-This is bashref.info, produced by makeinfo version 4.7 from
+This is bashref.info, produced by makeinfo version 4.13 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 (version 3.0, 27 July 2004).
+This text is a brief description of the features that are present in
+the Bash shell (version 4.2, 28 December 2010).
- This is Edition 3.0, last updated 27 July 2004, of `The GNU Bash
-Reference Manual', for `Bash', Version 3.0.
+ This is Edition 4.2, last updated 28 December 2010, of `The GNU Bash
+Reference Manual', for `Bash', Version 4.2.
- Copyright (C) 1988-2004 Free Software Foundation, Inc.
+ Copyright (C) 1988-2010 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
Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License,
- Version 1.1 or any later version published by the Free Software
+ Version 1.3 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)
+ 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."
+ "GNU Free Documentation License".
+
+ (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."
- (a) The FSF's Back-Cover Text is: "You have freedom to copy and
- modify this GNU Manual, like GNU software. Copies published by
- the Free Software Foundation raise funds for GNU development."
INFO-DIR-SECTION Basics
START-INFO-DIR-ENTRY
*************
This text is a brief description of the features that are present in
-the Bash shell (version 3.0, 27 July 2004)..
+the Bash shell (version 4.2, 28 December 2010).
- This is Edition 3.0, last updated 27 July 2004, of `The GNU Bash
-Reference Manual', for `Bash', Version 3.0.
+ This is Edition 4.2, last updated 28 December 2010, of `The GNU Bash
+Reference Manual', for `Bash', Version 4.2.
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.
-
-* Copying This Manual:: Copying this manual.
-
-* 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
* Menu:
* What is Bash?:: A short description of Bash.
-
* What is a shell?:: A brief introduction to shells.
\1f
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,
A Unix shell is both a command interpreter and a programming
language. As a command interpreter, the shell provides the user
interface to the rich set of GNU utilities. The programming language
-features allow these utilitites to be combined. Files containing
+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 to
`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
* 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
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::).
* 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.
+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.
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: `$', ``', `"', `\', or `newline'. Within double quotes,
-backslashes that are followed by one of these characters are removed.
-Backslashes preceding characters without a special meaning are left
-unmodified. A double quote may be quoted within double quotes by
-preceding it with a backslash. When command history is being used, the
-double quote may not be used to quote the history expansion character.
+`\', and, when history expansion is enabled, `!'. The characters `$'
+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::).
backspace
`\e'
+`\E'
an escape character (not ANSI C)
`\f'
`\''
single quote
+`\"'
+ double quote
+
`\NNN'
the eight-bit character whose value is the octal value NNN (one to
three digits)
the eight-bit character whose value is the hexadecimal value HH
(one or two hex digits)
+`\uHHHH'
+ the Unicode (ISO/IEC 10646) character whose value is the
+ hexadecimal value HHHH (one to four hex digits)
+
+`\UHHHHHHHH'
+ the Unicode (ISO/IEC 10646) character whose value is the
+ hexadecimal value HHHHHHHH (one to eight hex digits)
+
`\cX'
a control-X character
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.
commands.
* Lists:: How to execute commands sequentially.
* Compound Commands:: Shell commands for control flow.
+* Coprocesses:: Two-way communication between commands.
+* GNU Parallel:: Running commands in parallel.
\1f
File: bashref.info, Node: Simple Commands, Next: Pipelines, Up: Shell Commands
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
elapsed (wall-clock) time and user and system time consumed by the
command's execution. The `-p' option changes the output format to that
-specified by POSIX. The `TIMEFORMAT' variable may be set to a format
-string that specifies how the timing information should be displayed.
-*Note Bash Variables::, for a description of the available formats.
-The use of `time' as a reserved word permits the timing of shell
-builtins, shell functions, and pipelines. An external `time' command
-cannot time these easily.
+specified by POSIX. When the shell is in POSIX mode (*note Bash POSIX
+Mode::), it does not recognize `time' as a reserved word if the next
+token begins with a `-'. The `TIMEFORMAT' variable may be set to a
+format string that specifies how the timing information should be
+displayed. *Note Bash Variables::, for a description of the available
+formats. The use of `time' as a reserved word permits the timing of
+shell builtins, shell functions, and pipelines. An external `time'
+command cannot time these easily.
+
+ When the shell is in POSIX mode (*note Bash POSIX Mode::), `time'
+may be followed by a newline. In this case, the shell displays the
+total user and system time consumed by the shell and its children. The
+`TIMEFORMAT' variable may be used to specify the format of the time
+information.
If the pipeline is not executed asynchronously (*note Lists::), the
shell waits for all commands in the pipeline to complete.
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: Compound Commands, Prev: Lists, Up: Shell Commands
+File: bashref.info, Node: Compound Commands, Next: Coprocesses, Prev: Lists, Up: Shell Commands
3.2.4 Compound Commands
-----------------------
`for'
The syntax of the `for' command is:
- for NAME [in WORDS ...]; do COMMANDS; done
+ for NAME [ [in [WORDS ...] ] ; ] do COMMANDS; done
Expand WORDS, and execute COMMANDS once for each member in the
resultant list, with NAME bound to the current member. If `in
WORDS' is not present, the `for' command executes the COMMANDS
COMMANDS are executed and the arithmetic expression EXPR3 is
evaluated. If any expression is omitted, it behaves as if it
evaluates to 1. The return value is the exit status of the last
- command in LIST that is executed, or false if any of the
+ command in COMMANDS that is executed, or false if any of the
expressions is invalid.
`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
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
performed. Conditional operators such as `-f' must be unquoted to
be recognized as primaries.
+ When used with `[[', the `<' and `>' operators sort
+ lexicographically using the current locale.
+
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
and matched accordingly (as in regex3)). The return value is 0 if
the string matches the pattern, and 1 otherwise. If the regular
expression is syntactically incorrect, the conditional
- expression's return value is 2. If the shell option `nocaseglob'
- (see the description of `shopt' in *Note Bash Builtins::) is
+ 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. 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.
+ 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:
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, Next: GNU Parallel, 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. NAME must not be supplied if COMMAND is a
+simple command (*note Simple Commands::); otherwise, it is interpreted
+as the first word of the simple command.
