note Bourne Shell Builtins::). Elements added to this array
+ appear in the alias list; unsetting array elements cause aliases
+ to be removed from the alias list.
+
+`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'. The shell sets `BASH_ARGC' only when in
+ extended debugging mode (see *note The Shopt Builtin:: for a
+ description of the `extdebug' option to the `shopt' builtin).
+
+`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'. The shell
+ sets `BASH_ARGV' only when in extended debugging mode (see *note
+ The Shopt Builtin:: for a description of the `extdebug' option to
+ the `shopt' builtin).
+
+`BASH_CMDS'
+ An associative array variable whose members correspond to the
+ internal hash table of commands as maintained by the `hash' builtin
+ (*note Bourne Shell Builtins::). Elements added to this array
+ appear in the hash table; unsetting array elements cause commands
+ to be removed from the hash table.
+
+`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]}' was called (or `${BASH_LINENO[$i-1]}' if
+ referenced within another shell function). The corresponding
+ source file name is `${BASH_SOURCE[$i]}'. 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
`BASH_VERSINFO[5]'
The value of `MACHTYPE'.
+
+`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
functions and external commands invoked by the programmable
completion facilities (*note Programmable Completion::).
+`COMP_TYPE'
+ Set to an integer value corresponding to the type of completion
+ attempted that caused a completion function to be called: TAB, for
+ normal completion, `?', for listing completions after successive
+ tabs, `!', for listing alternatives on partial word completion,
+ `@', to list completions if the word is not unmodified, or `%',
+ for menu completion. This variable is available only in shell
+ functions and external commands invoked by the programmable
+ completion facilities (*note Programmable Completion::).
+
+`COMP_KEY'
+ The key (or final key of a key sequence) used to invoke the current
+ completion function.
+
+`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::).
+ current command line. The words are split on shell metacharacters
+ as the shell parser would separate them. 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
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.
names. A sample value is `.o:~'
`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 return an error status. If
- `FUNCNAME' is unset, it loses its special properties, even if it
- is subsequently reset.
+ 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
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
`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.
+ if necessary, by removing the oldest entries, 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
The maximum number of commands to remember on the history list.
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. This uses the
+ history comment character to distinguish timestamps from other
+ history lines.
+
`HOSTFILE'
Contains the name of a file in the same format as `/etc/hosts' that
should be read when the shell needs to complete a hostname. The
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'
If set, the value is interpreted as a command to execute before
the printing of each primary prompt (`$PS1').
+`PROMPT_DIRTRIM'
+ If set to a number greater than zero, the value is used as the
+ number of trailing directory components to retain when expanding
+ the `\w' and `\W' prompt string escapes (*note Printing a
+ Prompt::). Characters removed are replaced with an ellipsis.
+
`PS3'
The value of this variable is used as the prompt for the `select'
command. If this variable is not set, the `select' command
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
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
+ In an interactive 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.
+`TMPDIR'
+ If set, Bash uses its value as the name of a directory in which
+ Bash creates temporary files for the shell's use.
+
`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] [-O SHOPT_OPTION] [ARGUMENT ...]
bash [long-opt] [-abefhkmnptuvxdBCDHP] [-o OPTION] [-O SHOPT_OPTION] -c STRING [ARGUMENT ...]
that you can use. These options must appear on the command line before
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 The Shopt
+ Builtin:: 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
- the standard ouput in the GNU `gettext' PO (portable object) file
+ the standard output in the GNU `gettext' PO (portable object) file
format. Equivalent to `-D' except for the output format.
`--dump-strings'
Equivalent to `-D'.
`--help'
- Display a usage message on standard output and exit sucessfully.
+ Display a usage message on standard output and exit successfully.
`--init-file FILENAME'
`--rcfile FILENAME'
`--posix'
Change the behavior of Bash where the default operation differs
- from the POSIX 1003.2 standard to match the standard. This is
- intended to make Bash behave as a strict superset of that
- standard. *Note Bash POSIX Mode::, for a description of the Bash
- POSIX mode.
+ from the POSIX standard to match the standard. This is intended
+ to make Bash behave as a strict superset of that standard. *Note
+ Bash POSIX Mode::, for a description of the Bash POSIX mode.
`--restricted'
Make the shell a restricted shell (*note The Restricted Shell::).
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.
`-i'
Force the shell to run interactively. Interactive shells are
- described in *Note Interactive Shells::.
+ described in *note Interactive Shells::.
`-l'
Make this shell act as if it had been directly invoked by login.
`-D'
A list of all double-quoted strings preceded by `$' is printed on
- the standard ouput. These are the strings that are subject to
+ the standard output. 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
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
+ builtin (*note The Shopt Builtin::). 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
processing. Any arguments after the `--' are treated as filenames
and arguments.
+
A _login_ shell is one whose first character of argument zero is
`-', or one invoked with the `--login' option.
\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 describes 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::.
+ 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
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
-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'
-option may be used to inhibit this behavior, and the `--rcfile' option
-may be used to force another file to be read, but `rshd' does not
-generally invoke the shell with those options or allow them to be
-specified.
+Bash attempts to determine when it is being run with its standard input
+connected to a a network connection, as if by the remote shell daemon,
+usually `rshd', or the secure shell daemon `sshd'. If Bash determines
+it is being run in this fashion, 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' option may be used to inhibit this
+behavior, and the `--rcfile' option may be used to force another file
+to be read, but `rshd' does not generally invoke the shell with those
+options or allow them to be specified.
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,
-unless `-s' is specified, without specifiying the `-c' option, and
-whose input and output are both connected to terminals (as determined
+An interactive shell is one started without non-option arguments,
+unless `-s' is specified, without specifying the `-c' option, and 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
\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:
\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
+ 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
((*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 `huponexit' shell option has been enabled (*note Signals::).
12. The `-n' invocation option is ignored, and `set -n' has no effect
(*note The Set Builtin::).
20. Simple spelling correction for directory arguments to the `cd'
builtin is enabled by default (see the description of the `cdspell'
- option to the `shopt' builtin in *Note Bash Builtins::).
+ option to the `shopt' builtin in *note The Shopt Builtin::).
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
\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
`/dev/stdin', `/dev/stdout', or `/dev/stderr', file descriptor 0, 1, or
2, respectively, is checked.
+ Unless otherwise specified, primaries that operate on files follow
+symbolic links and operate on the target of the link, rather than the
+link itself.
+
`-a FILE'
True if FILE exists.
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 fixed-width 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.
+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
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
-and uppercase letters may be used interchangably to represent numbers
+and uppercase letters may be used interchangeably to represent numbers
between 10 and 35.
Operators are evaluated in order of precedence. Sub-expressions in
\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.
(*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::).
+the `expand_aliases' shell option is set using `shopt' (*note The Shopt
+Builtin::).
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
-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
-are zero-based.
+Bash provides one-dimensional indexed and associative array variables.
+Any variable may be used as an indexed 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. Indexed arrays are referenced using integers
+(including arithmetic expressions (*note Shell Arithmetic::) and are
+zero-based; associative arrays use arbitrary strings.
- An array is created automatically if any variable is assigned to
-using the syntax
+ An indexed array is created automatically if any variable is
+assigned to using the syntax
name[SUBSCRIPT]=VALUE
The SUBSCRIPT is treated as an arithmetic expression that must evaluate
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.
-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.
+ Associative arrays are created using
+ declare -A NAME.
+
+ 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. Indexed array
+assignments do not require the bracket and subscript. When assigning
+to indexed arrays, 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.
+
+ When assigning to an associative array, the subscript is required.
-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
-accepted by the `declare' builtin. Individual array elements may be
-assigned to using the `name['SUBSCRIPT`]='VALUE syntax introduced above.
+ This syntax is also accepted by the `declare' builtin. Individual
+array elements may be assigned to using the `name['SUBSCRIPT`]='VALUE
+syntax introduced above.