+
+ 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: GNU Parallel, Prev: Coprocesses, Up: Shell Commands
+
+3.2.6 GNU Parallel
+------------------
+
+GNU Parallel, as its name suggests, can be used to build and run
+commands in parallel. You may run the same command with different
+arguments, whether they are filenames, usernames, hostnames, or lines
+read from files.
+
+ For a complete description, refer to the GNU Parallel documentation.
+A few examples should provide a brief introduction to its use.
+
+ For example, it is easy to prefix each line in a text file with a
+specified string:
+ cat file | parallel -k echo prefix_string
+ The `-k' option is required to preserve the lines' order.
+
+ Similarly, you can append a specified string to each line in a text
+file:
+ cat file | parallel -k echo {} append_string
+
+ You can use Parallel to move files from the current directory when
+the number of files is too large to process with one `mv' invocation:
+ ls | parallel mv {} destdir
+
+ As you can see, the {} is replaced with each line read from standard
+input. This will run as many `mv' commands as there are files in the
+current directory. You can emulate a parallel `xargs' by adding the
+`-X' option:
+ ls | parallel -X mv {} destdir
+
+ GNU Parallel can replace certain common idioms that operate on lines
+read from a file (in this case, filenames):
+ for x in $(cat list); do
+ do-something1 $x config-$x
+ do-something2 < $x
+ done | process-output
+
+with a more compact syntax reminiscent of lambdas:
+ cat list | parallel "do-something1 {} config-{} ; do-something2 < {}" | process-output
+
+ Parallel provides a built-in mechanism to remove filename
+extensions, which lends itself to batch file transformations or
+renaming:
+ ls *.gz | parallel -j+0 "zcat {} | bzip2 >{.}.bz2 && rm {}"
+ This will recompress all files in the current directory with names
+ending in .gz using bzip2, running one job per CPU (-j+0) in parallel.
+
+ If a command generates output, you may want to preserve the input
+order in the output. For instance, the following command
+ { echo foss.org.my ; echo debian.org; echo freenetproject.org; } | parallel traceroute
+ will display as output the traceroute invocation that finishes
+first. Using the `-k' option, as we saw above
+ { echo foss.org.my ; echo debian.org; echo freenetproject.org; } | parallel -k traceroute
+ will ensure that the output of `traceroute foss.org.my' is displayed
+first.
+
+\1f
File: bashref.info, Node: Shell Functions, Next: Shell Parameters, Prev: Shell Commands, Up: Basic Shell Features
3.3 Shell Functions
no new process is created to interpret them.
Functions are declared using this syntax:
- [ `function' ] NAME () COMPOUND-COMMAND [ REDIRECTIONS ]
+ NAME () COMPOUND-COMMAND [ REDIRECTIONS ]
+ or
+
+ `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,
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
braces that surround the body of the function must be separated from
the body by `blank's or newlines. This is because the braces are
reserved words and are only recognized as such when they are separated
-by whitespace. Also, when using the braces, the LIST must be
-terminated by a semicolon, a `&', or a newline.
+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
positional parameters is updated to reflect the change. Special
parameter `0' is unchanged. The first element of the `FUNCNAME'
variable is set to the name of the function while the function is
-executing. All other aspects of the shell execution environment are
-identical between a function and its caller with the exception that the
-`DEBUG' trap below) is not inherited unless the function has been given
+executing.
+
+ All other aspects of the shell execution environment are identical
+between a function and its caller with these exceptions: 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' trap). *Note Bourne Shell Builtins::,
-for the description of the `trap' builtin.
+functions inherit the `DEBUG' and `RETURN' traps), and the `ERR' trap
+is not inherited unless the `-o errtrace' shell option has been enabled.
+*Note Bourne Shell Builtins::, for the description of the `trap'
+builtin.
+
+ The `FUNCNEST' variable, if set to a numeric value greater than 0,
+defines a maximum function nesting level. Function invocations that
+exceed the limit cause the entire command to abort.
If the builtin command `return' is executed in a function, the
function completes and execution resumes with the next command after
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
+ Functions may be recursive. The `FUNCNEST' variable may be used to
+limit the depth of the function call stack and restrict the number of
+function invocations. By default, no limit is placed on the number of
recursive calls.
\1f
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::).
+(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
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
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 `$@' expand to nothing (i.e.,
+ they are removed).
`#'
Expands to the number of positional parameters in decimal.
invoke Bash, as given by argument zero.
`_'
- (An underscore.) At shell startup, set to the absolute filename
- of the shell or shell script being executed as passed in the
- argument list. Subsequently, expands to the last argument to the
- previous command, after expansion. Also set to the full pathname
- of each command executed and placed in the environment exported to
- that command. When checking mail, this parameter holds the name
- of the mail file.
+ (An underscore.) At shell startup, set to the absolute pathname
+ used to invoke the shell or shell script being executed as passed
+ in the environment or argument list. Subsequently, expands to the
+ last argument to the previous command, after expansion. Also set
+ to the full pathname used to invoke each command executed and
+ placed in the environment exported to that command. When checking
+ mail, this parameter holds the name of the mail file.
\1f
File: bashref.info, Node: Shell Expansions, Next: Redirections, Prev: Shell Parameters, Up: Basic Shell Features
generated. This mechanism is similar to FILENAME EXPANSION (*note
Filename Expansion::), but the file names generated need not exist.
Patterns to be brace expanded take the form of an optional PREAMBLE,
-followed by either a series of comma-separated strings or a sequnce
+followed by either a series of comma-separated strings or a seqeunce
expression between a pair of braces, followed by an optional POSTSCRIPT.
The preamble is prefixed to each string contained within the braces, and
the postscript is then appended to each resulting string, expanding left
bash$ echo a{d,c,b}e
ade ace abe
- A sequence expression takes the form `{X..Y}', where X and Y are
-either integers or single characters. When integers are supplied, the
-expression expands to each number between X and Y, inclusive. When
-characters are supplied, the expression expands to each character
-lexicographically between X and Y, inclusive. Note that both X and Y
-must be of the same type.
+ 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 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:
followed by a character that is not to be interpreted as part of its
name.
- If the first character of PARAMETER is an exclamation point, a level
-of variable indirection is introduced. Bash uses the value of the
-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 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.