Any element of an array may be referenced using
`${name['SUBSCRIPT`]}'. The braces are required to avoid conflicts
the value of each array member separated by the first character of the
`IFS' variable, and `${name[@]}' expands each element of NAME to a
separate word. When there are no array members, `${name[@]}' expands
-to nothing. This is analogous to the expansion of the special
-parameters `@' and `*'. `${#name['SUBSCRIPT`]}' expands to the length
-of `${name['SUBSCRIPT`]}'. If SUBSCRIPT is `@' or `*', the expansion
-is the number of elements in the array. Referencing an array variable
-without a subscript is equivalent to referencing element zero.
+to nothing. If the double-quoted expansion occurs within a word, the
+expansion of the first parameter is joined with the beginning part of
+the original word, and the expansion of the last parameter is joined
+with the last part of the original word. This is analogous to the
+expansion of the special parameters `@' and `*'.
+`${#name['SUBSCRIPT`]}' expands to the length of `${name['SUBSCRIPT`]}'.
+If SUBSCRIPT is `@' or `*', the expansion is the number of elements in
+the array. Referencing an array variable without a subscript is
+equivalent to referencing with a subscript of 0.
The `unset' builtin is used to destroy arrays. `unset'
-NAME[SUBSCRIPT] destroys the array element at index SUBSCRIPT. `unset'
-NAME, where NAME is an array, removes the entire array. A subscript of
-`*' or `@' also removes the entire array.
+NAME[SUBSCRIPT] destroys the array element at index SUBSCRIPT. Care
+must be taken to avoid unwanted side effects caused by filename
+generation. `unset' NAME, where NAME is an array, removes the entire
+array. A subscript of `*' or `@' also removes the entire array.
The `declare', `local', and `readonly' builtins each accept a `-a'
-option to specify an array. The `read' builtin accepts a `-a' option
-to assign a list of words read from the standard input to an array, and
-can read values from the standard input into individual array elements.
-The `set' and `declare' builtins display array values in a way that
-allows them to be reused as input.
+option to specify an indexed array and a `-A' option to specify an
+associative array. The `read' builtin accepts a `-a' option to assign
+a list of words read from the standard input to an array, and can read
+values from the standard input into individual array elements. The
+`set' and `declare' builtins display array values in a way that allows
+them to be reused as input.
\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]
manipulated.
`pushd'
- pushd [DIR | +N | -N] [-n]
+ pushd [-n] [+N | -N | DIR ]
Save the current directory on the top of the directory stack and
then `cd' to DIR. With no arguments, `pushd' exchanges the top
two directories.
+ `-n'
+ Suppresses the normal change of directory when adding
+ directories to the stack, so that only the stack is
+ manipulated.
+
`+N'
Brings the Nth directory (counting from the left of the list
printed by `dirs', starting with zero) to the top of the list
printed by `dirs', starting with zero) to the top of the list
by rotating the stack.
- `-n'
- Suppresses the normal change of directory when adding
- directories to the stack, so that only the stack is
- manipulated.
-
`DIR'
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.
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 (uses the `$PROMPT_DIRTRIM' variable).
`\W'
- The basename of `$PWD'.
+ The basename of `$PWD', with `$HOME' abbreviated with a tilde.
`\!'
The history number of this command.
\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' or
-`-r' option is supplied at invocation, the shell becomes restricted. A
+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 or not performed:
\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 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.
is stopped is `Stopped(SIGNAME)', where SIGNAME is, for example,
`SIGTSTP'.
- 4. Reserved words may not be aliased.
+ 4. The `bg' builtin uses the required format to describe each job
+ placed in the background, which does not include an indication of
+ whether the job is the current or previous job.
- 5. The POSIX 1003.2 `PS1' and `PS2' expansions of `!' to the history
- number and `!!' to `!' are enabled, and parameter expansion is
- performed on the values of `PS1' and `PS2' regardless of the
- setting of the `promptvars' option.
+ 5. Reserved words appearing in a context where reserved words are
+ recognized do not undergo alias expansion.
- 6. Interactive comments are enabled by default. (Bash has them on by
- default anyway.)
+ 6. The POSIX `PS1' and `PS2' expansions of `!' to the history number
+ and `!!' to `!' are enabled, and parameter expansion is performed
+ on the values of `PS1' and `PS2' regardless of the setting of the
+ `promptvars' option.
- 7. The POSIX 1003.2 startup files are executed (`$ENV') rather than
- the normal Bash files.
+ 7. The POSIX startup files are executed (`$ENV') rather than the
+ normal Bash files.
8. Tilde expansion is only performed on assignments preceding a
command name, rather than on all assignment statements on the line.
value of `$HISTFILE').
10. The output of `kill -l' prints all the signal names on a single
- line, separated by spaces.
+ line, separated by spaces, without the `SIG' prefix.
- 11. Non-interactive shells exit if FILENAME in `.' FILENAME is not
+ 11. The `kill' builtin does not accept signal names with a `SIG'
+ prefix.
+
+ 12. Non-interactive shells exit if FILENAME in `.' FILENAME is not
found.
- 12. Non-interactive shells exit if a syntax error in an arithmetic
+ 13. Non-interactive shells exit if a syntax error in an arithmetic
expansion results in an invalid expression.
- 13. Redirection operators do not perform filename expansion on the word
+ 14. Redirection operators do not perform filename expansion on the word
in the redirection unless the shell is interactive.
- 14. Redirection operators do not perform word splitting on the word in
+ 15. Redirection operators do not perform word splitting on the word in
the redirection.
- 15. Function names must be valid shell `name's. That is, they may not
+ 16. Function names must be valid shell `name's. That is, they may not
contain characters other than letters, digits, and underscores, and
may not start with a digit. Declaring a function with an invalid
name causes a fatal syntax error in non-interactive shells.
- 16. POSIX 1003.2 `special' builtins are found before shell functions
- during command lookup.
+ 17. POSIX special builtins are found before shell functions during
+ command lookup.
- 17. If a POSIX 1003.2 special builtin returns an error status, a
+ 18. If a POSIX special builtin returns an error status, a
non-interactive shell exits. The fatal errors are those listed in
- the POSIX.2 standard, and include things like passing incorrect
+ the POSIX standard, and include things like passing incorrect
options, redirection errors, variable assignment errors for
assignments preceding the command name, and so on.
- 18. If the `cd' builtin finds a directory to change to using
- `$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
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
22. Process substitution is not available.
- 23. Assignment statements preceding POSIX 1003.2 special builtins
- persist in the shell environment after the builtin completes.
+ 23. Assignment statements preceding POSIX special builtins persist in
+ the shell environment after the builtin completes.
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.
+ in the format required by POSIX.
26. The `trap' builtin displays signal names without the leading `SIG'.
- 27. The `.' and `source' builtins do not search the current directory
+ 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, unless that argument consists solely of
+ digits and is a valid signal number. 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'.
- 28. Subshells spawned to execute command substitutions inherit the
+ 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.
- 29. Alias expansion is always enabled, even in non-interactive shells.
+ 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.
- 30. When the `set' builtin is invoked without options, it does not
+ 32. When the `set' builtin is invoked without options, it does not
display shell function names and definitions.
- 31. When the `set' builtin is invoked without options, it displays
+ 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.
- 32. When the `cd' builtin is invoked in LOGICAL mode, and the pathname
+ 34. When the `cd' builtin is invoked in LOGICAL mode, and the pathname
constructed from `$PWD' and the directory name supplied as an
argument does not refer to an existing directory, `cd' will fail
instead of falling back to PHYSICAL mode.
- There is other POSIX 1003.2 behavior that Bash does not implement.
-Specifically:
+ 35. When the `pwd' builtin is supplied the `-P' option, it resets
+ `$PWD' to a pathname containing no symlinks.
+
+ 36. The `pwd' builtin verifies that the value it prints is the same as
+ the current directory, even if it is not asked to check the file
+ system with the `-P' option.
+
+ 37. When listing the history, the `fc' builtin does not include an
+ indication of whether or not a history entry has been modified.
+
+ 38. The default editor used by `fc' is `ed'.
+
+ 39. The `type' and `command' builtins will not report a non-executable
+ file as having been found, though the shell will attempt to
+ execute such a file if it is the only so-named file found in
+ `$PATH'.
+
+ 40. The `vi' editing mode will invoke the `vi' editor directly when
+ the `v' command is run, instead of checking `$VISUAL' and
+ `$EDITOR'.
- 1. Assignment statements affect the execution environment of all
- builtins, not just special ones.
+ 41. When the `xpg_echo' option is enabled, Bash does not attempt to
+ interpret any arguments to `echo' as options. Each argument is
+ displayed, after escape characters are converted.
- 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.
+ 42. The `ulimit' builtin uses a block size of 512 bytes for the `-c'
+ and `-f' options.
- 3. When using `.' to source a shell script found in `$PATH', bash
- checks execute permission bits rather than read permission bits,
- just as if it were searching for a command.
+ There is other POSIX behavior that Bash does not implement by
+default even when in POSIX mode. Specifically:
+
+ 1. The `fc' builtin checks `$EDITOR' as a program to edit history
+ entries if `FCEDIT' is unset, rather than defaulting directly to
+ `ed'. `fc' uses `ed' if `EDITOR' is unset.
+
+ 2. As noted above, Bash requires the `xpg_echo' option to be enabled
+ for the `echo' builtin to be fully conformant.
+
+
+ Bash can be configured to be POSIX-conformant by default, by
+specifying the `--enable-strict-posix-default' to `configure' when
+building (*note Optional Features::).
\1f
-File: bashref.info, Node: Job Control, Next: Using History Interactively, Prev: Bash Features, Up: Top
+File: bashref.info, Node: Job Control, Next: Command Line Editing, 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
be discarded.
There are a number of ways to refer to a job in the shell. The
-character `%' introduces a job name.
+character `%' introduces a job specification (JOBSPEC).
Job number `n' may be referred to as `%n'. The symbols `%%' and
`%+' refer to the shell's notion of the current job, which is the last
-job stopped while it was in the foreground or started in the
-background. The previous job may be referenced using `%-'. In output
-pertaining to jobs (e.g., the output of the `jobs' command), the
-current job is always flagged with a `+', and the previous job with a
-`-'.
+job stopped while it was in the foreground or started in the background.
+A single `%' (with no accompanying job specification) also refers to
+the current job. The previous job may be referenced using `%-'. If
+there is only a single job, `%+' and `%-' can both be used to refer to
+that job. In output pertaining to jobs (e.g., the output of the `jobs'
+command), the current job is always flagged with a `+', and the
+previous job with a `-'.
A job may also be referred to using a prefix of the name used to
start it, or using a substring that appears in its command line. For
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
-prints a message warning that there are stopped jobs. The `jobs'
+ If an attempt to exit Bash is made while jobs are stopped, (or
+running, if the `checkjobs' option is enabled - see *note The Shopt
+Builtin::), the shell prints a warning message, and if the `checkjobs'
+option is enabled, lists the jobs and their statuses. 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
-another warning, and the stopped jobs are terminated.
+another warning, and any stopped jobs are terminated.
\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]
- Resume the suspended job JOBSPEC in the background, as if it had
+ bg [JOBSPEC ...]
+ Resume each suspended job JOBSPEC in the background, as if it had
been started with `&'. If JOBSPEC is not supplied, the current
job is used. The return status is zero unless it is run when job
- control is not enabled, or, when run with job control enabled, if
- JOBSPEC was not found or JOBSPEC specifies a job that was started
- without job control.
+ control is not enabled, or, when run with job control enabled, any
+ JOBSPEC was not found or specifies a job that was started without
+ job control.
`fg'
fg [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]
- Wait until the child process specified by process ID PID or job
- specification JOBSPEC exits and return the exit status of the last
- command waited for. If a job spec is given, all processes in the
- job are waited for. If no arguments are given, all currently
+ wait [JOBSPEC or PID ...]
+ Wait until the child process specified by each process ID PID or
+ job specification JOBSPEC exits and return the exit status of the
+ last command waited for. If a job spec is given, all processes in
+ the job are waited for. If no arguments are given, all currently
active child processes are waited for, and the return status is
zero. If neither JOBSPEC nor PID specifies an active child process
of the shell, the return status is 127.
`suspend'
suspend [-f]
Suspend the execution of this shell until it receives a `SIGCONT'
- signal. The `-f' option means to suspend even if the shell is a
- login shell.
+ signal. A login shell cannot be suspended; the `-f' option can be
+ used to override this and force the suspension.
+
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
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
+File: bashref.info, Node: Command Line Editing, Next: Using History Interactively, Prev: Job Control, 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.
+Command line editing is enabled by default when using an interactive
+shell, unless the `--noediting' option is supplied at shell invocation.
+Line editing is also used when using the `-e' option to the `read'
+builtin command (*note Bash Builtins::). By default, the line editing
+commands are similar to those of emacs. A vi-style line editing
+interface is also available. Line editing can be enabled at any time
+using the `-o emacs' or `-o vi' options to the `set' builtin command
+(*note The Set Builtin::), or disabled using the `+o emacs' or `+o vi'
+options to `set'.
* Menu:
\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
\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
\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
\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
<DEL>. Here are some commands for moving more rapidly about the line.
\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.
Kill from the cursor to the previous whitespace. This is
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.
\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
\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
+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".
\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
directory. The name of this file is taken from the value of the shell
variable `INPUTRC'. If that variable is unset, the default is
-`~/.inputrc'.
+`~/.inputrc'. If that file does not exist or cannot be read, the
+ultimate default is `/etc/inputrc'.
When a program which uses the Readline library starts up, the init
file is read, and the key bindings are set.
\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
set editing-mode vi
Variable names and values, where appropriate, are recognized
- without regard to case.
+ without regard to case. Unrecognized variable names are ignored.
+
+ Boolean variables (those that can be set to on or off) are set to
+ on if the value is null or empty, ON (case-insensitive), or 1.
+ Any other value results in the variable being set to off.
The `bind -V' command lists the current Readline variable names
and values. *Note Bash Builtins::.
one is available. If set to `audible' (the default),
Readline attempts to ring the terminal's bell.
+ `bind-tty-special-chars'
+ If set to `on', Readline attempts to bind the control
+ characters treated specially by the kernel's terminal driver
+ to their Readline equivalents.
+
`comment-begin'
The string to insert at the beginning of the line when the
`insert-comment' command is executed. The default value is
completion in a case-insensitive fashion. The default value
is `off'.
+ `completion-prefix-display-length'
+ The length in characters of the common prefix of a list of
+ possible completions that is displayed without modification.
+ When set to a value greater than zero, common prefixes longer
+ than this value are replaced with an ellipsis when displaying
+ possible completions.
+
`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. This variable must be set to an integer value
- greater than or equal to 0. 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. A negative value means Readline should never ask.
+ 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 retrived with
- `previous-history' or `next-history'.
+ `history-preserve-point'
+ If set to `on', the history code attempts to place the point
+ (the current cursor position) at the same location on each
+ history line retrieved with `previous-history' or
+ `next-history'. The default is `off'.
+
+ `history-size'
+ Set the maximum number of history entries saved in the
+ history list. If set to zero, the number of entries in the
+ history list is not limited.
`horizontal-scroll-mode'
This variable can be set to either `on' or `off'. Setting it
sorted horizontally in alphabetical order, rather than down
the screen. The default is `off'.