+ If the first character of PARAMETER is an exclamation point (!), a
+level of variable indirection is introduced. Bash uses the value of
+the 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 exceptions to this are the
+expansions of ${!PREFIX
+} and ${!NAME[@]} described below. The exclamation point must
+immediately follow the left brace in order to introduce indirection.
In each of the cases below, WORD is subject to tilde expansion,
parameter expansion, command substitution, and arithmetic expansion.
- When not performing substring expansion, Bash tests for a parameter
-that is unset or null; omitting the colon results in a test only for a
-parameter that is unset. Put another way, if the colon is included,
-the operator tests for both existence and that the value is not null;
-if the colon is omitted, the operator tests only for existence.
+ When not performing substring expansion, using the form described
+below, Bash tests for a parameter that is unset or null. Omitting the
+colon results in a test only for a parameter that is unset. Put
+another way, if the colon is included, the operator tests for both
+PARAMETER's existence and that its value is not null; if the colon is
+omitted, the operator tests only for existence.
`${PARAMETER:-WORD}'
If PARAMETER is unset or null, the expansion of WORD is
OFFSET. LENGTH and OFFSET are arithmetic expressions (*note Shell
Arithmetic::). This is referred to as Substring Expansion.
- LENGTH must evaluate to a number greater than or equal to zero.
If OFFSET evaluates to a number less than zero, the value is used
- 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
- `${PARAMETER[OFFSET]}'. Substring indexing is zero-based unless
- the positional parameters are used, in which case the indexing
- starts at 1.
+ as an offset from the end of the value of PARAMETER. If LENGTH
+ evaluates to a number less than zero, and PARAMETER is not `@' and
+ not an indexed or associative array, it is interpreted as an
+ offset from the end of the value of PARAMETER rather than a number
+ of characters, and the expansion is the characters between the two
+ offsets. If PARAMETER is `@', the result is LENGTH positional
+ parameters beginning at OFFSET. If PARAMETER is an indexed array
+ name subscripted by `@' or `*', the result is the LENGTH members
+ of the array beginning with `${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[@]}'
`${!NAME[*]}'
list.
`${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}'
+`${PARAMETER,,PATTERN}'
+ This expansion modifies the case of alphabetic characters in
+ PARAMETER. The PATTERN is expanded to produce a pattern just as in
+ filename expansion. The `^' operator converts lowercase letters
+ matching PATTERN to uppercase; the `,' operator converts matching
+ uppercase letters to lowercase. The `^^' and `,,' expansions
+ convert each matched character in the expanded value; the `^' and
+ `,' expansions match and convert only the first character in the
+ expanded value. If PATTERN is omitted, it is treated like a `?',
+ which matches every character. If PARAMETER is `@' or `*', the
+ case modification operation is applied to each positional
+ parameter in turn, and the expansion is the resultant list. If
+ PARAMETER is an array variable subscripted with `@' or `*', the
+ case modification operation is applied to each member of the array
+ in turn, and the expansion is the resultant list.
+
\1f
File: bashref.info, Node: Command Substitution, Next: Arithmetic Expansion, Prev: Shell Parameter Expansion, Up: Shell Expansions
The shell treats each character of `$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
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
+ When a pattern is used for filename expansion, the character `.' at
the start of a filename or immediately following a slash must be
matched explicitly, unless the shell option `dotglob' is set. When
matching a file name, the slash character must always be matched
explicitly. In other cases, the `.' character is not treated specially.
- See the description of `shopt' in *Note Bash Builtins::, for a
+ See the description of `shopt' in *note The Shopt Builtin::, for a
description of the `nocaseglob', `nullglob', `failglob', and `dotglob'
options.
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.
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.
anywhere within a simple command or may follow a command. Redirections
are processed in the order they appear, from left to right.
+ Each redirection that may be preceded by a file descriptor number
+may instead be preceded by a word of the form {VARNAME}. In this case,
+for each redirection operator except >&- and <&-, the shell will
+allocate a file descriptor greater than 10 and assign it to {VARNAME}.
+If >&- or <&- is preceded by {VARNAME}, the value of VARNAME defines
+the file descriptor to close.
+
In the following descriptions, if the file descriptor number is
omitted, and the first character of the redirection operator is `<',
the redirection refers to the standard input (file descriptor 0). If
(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.
+standard error was made a copy of the 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:
A failure to open or create a file causes the redirection to fail.
+ 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
-----------------------
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:
equivalent to
>WORD 2>&1
-3.6.5 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.
+
+ 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
DELIMITER. This allows here-documents within shell scripts to be
indented in a natural fashion.
-3.6.6 Here Strings
+3.6.7 Here Strings
------------------
A variant of here documents, the format is:
The WORD is expanded and supplied to the command on its standard
input.
-3.6.7 Duplicating File Descriptors
+3.6.8 Duplicating File Descriptors
----------------------------------
The redirection operator
does not expand to one or more digits, the standard output and standard
error are redirected as described previously.
-3.6.8 Moving File Descriptors
+3.6.9 Moving File Descriptors
-----------------------------
The redirection operator
moves the file descriptor DIGIT to file descriptor N, or the
standard output (file descriptor 1) if N is not specified.
-3.6.9 Opening File Descriptors for Reading and Writing
-------------------------------------------------------
+3.6.10 Opening File Descriptors for Reading and Writing
+-------------------------------------------------------
The redirection operator
[N]<>WORD
* 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.
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
* 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::)
are also executed in a subshell environment. Changes made to the
subshell environment cannot affect the shell's execution environment.
+ 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.
+
If a command is followed by a `&' and job control is not active, the
default standard input for the command is the empty file `/dev/null'.
Otherwise, the invoked command inherits the file descriptors of the
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
3.7.5 Exit Status
-----------------
-For the shell's purposes, a command which exits with a zero exit status
-has succeeded. A non-zero exit status indicates failure. This
+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
seemingly counter-intuitive scheme is used so there is one well-defined
way to indicate success and a variety of ways to indicate various
failure modes. When a command terminates on a fatal signal whose
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.
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
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
* 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
Unless otherwise noted, each builtin command documented as accepting
options preceded by `-' accepts `--' to signify the end of the options.