+ `revert-all-at-newline'
+ If set to `on', Readline will undo all changes to history
+ lines before returning when `accept-line' is executed. By
+ default, history lines may be modified and retain individual
+ undo lists across calls to `readline'. The default is `off'.
+
`show-all-if-ambiguous'
This alters the default behavior of the completion functions.
If set to `on', words which have more than one possible
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
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.
+ a colon, and then the name of the command. There can be no space
+ between the key name and the colon - that will be interpreted as
+ part of the key name. 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).
`<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:
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.
\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
# 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
$if Bash
# edit the path
# Edit variable on current line.
"\M-\C-v": "\C-a\C-k$\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
set convert-meta off
-
+
# 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
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:
\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.
Move back to the start of the current or previous word. Words are
composed of letters and digits.
+`shell-forward-word ()'
+ Move forward to the end of the next word. Words are delimited by
+ non-quoted shell metacharacters.
+
+`shell-backward-word ()'
+ Move back to the start of the current or previous word. Words are
+ delimited by non-quoted shell metacharacters.
+
`clear-screen (C-l)'
Clear the screen and redraw the current line, leaving the current
line at the top of the screen.
`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 or Return)'
Accept the line regardless of where the cursor is. If this line is
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.
+ the Nth word from the end of the previous command. Once the
+ argument N is computed, the argument is extracted as if the `!N'
+ history expansion had been specified.
`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.
+ in turn. The history expansion facilities are used to extract the
+ last argument, as if the `!$' history expansion had been specified.
+
\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 at point. If point is at the beginning of
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 the word behind point. Word boundaries are the same as
`backward-word'.
+`shell-kill-word ()'
+ 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 `shell-forward-word'.
+
+`backward-kill-word ()'
+ Kill the word behind point. Word boundaries are the same as
+ `shell-backward-word'.
+
`unix-word-rubout (C-w)'
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.
\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
\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 perform completion on the text before point. The
against lines from the history list for possible completion
matches.
+`dabbrev-expand ()'
+ Attempt menu 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::).
+
\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
`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 `$FCEDIT',
+ result as shell commands. Bash attempts to invoke `$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.
\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
programmable completion facilities are invoked.
considered. The string is first split using the characters in the `IFS'
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
-the word being completed, and the matching words become the possible
-completions.
+variable expansion, command substitution, and arithmetic 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.
After these matches have been generated, any shell function or
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'
-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
-completed, and the third argument is the word preceding the word being
-completed on the current command line. No filtering of the generated
-completions against the word being completed is performed; the function
-or command has complete freedom in generating the matches.
+command or function is invoked, the `COMP_LINE', `COMP_POINT',
+`COMP_KEY', and `COMP_TYPE' variables are assigned values as described
+above (*note Bash 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 completed, and the third argument is the word preceding the
+word being completed on the current command line. No filtering of the
+generated completions against the word being completed is performed;
+the function or command has complete freedom in generating the matches.
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.
+use any of the shell facilities, including the `compgen' and `compopt'
+builtins 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
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 default' option was
-supplied to `complete' when the compspec was defined, Readline's
-default completion will be performed if the compspec generates no
+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,
\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 [-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 ...]'
+ `complete [-abcdefgjksuv] [-o COMP-OPTION] [-E] [-A ACTION] [-G GLOBPAT] [-W WORDLIST]
+ [-F FUNCTION] [-C COMMAND] [-X FILTERPAT]
+ [-P PREFIX] [-S SUFFIX] NAME [NAME ...]'
+ `complete -pr [-E] [NAME ...]'
Specify how arguments to each NAME should be completed. If the
`-p' option is supplied, or if no options are supplied, existing
completion specifications are printed in a way that allows them to
be reused as input. The `-r' option removes a completion
specification for each NAME, or, if no NAMEs are supplied, all
- completion specifications.
+ completion specifications. The `-E' option indicates that the
+ remaining options and actions should apply to "empty" command
+ completion; that is, completion attempted on a blank line.
The process of applying these completion specifications when word
completion is attempted is described above (*note Programmable
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.
`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'.
+ it can perform any filename-specific processing (like
+ adding a slash to directory names quoting special
+ characters, 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.
+ `plusdirs'
+ After any matches defined by the compspec are generated,
+ directory name completion is attempted and any matches
+ are added to the results of the other actions.
+
+
`-A ACTION'
The ACTION may be one of the following to generate a list of
possible completions:
for a NAME for which no specification exists, or an error occurs
adding a completion specification.
+`compopt'
+ `compopt' [-o OPTION] [+o OPTION] [NAME]
+ Modify completion options for each NAME according to the OPTIONs,
+ or for the currently-execution completion if no NAMEs are supplied.
+ If no OPTIONs are given, display the completion options for each
+ NAME or the current completion. The possible values of OPTION are
+ those valid for the `complete' builtin described above.
+
+ The return value is true unless an invalid option is supplied, an
+ attempt is made to modify the options for a NAME for which no
+ completion specification exists, or an output error occurs.
+
+
\1f
-File: bashref.info, Node: Using History Interactively, Next: Command Line Editing, Prev: Job Control, Up: Top
+File: bashref.info, Node: Using History Interactively, Next: Installing Bash, Prev: Command Line Editing, 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' 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,
+marked with the history comment character. When the history file is
+read, lines beginning with the history comment character followed
+immediately by a digit are interpreted as timestamps for the previous
+history line.
+
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.
\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'
- `fc [-e ENAME] [-nlr] [FIRST] [LAST]'
+ `fc [-e ENAME] [-lnr] [FIRST] [LAST]'
`fc -s [PAT=REP] [COMMAND]'
Fix Command. In the first form, a range of commands from FIRST to
With no options, display the history list with line numbers.
Lines prefixed with a `*' have been modified. An argument of N
- lists only the last N lines. Options, if supplied, have the
- following meanings:
+ 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
with Readline.
The shell allows control of the various characters used by the
-history expansion mechanism with the `histchars' variable.
+history expansion mechanism with the `histchars' variable, as explained
+above (*note Bash Variables::). The shell uses the history comment
+character to mark history timestamps when writing the history file.
* Menu:
\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'
Remove a trailing pathname component, leaving only the head.
`t'
- Remove all leading pathname components, leaving the tail.
+ Remove all leading pathname components, leaving the tail.
`r'
Remove a trailing suffix of the form `.SUFFIX', leaving the
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
+File: bashref.info, Node: Installing Bash, Next: Reporting Bugs, Prev: Using History Interactively, 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:
* Basic Installation:: Installation instructions.
-
* Compilers and Options:: How to set special options for various
systems.
-
* Compiling For Multiple Architectures:: How to compile Bash for more
than one kind of system from
the same source tree.
-
* Installation Names:: How to set the various paths used by the installation.
-
* Specifying the System Type:: How to configure Bash for a particular system.
-
* Sharing Defaults:: How to share default configuration values among GNU
programs.
-
* Operation Controls:: Options recognized by the configuration program.
-
* Optional Features:: How to enable and disable optional features when
building Bash.
\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:
\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', or
by specifying a value for the `DESTDIR' `make' variable when running
\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
+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
\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
Define if you are using the Andrew File System from Transarc.
`--with-bash-malloc'
- Use the Bash version of `malloc' in `lib/malloc/malloc.c'. This
- is not the same `malloc' that appears in GNU libc, but an older
- version derived from the 4.2 BSD `malloc'. This `malloc' is very
- fast, but wastes some space on each allocation. This option is
- enabled by default. The `NOTES' file contains a list of systems
- for which this should be turned off, and `configure' disables this
- option automatically for a number of systems.
+ Use the Bash version of `malloc' in the directory `lib/malloc'.
+ This is not the same `malloc' that appears in GNU libc, but an
+ older version originally derived from the 4.2 BSD `malloc'. This
+ `malloc' is very fast, but wastes some space on each allocation.