+The `:', `true', `false', and `test' builtins do not accept options and
+do not treat `--' specially. The `exit', `logout', `break',
+`continue', `let', and `shift' builtins accept and process arguments
+beginning with `-' without requiring `--'. Other builtins that accept
+arguments but are not specified as accepting options interpret
+arguments beginning with `-' as invalid options and require `--' to
+prevent this interpretation.
\1f
File: bashref.info, Node: Bourne Shell Builtins, Next: Bash Builtins, Up: Shell Builtin Commands
=========================
The following shell builtin commands are inherited from the Bourne
-Shell. These commands are implemented as specified by the POSIX 1003.2
+Shell. These commands are implemented as specified by the POSIX
standard.
`: (a colon)'
greater than or equal to 1.
`cd'
- cd [-L|-P] [DIRECTORY]
+ cd [-L|[-P [-e]]] [DIRECTORY]
Change the current working directory to DIRECTORY. If DIRECTORY
is not given, the value of the `HOME' shell variable is used. If
the shell variable `CDPATH' exists, it is used as a search path.
If DIRECTORY begins with a slash, `CDPATH' is not used.
The `-P' option means to not follow symbolic links; symbolic links
- are followed by default or with the `-L' option. If DIRECTORY is
+ are followed by default or with the `-L' option. If the `-e'
+ option is supplied with `-P' and the current working directory
+ cannot be successfully determined after a successful directory
+ change, `cd' will return an unsuccessful status. If DIRECTORY is
`-', it is equivalent to `$OLDPWD'.
If a non-empty directory name from `CDPATH' is used, or if `-' is
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.
When the end of options is encountered, `getopts' exits with a
return value greater than zero. `OPTIND' is set to the index of
- the first non-option argument, and `name' is set to `?'.
+ the first non-option argument, and NAME is set to `?'.
`getopts' normally parses the positional parameters, but if more
arguments are given in ARGS, `getopts' parses those instead.
character found.
`hash'
- hash [-'r] [-p FILENAME] [-dt] [NAME]
- Remember the full pathnames of commands specified as NAME
- arguments, so they need not be searched for on subsequent
- invocations. The commands are found by searching through the
- directories listed in `$PATH'. The `-p' option inhibits the path
- search, and FILENAME is used as the location of NAME. The `-r'
- option causes the shell to forget all remembered locations. The
- `-d' option causes the shell to forget the remembered location of
- each NAME. If the `-t' option is supplied, the full pathname to
- which each NAME corresponds is printed. If multiple NAME
- arguments are supplied with `-t' the NAME is printed before the
- hashed full pathname. The `-l' option causes output to be
- displayed in a format that may be reused as input. If no
+ hash [-r] [-p FILENAME] [-dt] [NAME]
+ Each time `hash' is invoked, it remembers the full pathnames of the
+ commands specified as NAME arguments, so they need not be searched
+ for on subsequent invocations. The commands are found by
+ searching through the directories listed in `$PATH'. Any
+ previously-remembered pathname is discarded. The `-p' option
+ inhibits the path search, and FILENAME is used as the location of
+ NAME. The `-r' option causes the shell to forget all remembered
+ locations. The `-d' option causes the shell to forget the
+ remembered location of each NAME. If the `-t' option is supplied,
+ the full pathname to which each NAME corresponds is printed. If
+ multiple NAME arguments are supplied with `-t' the NAME is printed
+ before the hashed full pathname. The `-l' option causes output to
+ be displayed in a format that may be reused as input. If no
arguments are given, or if only `-l' is supplied, information
about remembered commands is printed. The return status is zero
unless a NAME is not found or an invalid option is supplied.
current directory or an invalid option is supplied.
`readonly'
- readonly [-apf] [NAME[=VALUE]] ...
+ 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. 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.
+ 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]
`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. Operator precedence is used when
+ there are five or more arguments.
`! EXPR'
True if EXPR is false.
unary operator, the expression is false.
3 arguments
- If the second argument is one of the binary conditional
+ The following conditions are applied in the order listed. 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
The expression is parsed and evaluated according to precedence
using the rules listed above.
+ When used with `test' or `[', the `<' and `>' operators sort
+ lexicographically using ASCII ordering.
+
`times'
times
Print out the user and system times used by the shell and its
shell input. The `-l' option causes the shell to print a list of
signal names and their corresponding numbers. Each SIGSPEC is
either a signal name or a signal number. Signal names are case
- insensitive and the `SIG' prefix is optional. If a SIGSPEC is `0'
- or `EXIT', ARG is executed when the shell exits. If a SIGSPEC is
- `DEBUG', the command ARG is executed before every simple command,
- `for' command, `case' command, `select' command, every arithmetic
- `for' command, and before the first command executes in a shell
- function. Refer to the description of the `extglob' option to the
- `shopt' builtin (*note Bash Builtins::) for details of its effect
- on the `DEBUG' trap. If a SIGSPEC is `ERR', the command ARG is
- executed whenever a simple command has a non-zero exit status,
- subject to the following conditions. The `ERR' trap is not
- executed if the failed command is part of the command list
- immediately following an `until' or `while' keyword, part of the
- test in an `if' statement, part of a `&&' or `||' list, or if the
- command's return status is being inverted using `!'. These are
- the same conditions obeyed by the `errexit' option. If a SIGSPEC
- is `RETURN', the command ARG is executed each time a shell
- function or a script executed with the `.' or `source' builtins
- finishes executing.
+ 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 `extdebug' option to the `shopt' builtin (*note
+ The Shopt Builtin::) for details of its effect on the `DEBUG' trap.
+ 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.
+
+ 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 following the `if'
+ or `elif' reserved words, 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.
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 subshell or subshell environment when one is
+ created.
The return status is zero unless a SIGSPEC does not specify a
valid signal.
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
4.2 Bash Builtin Commands
=========================
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.
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. If the `extdebug' shell
- option is enabled using `shopt' (*note Bash Builtins::), the
- source file name and line number where the function is defined are
- displayed as well. `-F' implies `-f'. The following options can
- be used to restrict output to variables with the specified
- attributes or to give variables attributes:
+ 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 `-g' option forces variables to be created or modified at the
+ global scope, even when \fBdeclare\fP is executed in a shell
+ function. It is ignored in all other cases.
+
+ 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. If a variable name is followed by =VALUE, the
- value of the variable is set to VALUE.