+ This option is enabled by default. The `NOTES' file contains a
+ list of systems for which this should be turned off, and
+ `configure' disables this option automatically for a number of
+ systems.
`--with-curses'
Use the curses library instead of the termcap library. This should
`--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 4.3 and later versions. If PREFIX is `yes' or
+ only with Readline 5.0 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
`--enable-brace-expansion'
Include `csh'-like brace expansion ( `b{a,b}c' ==> `bac bbc' ).
- See *Note Brace Expansion::, for a complete description.
+ See *note Brace Expansion::, for a complete description.
+
+`--enable-casemod-attributes'
+ Include support for case-modifying attributes in the `declare'
+ builtin and assignment statements. Variables with the UPPERCASE
+ attribute, for example, will have their values converted to
+ uppercase upon assignment.
+
+`--enable-casemod-expansion'
+ Include support for case-modifying word expansions.
`--enable-command-timing'
Include support for recognizing `time' as a reserved word and for
builtins and functions to be timed.
`--enable-cond-command'
- Include support for the `[[' conditional command (*note
+ 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-coprocesses'
+ Include support for coprocesses and the `coproc' reserved word
+ (*note Pipelines::).
+
+`--enable-debugger'
+ Include support for the bash debugger (distributed separately).
+
`--enable-directory-stack'
Include support for a `csh'-like directory stack and the `pushd',
`popd', and `dirs' builtins (*note The Directory Stack::).
`--enable-disabled-builtins'
Allow builtin commands to be invoked via `builtin xxx' even after
- `xxx' has been disabled using `enable -n xxx'. See *Note Bash
+ `xxx' has been disabled using `enable -n xxx'. See *note Bash
Builtins::, for details of the `builtin' and `enable' builtin
commands.
`--enable-extended-glob'
Include support for the extended pattern matching features
- described above under *Note Pattern Matching::.
+ described above under *note Pattern Matching::.
`--enable-help-builtin'
Include the `help' builtin, which displays help on shell builtins
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
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
- characters in the `$PS1', `$PS2', `$PS3', and `$PS4' prompt
- strings. See *Note Printing a Prompt::, for a complete list of
- prompt string escape sequences.
-
`--enable-progcomp'
Enable the programmable completion facilities (*note Programmable
Completion::). If Readline is not enabled, this option has no
effect.
+`--enable-prompt-string-decoding'
+ Turn on the interpretation of a number of backslash-escaped
+ characters in the `$PS1', `$PS2', `$PS3', and `$PS4' prompt
+ strings. See *note Printing a Prompt::, for a complete list of
+ prompt string escape sequences.
+
`--enable-readline'
Include support for command-line editing and history with the Bash
version of the Readline library (*note Command Line Editing::).
`--enable-restricted'
Include support for a "restricted shell". If this is enabled,
- Bash, when called as `rbash', enters a restricted mode. See *Note
+ Bash, when called as `rbash', enters a restricted mode. See *note
The Restricted Shell::, for a description of restricted mode.
`--enable-select'
Include the `select' builtin, which allows the generation of simple
menus (*note Conditional Constructs::).
+`--enable-separate-helpfiles'
+ Use external files for the documentation displayed by the `help'
+ builtin instead of storing the text internally.
+
+`--enable-single-help-strings'
+ Store the text displayed by the `help' builtin as a single string
+ for each help topic. This aids in translating the text to
+ different languages. You may need to disable this if your
+ compiler cannot handle very long string literals.
+
+`--enable-strict-posix-default'
+ Make Bash POSIX-conformant by default (*note Bash POSIX Mode::).
+
`--enable-usg-echo-default'
A synonym for `--enable-xpg-echo-default'.
default, without requiring the `-e' option. This sets the default
value of the `xpg_echo' shell option to `on', which makes the Bash
`echo' behave more like the version specified in the Single Unix
- Specification, version 2. *Note Bash Builtins::, for a
+ Specification, version 3. *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: GNU Free Documentation License, 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
+POSIX 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 in SVR4.2 as the baseline reference.
+included in SVR4.2 (the last version of the historical Bourne shell) as
+the baseline reference.
* Bash is POSIX-conformant, even where the POSIX specification
differs from traditional `sh' behavior (*note Bash POSIX Mode::).
the `bind' builtin.
* Bash provides a programmable word completion mechanism (*note
- Programmable Completion::), and two builtin commands, `complete'
- and `compgen', to manipulate it.
+ Programmable Completion::), and builtin commands `complete',
+ `compgen', and `compopt', to manipulate it.
* Bash has command history (*note Bash History Facilities::) and the
- `history' and `fc' builtins to manipulate it.
+ `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::).
* Bash implements the `!' keyword to negate the return value of a
pipeline (*note Pipelines::). Very useful when an `if' statement
- needs to act only if a test fails.
+ needs to act only if a test fails. The Bash `-o pipefail' option
+ to `set' will cause a pipeline to return a failure status if any
+ command fails.
* Bash has the `time' reserved word and command timing (*note
Pipelines::). The display of the timing statistics may be
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::), including optional regular expression matching.
+
+ * Bash provides optional case-insensitive matching for the `case' and
+ `[[' constructs.
* Bash includes brace expansion (*note Brace Expansion::) and tilde
expansion (*note Tilde Expansion::).
not normally do this unless the variables are explicitly marked
using the `export' command.
+ * Bash supports the `+=' assignment operator, which appends to the
+ value of the variable named on the left hand side.
+
* Bash includes the POSIX pattern removal `%', `#', `%%' and `##'
expansions to remove leading or trailing substrings from variable
values (*note Shell Parameter Expansion::).
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::).
+ * Bash implements the full set of POSIX filename expansion operators,
+ including CHARACTER CLASSES, EQUIVALENCE CLASSES, and COLLATING
+ SYMBOLS (*note Filename Expansion::).
* Bash implements extended pattern matching features when the
`extglob' shell option is enabled (*note Pattern Matching::).
operator, for directing standard output and standard error to the
same file (*note Redirections::).
+ * Bash includes the `<<<' redirection operator, allowing a string to
+ be used as the standard input to a command.
+
+ * Bash implements the `[n]<&WORD' and `[n]>&WORD' redirection
+ operators, which move one file descriptor to another.
+
* Bash treats a number of filenames specially when they are used in
redirection operators (*note Redirections::).
Builtins::).
* Bash includes the `shopt' builtin, for finer control of shell
- optional capabilities (*note Bash Builtins::), and allows these
- options to be set and unset at shell invocation (*note Invoking
- Bash::).
+ optional capabilities (*note The Shopt Builtin::), 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::).
+ * 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.
+ * 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
- unless the function has been given the `trace' attribute.
+ 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.
+ 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 unless the function has been given
+ the `trace' attribute or the `functrace' option has been enabled
+ using the `shopt' builtin.
* The Bash `type' builtin is more extensive and gives more
information about the names it finds (*note Bash Builtins::).
table (*note Job Control Builtins::) or suppress the sending of
`SIGHUP' to a job when the shell exits as the result of a `SIGHUP'.
+ * Bash includes a number of features to support a separate debugger
+ for shell scripts.
+
* The SVR4.2 shell has two privilege-related builtins (`mldmode' and
`priv') not present in Bash.
* The SVR4.2 `sh' uses a `TIMEOUT' variable like Bash uses `TMOUT'.
-More features unique to Bash may be found in *Note Bash Features::.
+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.
begins with a `-'.
* The SVR4.2 shell exits a script if any builtin fails; Bash exits a
- script only if one of the POSIX 1003.2 special builtins fails, and
- only for certain failures, as enumerated in the POSIX 1003.2
- standard.
+ script only if one of the POSIX special builtins fails, and only
+ for certain failures, as enumerated in the POSIX standard.