+ 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, unless the `-g' option is used. 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'
+ `\E'
escape
`\f'
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)
+ `\uHHHH'
+ the Unicode (ISO/IEC 10646) character whose value is the
+ hexadecimal value HHHH (one to four hex digits)
+
+ `\UHHHHHHHH'
+ the Unicode (ISO/IEC 10646) character whose value is the
+ hexadecimal value HHHHHHHH (one to eight 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'
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 the indexed 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 newline 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.
+ When CALLBACK is evaluated, it is supplied the index of the next
+ array element to be assigned and the line to be assigned to that
+ element as additional arguments. CALLBACK is evaluated after the
+ line is read but before the array element is assigned.
+
+ 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, ARRAY is invalid or unassignable, or ARRAY
+ is not an indexed array.
+
`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
- simply copied to standard output, character escape sequences,
- which are converted and copied to the standard output, and format
- 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, (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.
+ control of the FORMAT. The `-v' option causes the output to be
+ assigned to the variable VAR rather than being printed to the
+ standard output.
+
+ The FORMAT is a character string which contains three types of
+ objects: plain characters, which are simply copied to standard
+ output, character escape sequences, which are converted and copied
+ to the standard output, and format specifications, each of which
+ causes printing of the next successive ARGUMENT. In addition to
+ the standard `printf(1)' formats, `printf' interprets the
+ following extensions:
+
+ `%b'
+ causes `printf' to expand backslash escape sequences 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).
+
+ `%q'
+ causes `printf' to output the corresponding ARGUMENT in a
+ format that can be reused as shell input.
+
+ `%(DATEFMT)T'
+ causes `printf' to output the date-time string resulting from
+ using DATEFMT as a format string for `strftime'(3). The
+ corresponding ARGUMENT is an integer representing the number
+ of seconds since the epoch. Two special argument values may
+ be used: -1 represents the current time, and -2 represents
+ the time the shell was invoked.
+
+ Arguments to non-string format specifiers are treated as C
+ language constants, except that a leading plus or minus sign is
+ allowed, and if the leading character is a single or double quote,
+ the value is the ASCII value of the following character.
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] [-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
- waiting for a complete line of input.
+ waiting for a complete line of input, but honor a delimiter
+ if fewer than NCHARS characters are read before the delimiter.
+
+ `-N NCHARS'
+ `read' returns after reading exactly NCHARS characters rather
+ than waiting for a complete line of input, unless EOF is
+ encountered or `read' times out. Delimiter characters
+ encountered in the input are not treated specially and do not
+ cause `read' to return until NCHARS characters are read.
`-p PROMPT'
Display PROMPT, without a trailing newline, before attempting
`-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:
+`readarray'
+ readarray [-n COUNT] [-O ORIGIN] [-s COUNT] [-t] [-u FD] [
+ -C CALLBACK] [-c QUANTUM] [ARRAY]
+ Read lines from the standard input into the indexed array variable
+ ARRAY, or from file descriptor FD if the `-u' option is supplied.
- `-s'
- Enable (set) each OPTNAME.
+ A synonym for `mapfile'.
- `-u'
- Disable (unset) each OPTNAME.
+`source'
+ source FILENAME
+ A synonym for `.' (*note Bourne Shell Builtins::).
- `-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.
+`type'
+ type [-afptP] [NAME ...]
+ For each NAME, indicate how it would be interpreted if used as a
+ command name.
- `-o'
- Restricts the values of OPTNAME to be those defined for the
- `-o' option to the `set' builtin (*note The Set Builtin::).
+ If the `-t' option is used, `type' prints a single word which is
+ one of `alias', `function', `builtin', `file' or `keyword', if
+ NAME is an alias, shell function, shell builtin, disk file, or
+ shell reserved word, respectively. If the NAME is not found, then
+ nothing is printed, and `type' returns a failure status.
- If either `-s' or `-u' is used with no OPTNAME arguments, the
- display is limited to those options which are set or unset,
- respectively.
+ If the `-p' option is used, `type' either returns the name of the
+ disk file that would be executed, or nothing if `-t' would not
+ return `file'.
- Unless otherwise noted, the `shopt' options are disabled (off) by
- default.
+ The `-P' option forces a path search for each NAME, even if `-t'
+ would not return `file'.
- 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.
+ If a command is hashed, `-p' and `-P' print the hashed value, not
+ necessarily the file that appears first in `$PATH'.
- 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.
+ If the `-a' option is used, `type' returns all of the places that
+ contain an executable named FILE. This includes aliases and
+ functions, if and only if the `-p' option is not also used.
- `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.
+ If the `-f' option is used, `type' does not attempt to find shell
+ functions, as with the `command' builtin.
- `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.
+ The return status is zero if all of the NAMES are found, non-zero
+ if any are not found.
- `checkwinsize'
- If set, Bash checks the window size after each command and,
- if necessary, updates the values of `LINES' and `COLUMNS'.
+`typeset'
+ 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.
- `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.
+`ulimit'
+ 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:
+ `-S'
+ Change and report the soft limit associated with a resource.
- `dotglob'
- If set, Bash includes filenames beginning with a `.' in the
- results of filename expansion.
+ `-H'
+ Change and report the hard limit associated with a resource.
- `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.
+ `-a'
+ All current limits are reported.
- `expand_aliases'
- If set, aliases are expanded as described below under Aliases,
- *Note Aliases::. This option is enabled by default for
- interactive shells.
+ `-b'
+ The maximum socket buffer size.
- `extdebug'
- If set, behavior intended for use by debuggers is enabled:
+ `-c'
+ The maximum size of core files created.
- 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.
+ `-d'
+ The maximum size of a process's data segment.
- 2. If the command run by the `DEBUG' trap returns a
- non-zero value, the next command is skipped and not
- executed.
+ `-e'
+ The maximum scheduling priority ("nice").
- 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.
+ `-f'
+ The maximum size of files written by the shell and its
+ children.
- `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.
-
- `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.
-
- `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.
-
-`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.
-
- If the `-t' option is used, `type' prints a single word which is
- one of `alias', `function', `builtin', `file' or `keyword', if
- NAME is an alias, shell function, shell builtin, disk file, or
- shell reserved word, respectively. If the NAME is not found, then
- nothing is printed, and `type' returns a failure status.