* The SVR4.2 shell behaves differently when invoked as `jsh' (it
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: GNU Free Documentation License, Next: Indexes, Prev: Major Differences From The Bourne Shell, Up: Top
+
+Appendix C GNU Free Documentation License
+*****************************************
+
+ Version 1.2, November 2002
+
+ Copyright (C) 2000,2001,2002 Free Software Foundation, Inc.
+ 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, 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 in 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.
+
+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: Indexes, Prev: GNU Free Documentation License, Up: Top
+
+Appendix D Indexes
+******************
+
+* Menu:
+
+* Builtin Index:: Index of Bash builtin commands.
+* Reserved Word Index:: Index of Bash reserved words.
+* Variable Index:: Quick reference helps you find the
+ variable you want.
+* Function Index:: Index of bindable Readline functions.
+* Concept Index:: General index for concepts described in
+ this manual.
+
+\1f
+File: bashref.info, Node: Builtin Index, Next: Reserved Word Index, Up: Indexes
-Index of Shell Builtin Commands
-*******************************
+D.1 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 213)
+* 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 98)
+* caller: Bash Builtins. (line 106)
* cd: Bourne Shell Builtins.
-* command: Bash Builtins.
+ (line 36)
+* command: Bash Builtins. (line 123)
* compgen: Programmable Completion Builtins.
+ (line 10)
* complete: Programmable Completion Builtins.
+ (line 28)
+* compopt: Programmable Completion Builtins.
+ (line 213)
* continue: Bourne Shell Builtins.
-* declare: Bash Builtins.
+ (line 55)
+* declare: Bash Builtins. (line 142)
* dirs: Directory Stack Builtins.
+ (line 7)
* disown: Job Control Builtins.
-* echo: Bash Builtins.
-* enable: Bash Builtins.
+ (line 83)
+* echo: Bash Builtins. (line 221)
+* enable: Bash Builtins. (line 273)
* 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 301)
* 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 321)
+* local: Bash Builtins. (line 328)
+* logout: Bash Builtins. (line 338)
+* mapfile: Bash Builtins. (line 342)
* popd: Directory Stack Builtins.
-* printf: Bash Builtins.
+ (line 37)
+* printf: Bash Builtins. (line 383)
* pushd: Directory Stack Builtins.
+ (line 58)
* pwd: Bourne Shell Builtins.
-* read: Bash Builtins.
+ (line 163)
+* read: Bash Builtins. (line 408)
* readonly: Bourne Shell Builtins.
+ (line 172)
* return: Bourne Shell Builtins.
-* set: The Set Builtin.
+ (line 188)
+* set: The Set Builtin. (line 11)
* shift: Bourne Shell Builtins.
-* shopt: Bash Builtins.
-* source: Bash Builtins.
+ (line 201)
+* shopt: The Shopt Builtin. (line 9)
+* source: Bash Builtins. (line 480)
* suspend: Job Control Builtins.
+ (line 94)
* test: Bourne Shell Builtins.
+ (line 213)
* times: Bourne Shell Builtins.
+ (line 281)
* trap: Bourne Shell Builtins.
-* type: Bash Builtins.
-* typeset: Bash Builtins.
-* ulimit: Bash Builtins.
+ (line 286)
+* type: Bash Builtins. (line 484)
+* typeset: Bash Builtins. (line 515)
+* ulimit: Bash Builtins. (line 521)
* umask: Bourne Shell Builtins.
-* unalias: Bash Builtins.
+ (line 327)
+* unalias: Bash Builtins. (line 607)
* unset: Bourne Shell Builtins.
+ (line 344)
* wait: Job Control Builtins.
+ (line 73)
\1f
-File: bashref.info, Node: Reserved Word Index, Next: Variable Index, Prev: Builtin Index, Up: Top
+File: bashref.info, Node: Reserved Word Index, Next: Variable Index, Prev: Builtin Index, Up: Indexes
-Index of Shell Reserved Words
-*****************************
+D.2 Index of Shell Reserved Words
+=================================
+\0\b[index\0\b]
* Menu:
-* !: Pipelines.
+* !: Pipelines. (line 9)
* [[: Conditional Constructs.
+ (line 117)
* ]]: Conditional Constructs.
+ (line 117)
* 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 76)
* then: Conditional Constructs.
-* time: Pipelines.
-* until: Looping Constructs.
-* while: Looping Constructs.
-* {: Command Grouping.
-* }: Command Grouping.
+ (line 7)
+* time: Pipelines. (line 9)
+* 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
+File: bashref.info, Node: Variable Index, Next: Function Index, Prev: Reserved Word Index, Up: Indexes
-Parameter and Variable Index
-****************************
+D.3 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 46)
+* #: Special Parameters. (line 30)
+* $: Special Parameters. (line 42)
+* *: Special Parameters. (line 9)
+* -: Special Parameters. (line 37)
+* 0: Special Parameters. (line 50)
+* ?: Special Parameters. (line 33)
+* @: Special Parameters. (line 19)
+* _: Special Parameters. (line 59)
* 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_ALIASES: Bash Variables. (line 21)
+* BASH_ARGC: Bash Variables. (line 28)
+* BASH_ARGV: Bash Variables. (line 38)
+* BASH_CMDS: Bash Variables. (line 48)
+* BASH_COMMAND: Bash Variables. (line 55)
+* BASH_ENV: Bash Variables. (line 60)
+* BASH_EXECUTION_STRING: Bash Variables. (line 66)
+* BASH_LINENO: Bash Variables. (line 69)
+* BASH_REMATCH: Bash Variables. (line 78)
+* BASH_SOURCE: Bash Variables. (line 86)
+* BASH_SUBSHELL: Bash Variables. (line 90)
+* BASH_VERSINFO: Bash Variables. (line 94)
+* BASH_VERSION: Bash Variables. (line 118)
+* BASHPID: Bash Variables. (line 16)
* bell-style: Readline Init File Syntax.
+ (line 38)
+* bind-tty-special-chars: Readline Init File Syntax.
+ (line 45)
* CDPATH: Bourne Shell Variables.
-* COLUMNS: Bash Variables.
+ (line 9)
+* COLUMNS: Bash Variables. (line 121)
* comment-begin: Readline Init File Syntax.
-* COMP_CWORD: Bash Variables.
-* COMP_LINE: Bash Variables.
-* COMP_POINT: Bash Variables.
-* COMP_WORDS: Bash Variables.
+ (line 50)
+* COMP_CWORD: Bash Variables. (line 126)
+* COMP_KEY: Bash Variables. (line 155)
+* COMP_LINE: Bash Variables. (line 132)
+* COMP_POINT: Bash Variables. (line 137)
+* COMP_TYPE: Bash Variables. (line 145)
+* COMP_WORDBREAKS: Bash Variables. (line 159)
+* COMP_WORDS: Bash Variables. (line 165)
+* completion-prefix-display-length: Readline Init File Syntax.
+ (line 60)
* completion-query-items: Readline Init File Syntax.
-* COMPREPLY: Bash Variables.
+ (line 67)
+* COMPREPLY: Bash Variables. (line 172)
* convert-meta: Readline Init File Syntax.
-* DIRSTACK: Bash Variables.
+ (line 77)
+* DIRSTACK: Bash Variables. (line 177)
* disable-completion: Readline Init File Syntax.
+ (line 83)
* editing-mode: Readline Init File Syntax.
+ (line 88)
+* EMACS: Bash Variables. (line 187)
* enable-keypad: Readline Init File Syntax.
-* EUID: Bash Variables.
+ (line 94)
+* EUID: Bash Variables. (line 192)
* 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.