-
- If the `-p' option is used, `type' either returns the name of the
- disk file that would be executed, or nothing if `-t' would not
- return `file'.
-
- The `-P' option forces a path search for each NAME, even if `-t'
- would not return `file'.
-
- If a command is hashed, `-p' and `-P' print the hashed value, not
- necessarily the file that appears first in `$PATH'.
-
- If the `-a' option is used, `type' returns all of the places that
- contain an executable named FILE. This includes aliases and
- functions, if and only if the `-p' option is not also used.
-
- If the `-f' option is used, `type' does not attempt to find shell
- functions, as with the `command' builtin.
-
- The return status is zero if any of the NAMES are found, non-zero
- if none are found.
-
-`typeset'
- typeset [-afFrxi] [-p] [NAME[=VALUE] ...]
- 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' 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:
- `-S'
- Change and report the soft limit associated with a resource.
-
- `-H'
- Change and report the hard limit associated with a resource.
-
- `-a'
- All current limits are reported.
-
- `-c'
- The maximum size of core files created.
-
- `-d'
- The maximum size of a process's data segment.
-
- `-f'
- The maximum size of files created by the shell.
+ `-i'
+ The maximum number of pending signals.
`-l'
The maximum size that may be locked into memory.
`-m'
- The maximum resident set size.
+ The maximum resident set size (many systems do not honor this
+ limit).
`-n'
- The maximum number of open file descriptors.
+ The maximum number of open file descriptors (most systems do
+ not allow this value to be set).
`-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.
The maximum number of processes available to a single user.
`-v'
- The maximum amount of virtual memory available to the process.
+ The maximum amount of virtual memory available to the shell,
+ and, on some systems, to its children.
+
+ `-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
-4.3 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-NAME] [ARGUMENT ...]
+ set [+abefhkmnptuvxBCEHPT] [+o OPTION-NAME] [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:
prompt.
`-e'
- Exit immediately if a simple command (*note Simple
- Commands::) exits with a non-zero status, unless the command
- that fails is part of the command list immediately following
- a `while' or `until' keyword, part of the test in an `if'
- statement, part of a `&&' or `||' list, or if the command's
- return status is being inverted using `!'. A trap on `ERR',
+ Exit immediately if a pipeline (*note Pipelines::), which may
+ consist of a single simple command (*note Simple Commands::),
+ a subshell command enclosed in parentheses (*note Command
+ Grouping::), or one of the commands executed as part of a
+ command list enclosed by braces (*note Command Grouping::)
+ returns a non-zero status. The shell does not exit if the
+ command that fails is part of the command list immediately
+ following a `while' or `until' keyword, part of the test in
+ an `if' statement, part of any command executed in a `&&' or
+ `||' list except the command following the final `&&' or `||',
+ any command in a pipeline but the last, or if the command's
+ return status is being inverted with `!'. A trap on `ERR',
if set, is executed before the shell exits.
+ This option applies to the shell environment and each
+ subshell environment separately (*note Command Execution
+ Environment::), and may cause subshells to exit before
+ executing all the commands in the subshell.
+
`-f'
- Disable file name generation (globbing).
+ Disable filename expansion (globbing).
`-h'
Locate and remember (hash) commands as they are looked up for
`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'.
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.
`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
+ inherited from the environment, and the `SHELLOPTS',
+ `BASHOPTS', `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,
Exit after reading and executing one command.
`-u'
- Treat unset variables as an error when performing parameter
+ Treat unset variables and parameters other than the special
+ parameters `@' or `*' as an error when performing parameter
expansion. An error message will be written to the standard
error, and a non-interactive shell will exit.
Print shell input lines as they are read.
`-x'
- Print a trace of simple commands, \fBfor\fP commands,
- \fBcase\fP commands, \fBselect\fP commands, and arithmetic
- \fBfor\fP commands and their arguments or associated word
- lists after they are expanded and before they are executed.
- The value of the `PS4' variable is expanded and the resultant
- value is printed before the command and its expanded
- arguments.
+ 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
/usr/local
`-T'
- If set, any trap on `DEBUG' is inherited by shell functions,
- command substitutions, and commands executed in a subshell
- environment. The `DEBUG' trap is normally not inherited in
- such cases.
+ If 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
+ are set to the ARGUMENTS, even if some of them begin with a
+ `-'.
+
+ `-'
+ Signal the end of options, cause all remaining ARGUMENTS to
+ be assigned to the positional parameters. The `-x' and `-v'
+ options are turned off. If there are no arguments, the
+ positional parameters remain unchanged.
+
+ Using `+' rather than `-' causes these options to be turned off.
+ The options can also be used upon invocation of the shell. The
+ current set of options may be found in `$-'.
+
+ The remaining N ARGUMENTS are positional parameters and are
+ assigned, in order, to `$1', `$2', ... `$N'. The special
+ parameter `#' is set to N.
+
+ The return status is always zero unless an invalid option is
+ supplied.
+
+\1f
+File: bashref.info, Node: The Shopt Builtin, Prev: The Set Builtin, Up: Modifying Shell Behavior
+
+4.3.2 The Shopt Builtin
+-----------------------
+
+This builtin allows you to change additional shell optional behavior.
+
+`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.
+
+ `compat32'
+ If set, Bash changes its behavior to that of version 3.2 with
+ respect to locale-specific string comparison when using the
+ `[[' conditional command's `<' and `>' operators. Bash
+ versions prior to bash-4.0 use ASCII collation and strcmp(3);
+ bash-4.1 and later use the current locale's collation
+ sequence and strcoll(3).
+
+ `compat40'
+ If set, Bash changes its behavior to that of version 4.0 with
+ respect to locale-specific string comparison when using the
+ `[[' conditional command's `<' and `>' operators (see
+ previous item) and the effect of interrupting a command list.
+
+ `compat41'
+ If set, Bash, when in posix mode, treats a single quote in a
+ double-quoted parameter expansion as a special character.
+ The single quotes must match (an even number) and the
+ characters between the single quotes are considered quoted.
+ This is the behavior of POSIX mode through version 4.1. The
+ default Bash behavior remains as in previous versions.
+
+ `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 `ERR' 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
+ filename 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.
+
+ `lastpipe'
+ If set, and job control is not active, the shell runs the
+ last command of a pipeline not executed in the background in
+ the current shell environment.