+ (line 99)
+* FCEDIT: Bash Variables. (line 196)
+* FIGNORE: Bash Variables. (line 200)
+* FUNCNAME: Bash Variables. (line 206)
+* GLOBIGNORE: Bash Variables. (line 215)
+* GROUPS: Bash Variables. (line 221)
+* histchars: Bash Variables. (line 227)
+* HISTCMD: Bash Variables. (line 242)
+* HISTCONTROL: Bash Variables. (line 247)
+* HISTFILE: Bash Variables. (line 263)
+* HISTFILESIZE: Bash Variables. (line 267)
+* HISTIGNORE: Bash Variables. (line 275)
* history-preserve-point: Readline Init File Syntax.
-* HISTSIZE: Bash Variables.
+ (line 103)
+* history-size: Readline Init File Syntax.
+ (line 109)
+* HISTSIZE: Bash Variables. (line 294)
+* HISTTIMEFORMAT: Bash Variables. (line 298)
* HOME: Bourne Shell Variables.
+ (line 13)
* horizontal-scroll-mode: Readline Init File Syntax.
-* HOSTFILE: Bash Variables.
-* HOSTNAME: Bash Variables.
-* HOSTTYPE: Bash Variables.
+ (line 114)
+* HOSTFILE: Bash Variables. (line 307)
+* HOSTNAME: Bash Variables. (line 318)
+* HOSTTYPE: Bash Variables. (line 321)
* IFS: Bourne Shell Variables.
-* IGNOREEOF: Bash Variables.
+ (line 18)
+* IGNOREEOF: Bash Variables. (line 324)
* input-meta: Readline Init File Syntax.
-* INPUTRC: Bash Variables.
+ (line 121)
+* INPUTRC: Bash Variables. (line 334)
* isearch-terminators: Readline Init File Syntax.
+ (line 128)
* keymap: Readline Init File Syntax.
-* LANG: Bash Variables.
-* LC_ALL: Bash Variables.
-* LC_COLLATE: Bash Variables.
-* LC_CTYPE: Bash Variables.
-* LC_MESSAGES <1>: Locale Translation.
-* LC_MESSAGES: Bash Variables.
-* LC_NUMERIC: Bash Variables.
-* LINENO: Bash Variables.
-* LINES: Bash Variables.
-* MACHTYPE: Bash Variables.
+ (line 135)
+* LANG: Bash Variables. (line 338)
+* LC_ALL: Bash Variables. (line 342)
+* LC_COLLATE: Bash Variables. (line 346)
+* LC_CTYPE: Bash Variables. (line 353)
+* LC_MESSAGES <1>: Locale Translation. (line 11)
+* LC_MESSAGES: Bash Variables. (line 358)
+* LC_NUMERIC: Bash Variables. (line 362)
+* LINENO: Bash Variables. (line 366)
+* LINES: Bash Variables. (line 370)
+* MACHTYPE: Bash Variables. (line 375)
* MAIL: Bourne Shell Variables.
-* MAILCHECK: Bash Variables.
+ (line 22)
+* MAILCHECK: Bash Variables. (line 379)
* MAILPATH: Bourne Shell Variables.
+ (line 27)
* mark-modified-lines: Readline Init File Syntax.
+ (line 148)
* mark-symlinked-directories: Readline Init File Syntax.
+ (line 153)
* match-hidden-files: Readline Init File Syntax.
+ (line 158)
* meta-flag: Readline Init File Syntax.
-* OLDPWD: Bash Variables.
+ (line 121)
+* OLDPWD: Bash Variables. (line 387)
* OPTARG: Bourne Shell Variables.
-* OPTERR: Bash Variables.
+ (line 34)
+* OPTERR: Bash Variables. (line 390)
* OPTIND: Bourne Shell Variables.
-* OSTYPE: Bash Variables.
+ (line 38)
+* OSTYPE: Bash Variables. (line 394)
* output-meta: Readline Init File Syntax.
+ (line 165)
* page-completions: Readline Init File Syntax.
+ (line 170)
* PATH: Bourne Shell Variables.
-* PIPESTATUS: Bash Variables.
-* POSIXLY_CORRECT: Bash Variables.
-* PPID: Bash Variables.
-* PROMPT_COMMAND: Bash Variables.
+ (line 42)
+* PIPESTATUS: Bash Variables. (line 397)
+* POSIXLY_CORRECT: Bash Variables. (line 402)
+* PPID: Bash Variables. (line 411)
+* PROMPT_COMMAND: Bash Variables. (line 415)
+* PROMPT_DIRTRIM: Bash Variables. (line 419)
* 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 425)
+* PS4: Bash Variables. (line 430)
+* PWD: Bash Variables. (line 436)
+* RANDOM: Bash Variables. (line 439)
+* REPLY: Bash Variables. (line 444)
+* revert-all-at-newline: Readline Init File Syntax.
+ (line 180)
+* SECONDS: Bash Variables. (line 447)
+* SHELL: Bash Variables. (line 453)
+* SHELLOPTS: Bash Variables. (line 458)
+* SHLVL: Bash Variables. (line 467)
* show-all-if-ambiguous: Readline Init File Syntax.
-* TEXTDOMAIN: Locale Translation.
-* TEXTDOMAINDIR: Locale Translation.
-* TIMEFORMAT: Bash Variables.
-* TMOUT: Bash Variables.
-* UID: Bash Variables.
+ (line 186)
+* show-all-if-unmodified: Readline Init File Syntax.
+ (line 192)
+* TEXTDOMAIN: Locale Translation. (line 11)
+* TEXTDOMAINDIR: Locale Translation. (line 11)
+* TIMEFORMAT: Bash Variables. (line 472)
+* TMOUT: Bash Variables. (line 510)
+* TMPDIR: Bash Variables. (line 522)
+* UID: Bash Variables. (line 526)
* visible-stats: Readline Init File Syntax.
+ (line 201)
\1f
-File: bashref.info, Node: Function Index, Next: Concept Index, Prev: Variable Index, Up: Top
+File: bashref.info, Node: Function Index, Next: Concept Index, Prev: Variable Index, Up: Indexes
-Function Index
-**************
+D.4 Function Index
+==================
+\0\b[index\0\b]
* Menu:
* abort (C-g): Miscellaneous Commands.
-* accept-line (Newline or 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.
+ (line 46)
+* clear-screen (C-l): Commands For Moving. (line 34)
* 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 6)
+* copy-backward-word (): Commands For Killing. (line 58)
+* copy-forward-word (): Commands For Killing. (line 63)
+* copy-region-as-kill (): Commands For Killing. (line 54)
+* 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 46)
+* 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 50)
+* 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.
-* overwrite-mode (): Commands For Text.
+ (line 36)
+* overwrite-mode (): Commands For Text. (line 50)
* possible-completions (M-?): Commands For Completion.
+ (line 15)
* prefix-meta (<ESC>): Miscellaneous Commands.
-* previous-history (C-p): Commands For History.
-* quoted-insert (C-q or C-v): Commands For Text.
+ (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 38)
+* 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.
+ (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.
-* 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-. or M-_): Commands For History.
-* yank-nth-arg (M-C-y): Commands For History.
-* yank-pop (M-y): Commands For Killing.
+ (line 22)
+* universal-argument (): Numeric Arguments. (line 10)
+* unix-filename-rubout (): Commands For Killing. (line 41)
+* unix-line-discard (C-u): Commands For Killing. (line 12)
+* unix-word-rubout (C-w): Commands For Killing. (line 37)
+* upcase-word (M-u): Commands For Text. (line 38)
+* yank (C-y): Commands For Killing. (line 68)
+* yank-last-arg (M-. or M-_): Commands For History. (line 65)
+* yank-nth-arg (M-C-y): Commands For History. (line 56)
+* yank-pop (M-y): Commands For Killing. (line 71)
\1f
-File: bashref.info, Node: Concept Index, Prev: Function Index, Up: Top
+File: bashref.info, Node: Concept Index, Prev: Function Index, Up: Indexes
-Concept Index
-*************
+D.5 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 17)
* 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 9)
+* 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 21)
+* coprocess: Coprocesses. (line 6)
+* 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 26)
+* 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)
+* field: Definitions. (line 30)
+* filename: Definitions. (line 35)
+* 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 225)
+* identifier: Definitions. (line 51)
+* initialization file, readline: Readline Init File. (line 6)
+* installation: Basic Installation. (line 6)
* interaction, readline: Readline Interaction.
-* interactive shell <1>: Invoking Bash.
-* interactive shell: Interactive Shells.
-* internationalization: Locale Translation.
-* 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 127)
+* internationalization: Locale Translation. (line 6)
+* job: Definitions. (line 38)
+* job control <1>: Job Control Basics. (line 6)
+* job control: Definitions. (line 42)
* kill ring: Readline Killing Commands.
+ (line 19)
* killing text: Readline Killing Commands.
-* localization: Locale Translation.
-* login shell: Invoking Bash.
-* matching, pattern: Pattern Matching.
-* metacharacter: Definitions.
-* name: Definitions.
-* native languages: Locale Translation.
+ (line 6)
+* localization: Locale Translation. (line 6)
+* login shell: Invoking Bash. (line 124)
+* matching, pattern: Pattern Matching. (line 6)
+* metacharacter: Definitions. (line 46)
+* name: Definitions. (line 51)
+* native languages: Locale Translation. (line 6)
* notation, readline: Readline Bare Essentials.
-* operator, shell: Definitions.
+ (line 6)
+* operator, shell: Definitions. (line 57)
* 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 62)
+* process group ID: Definitions. (line 66)
* 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 70)
* 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.
-* translation, native languages: Locale Translation.
-* variable, shell: Shell Parameters.
+ (line 6)
+* return status: Definitions. (line 75)
+* 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 78)
+* signal handling: Signals. (line 6)
+* special builtin <1>: Special Builtins. (line 6)
+* special builtin: Definitions. (line 82)
+* startup files: Bash Startup Files. (line 6)
+* suspending jobs: Job Control Basics. (line 6)
+* tilde expansion: Tilde Expansion. (line 6)
+* token: Definitions. (line 86)
+* translation, native languages: Locale Translation. (line 6)
+* variable, shell: Shell Parameters. (line 6)
* variables, readline: Readline Init File Syntax.
-* word: Definitions.
-* word splitting: Word Splitting.
+ (line 37)
+* word: Definitions. (line 90)
+* word splitting: Word Splitting. (line 6)
* yanking text: Readline Killing Commands.
+ (line 6)
\1f
Tag Table:
-Node: Top\7f1160
-Node: Introduction\7f3285
-Node: What is Bash?\7f3510
-Node: What is a shell?\7f4611
-Node: Definitions\7f6845
-Node: Basic Shell Features\7f9585
-Node: Shell Syntax\7f10809
-Node: Shell Operation\7f11833
-Node: Quoting\7f13118
-Node: Escape Character\7f14377
-Node: Single Quotes\7f14849
-Node: Double Quotes\7f15184
-Node: ANSI-C Quoting\7f16085
-Node: Locale Translation\7f17028
-Node: Comments\7f17911
-Node: Shell Commands\7f18516
-Node: Simple Commands\7f19397
-Node: Pipelines\7f20018
-Node: Lists\7f21554
-Node: Looping Constructs\7f23177
-Node: Conditional Constructs\7f25621
-Node: Command Grouping\7f31547
-Node: Shell Functions\7f32924
-Node: Shell Parameters\7f35460
-Node: Positional Parameters\7f37034
-Node: Special Parameters\7f37925
-Node: Shell Expansions\7f40583
-Node: Brace Expansion\7f42503
-Node: Tilde Expansion\7f44172
-Node: Shell Parameter Expansion\7f46503
-Node: Command Substitution\7f53303
-Node: Arithmetic Expansion\7f54625
-Node: Process Substitution\7f55469
-Node: Word Splitting\7f56506
-Node: Filename Expansion\7f57958
-Node: Pattern Matching\7f59916
-Node: Quote Removal\7f63140
-Node: Redirections\7f63426
-Node: Executing Commands\7f70900
-Node: Simple Command Expansion\7f71567
-Node: Command Search and Execution\7f73488
-Node: Command Execution Environment\7f75485
-Node: Environment\7f78192
-Node: Exit Status\7f79843
-Node: Signals\7f81038
-Node: Shell Scripts\7f82949
-Node: Shell Builtin Commands\7f85460
-Node: Bourne Shell Builtins\7f86890
-Node: Bash Builtins\7f102594
-Node: The Set Builtin\7f127866
-Node: Special Builtins\7f134847
-Node: Shell Variables\7f135819
-Node: Bourne Shell Variables\7f136255
-Node: Bash Variables\7f138034
-Node: Bash Features\7f154053
-Node: Invoking Bash\7f154935
-Node: Bash Startup Files\7f160399
-Node: Interactive Shells\7f165269
-Node: What is an Interactive Shell?\7f165671
-Node: Is this Shell Interactive?\7f166306
-Node: Interactive Shell Behavior\7f167112
-Node: Bash Conditional Expressions\7f170379
-Node: Shell Arithmetic\7f173798
-Node: Aliases\7f176236
-Node: Arrays\7f178739
-Node: The Directory Stack\7f181759
-Node: Directory Stack Builtins\7f182465
-Node: Printing a Prompt\7f185343
-Node: The Restricted Shell\7f187969
-Node: Bash POSIX Mode\7f189794
-Node: Job Control\7f195965
-Node: Job Control Basics\7f196431
-Node: Job Control Builtins\7f200711
-Node: Job Control Variables\7f205006
-Node: Command Line Editing\7f206155
-Node: Introduction and Notation\7f207153
-Node: Readline Interaction\7f208770
-Node: Readline Bare Essentials\7f209956
-Node: Readline Movement Commands\7f211736
-Node: Readline Killing Commands\7f212692
-Node: Readline Arguments\7f214600
-Node: Searching\7f215635
-Node: Readline Init File\7f217812
-Node: Readline Init File Syntax\7f218866
-Node: Conditional Init Constructs\7f230030
-Node: Sample Init File\7f232554
-Node: Bindable Readline Commands\7f235737
-Node: Commands For Moving\7f236936
-Node: Commands For History\7f237784
-Node: Commands For Text\7f240672
-Node: Commands For Killing\7f243332
-Node: Numeric Arguments\7f245282
-Node: Commands For Completion\7f246409
-Node: Keyboard Macros\7f249989
-Node: Miscellaneous Commands\7f250547
-Node: Readline vi Mode\7f255845
-Node: Programmable Completion\7f256754
-Node: Programmable Completion Builtins\7f262149
-Node: Using History Interactively\7f269370
-Node: Bash History Facilities\7f270049
-Node: Bash History Builtins\7f272609
-Node: History Interaction\7f276175
-Node: Event Designators\7f278726
-Node: Word Designators\7f279653
-Node: Modifiers\7f281282
-Node: Installing Bash\7f282599
-Node: Basic Installation\7f283741
-Node: Compilers and Options\7f286426
-Node: Compiling For Multiple Architectures\7f287160
-Node: Installation Names\7f288817
-Node: Specifying the System Type\7f289628
-Node: Sharing Defaults\7f290337
-Node: Operation Controls\7f291002
-Node: Optional Features\7f291953
-Node: Reporting Bugs\7f299895
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-Node: Function Index\7f326841
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+Node: Specifying the System Type\7f335097
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+Node: Reporting Bugs\7f346846
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+Node: GNU Free Documentation License\7f364727
+Node: Indexes\7f387188
+Node: Builtin Index\7f387642
+Node: Reserved Word Index\7f394396
+Node: Variable Index\7f396844
+Node: Function Index\7f408650
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\1f
End Tag Table
projects / platform / upstream / bash.git / blobdiff