+
+ `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.
- `--'
- If no arguments follow this option, then the positional
- parameters are unset. Otherwise, the positional parameters
- are set to the ARGUMENTS, even if some of them begin with a
- `-'.
+ `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.
- `-'
- Signal the end of options, cause all remaining ARGUMENTS to
- be assigned to the positional parameters. The `-x' and `-v'
- options are turned off. If there are no arguments, the
- positional parameters remain unchanged.
+ `xpg_echo'
+ If set, the `echo' builtin expands backslash-escape sequences
+ by default.
- Using `+' rather than `-' causes these options to be turned off.
- The options can also be used upon invocation of the shell. The
- current set of options may be found in `$-'.
- The remaining N ARGUMENTS are positional parameters and are
- assigned, in order, to `$1', `$2', ... `$N'. The special
- parameter `#' is set to N.
+ 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 return status is always zero unless an invalid option is
- supplied.
\1f
-File: bashref.info, Node: Special Builtins, Prev: The Set Builtin, Up: Shell Builtin Commands
+File: bashref.info, Node: Special Builtins, Prev: Modifying Shell Behavior, Up: Shell Builtin Commands
4.4 Special Builtins
====================
-For historical reasons, the POSIX 1003.2 standard has classified
-several builtin commands as _special_. When Bash is executing in POSIX
-mode, the special builtins differ from other builtin commands in three
+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
splits words as part of expansion.
`MAIL'
- If this parameter is set to a filename and the `MAILPATH' variable
- is not set, Bash informs the user of the arrival of mail in the
- specified file.
+ If this parameter is set to a filename or directory name and the
+ `MAILPATH' variable is not set, Bash informs the user of the
+ arrival of mail in the specified file or Maildir-format directory.
`MAILPATH'
A colon-separated list of filenames which the shell periodically
`BASH'
The full pathname used to execute the current instance of Bash.
+`BASHOPTS'
+ A colon-separated list of enabled shell options. Each word in the
+ list is a valid argument for the `-s' option to the `shopt'
+ builtin command (*note The Shopt Builtin::). The options
+ appearing in `BASHOPTS' are those reported as `on' by `shopt'. If
+ this variable is in the environment when Bash starts up, each
+ shell option in the list will be enabled before reading any
+ startup files. This variable is readonly.
+
+`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'.
+ 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 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,
`BASH_LINENO'
An array variable whose members are the line numbers in source
- files corresponding to each member of FUNCNAME.
- `${BASH_LINENO[$i]}' is the line number in the source file where
- `${FUNCNAME[$i + 1]}' was called. The corresponding source file
- name is `${BASH_SOURCE[$i + 1]}'. Use `LINENO' to obtain the
- current line number.
+ files where each corresponding member of FUNCNAME was invoked.
+ `${BASH_LINENO[$i]}' is the line number in the source file
+ (`${BASH_SOURCE[$i+1]}') where `${FUNCNAME[$i]}' was called (or
+ `${BASH_LINENO[$i-1]}' if referenced within another shell
+ function). Use `LINENO' to obtain the current line number.
`BASH_REMATCH'
An array variable whose members are assigned by the `=~' binary
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.
+ An array variable whose members are the source filenames where the
+ corresponding shell function names in the `FUNCNAME' array
+ variable are defined. The shell function `${FUNCNAME[$i]}' is
+ defined in the file `${BASH_SOURCE[$i]}' and called from
+ `${BASH_SOURCE[$i+1]}'
`BASH_SUBSHELL'
Incremented by one each time a subshell or subshell environment is
`BASH_VERSION'
The version number of the current instance of Bash.
+`BASH_XTRACEFD'
+ If set to an integer corresponding to a valid file descriptor, Bash
+ will write the trace output generated when `set -x' is enabled to
+ that file descriptor. This allows tracing output to be separated
+ from diagnostic and error messages. The file descriptor is closed
+ when `BASH_XTRACEFD' is unset or assigned a new value. Unsetting
+ `BASH_XTRACEFD' or assigning it the empty string causes the trace
+ output to be sent to the standard error. Note that setting
+ `BASH_XTRACEFD' to 2 (the standard error file descriptor) and then
+ unsetting it will result in the standard error being closed.
+
`COLUMNS'
- Used by the `select' builtin command to determine the terminal
- width when printing selection lists. Automatically set upon
- receipt of a `SIGWINCH'.
+ Used by the `select' command to determine the terminal width when
+ printing selection lists. Automatically set upon receipt of a
+ `SIGWINCH'.
`COMP_CWORD'
An index into `${COMP_WORDS}' of the word containing the current
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'
`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 line is split into words as Readline
+ would split it, using `COMP_WORDBREAKS' as described above. This
+ variable is available only in shell functions invoked by the
+ programmable completion facilities (*note Programmable
+ Completion::).
`COMPREPLY'
An array variable from which Bash reads the possible completions
generated by a shell function invoked by the programmable
completion facility (*note Programmable Completion::).
+`COPROC'
+ An array variable created to hold the file descriptors for output
+ from and input to an unnamed coprocess (*note Coprocesses::).
+
`DIRSTACK'
An array variable containing the current contents of the directory
stack. Directories appear in the stack in the order they are
`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.
+ Emacs shell buffer and disables line editing.
+
+`ENV'
+ Similar to `BASH_ENV'; used when the shell is invoked in POSIX
+ Mode (*note Bash POSIX Mode::).
`EUID'
The numeric effective user id of the current user. This variable
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.
+ bottom-most element (the one with the highest index) 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.
+
+ This variable can be used with `BASH_LINENO' and `BASH_SOURCE'.
+ Each element of `FUNCNAME' has corresponding elements in
+ `BASH_LINENO' and `BASH_SOURCE' to describe the call stack. For
+ instance, `${FUNCNAME[$i]}' was called from the file
+ `${BASH_SOURCE[$i+1]}' at line number `${BASH_LINENO[$i]}'. The
+ `caller' builtin displays the current call stack using this
+ information.
+
+`FUNCNEST'
+ If set to a numeric value greater than 0, defines a maximum
+ function nesting level. Function invocations that exceed this
+ nesting level will cause the current command to abort.
`GLOBIGNORE'
A colon-separated list of patterns defining the set of filenames to
`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
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.
+ 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
list of possible hostname completions may be changed while the
shell is running; the next time hostname completion is attempted
after the value is changed, Bash adds the contents of the new file
- to the existing list. If `HOSTFILE' is set, but has no value,
- Bash attempts to read `/etc/hosts' to obtain the list of possible
- hostname completions. When `HOSTFILE' is unset, the hostname list
- is cleared.
+ to the existing list. If `HOSTFILE' is set, but has no value, or
+ does not name a readable file, Bash attempts to read `/etc/hosts'
+ to obtain the list of possible hostname completions. When
+ `HOSTFILE' is unset, the hostname list is cleared.
`HOSTNAME'
The name of the current host.
executing.
`LINES'
- Used by the `select' builtin command to determine the column length
- for printing selection lists. Automatically set upon receipt of a
+ Used by the `select' command to determine the column length for
+ printing selection lists. Automatically set upon receipt of a
`SIGWINCH'.
`MACHTYPE'
variable is unset, or set to a value that is not a number greater
than or equal to zero, the shell disables mail checking.
+`MAPFILE'
+ An array variable created to hold the text read by the `mapfile'
+ builtin when no variable name is supplied.
+
`OLDPWD'
The previous working directory as set by the `cd' builtin.
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
and 32767 is generated. Assigning a value to this variable seeds
the random number generator.
+`READLINE_LINE'
+ The contents of the Readline line buffer, for use with `bind -x'
+ (*note Bash Builtins::).
+
+`READLINE_POINT'
+ The position of the insertion point in the Readline line buffer,
+ for use with `bind -x' (*note Bash Builtins::).
+
`REPLY'
The default variable for the `read' 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.
bash [long-opt] [-abefhkmnptuvxdBCDHP] [-o OPTION] [-O SHOPT_OPTION] -c STRING [ARGUMENT ...]
bash [long-opt] -s [-abefhkmnptuvxdBCDHP] [-o OPTION] [-O SHOPT_OPTION] [ARGUMENT ...]
- In addition to the single-character shell command-line options
-(*note The Set Builtin::), there are several multi-character options
-that you can use. These options must appear on the command line before
-the single-character options to be recognized.
+ All of the single-character options used with the `set' builtin
+(*note The Set Builtin::) can be used as options when the shell is
+invoked. In addition, there are several multi-character options 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 Bash
- Builtins:: for a description of the `extdebug' option to the
- `shopt' builtin) and shell function tracing (see *Note The Set
- Builtin:: for a description of the `-o functrace' option).
+ starts. Turns on extended debugging mode (see *note The Shopt
+ Builtin:: for a description of the `extdebug' option to the `shopt'
+ builtin).
`--dump-po-strings'
A list of all double-quoted strings preceded by `$' is printed on
- the standard ouput in the GNU `gettext' PO (portable object) file
+ the standard output in the GNU `gettext' PO (portable object) file
format. Equivalent to `-D' except for the output format.
`--dump-strings'
Equivalent to `-D'.
`--help'
- Display a usage message on standard output and exit sucessfully.
+ Display a usage message on standard output and exit successfully.
`--init-file FILENAME'
`--rcfile FILENAME'
`--posix'
Change the behavior of Bash where the default operation differs
- from the POSIX 1003.2 standard to match the standard. This is
- intended to make Bash behave as a strict superset of that
- standard. *Note Bash POSIX Mode::, for a description of the Bash
- POSIX mode.
+ from the POSIX standard to match the standard. This is intended
+ to make Bash behave as a strict superset of that standard. *Note
+ Bash POSIX Mode::, for a description of the Bash POSIX mode.
`--restricted'
Make the shell a restricted shell (*note The Restricted Shell::).
`-i'
Force the shell to run interactively. Interactive shells are
- described in *Note Interactive Shells::.
+ described in *note Interactive Shells::.
`-l'
Make this shell act as if it had been directly invoked by login.
`-D'
A list of all double-quoted strings preceded by `$' 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
6.2 Bash Startup Files
======================
-This section describs how Bash executes its startup files. If any of
+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'
........................................................
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 network connection, as when executed 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.
+the `SHELLOPTS', `BASHOPTS', `CDPATH', and `GLOBIGNORE' variables, if
+they appear in the environment, are 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
-----------------------------------
An interactive shell is one started without non-option arguments,
-unless `-s' is specified, without specifiying 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.
+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
terminal.
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
`/dev/stdin', `/dev/stdout', or `/dev/stderr', file descriptor 0, 1, or
2, respectively, is checked.
+ When used with `[[', the `<' and `>' operators sort
+lexicographically using the current locale. The `test' command uses
+ASCII ordering.
+
+ 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.
`-x FILE'
True if FILE exists and is executable.
-`-O FILE'
- True if FILE exists and is owned by the effective user id.
-
`-G FILE'
True if FILE exists and is owned by the effective group id.
`-L FILE'
True if FILE exists and is a symbolic link.
+`-N FILE'
+ True if FILE exists and has been modified since it was last read.
+
+`-O FILE'
+ True if FILE exists and is owned by the effective user id.
+
`-S FILE'
True if FILE exists and is a socket.
-`-N FILE'
- True if FILE exists and has been modified since it was last read.
+`FILE1 -ef FILE2'
+ True if FILE1 and FILE2 refer to the same device and inode numbers.
`FILE1 -nt FILE2'
True if FILE1 is newer (according to modification date) than
True if FILE1 is older than FILE2, or if FILE2 exists and FILE1
does not.
-`FILE1 -ef FILE2'
- True if FILE1 and FILE2 refer to the same device and inode numbers.
-
`-o OPTNAME'
- True if shell option OPTNAME is enabled. The list of options
+ True if the shell option OPTNAME is enabled. The list of options
appears in the description of the `-o' option to the `set' builtin
(*note The Set Builtin::).
+`-v VARNAME'
+ True if the shell variable VARNAME is set (has been assigned a
+ value).
+
`-z STRING'
True if the length of STRING is zero.
True if the length of STRING is non-zero.
`STRING1 == STRING2'
- True if the strings are equal. `=' may be used in place of `=='
- for strict POSIX compliance.
+`STRING1 = STRING2'
+ True if the strings are equal. `=' should be used with the `test'
+ command for POSIX conformance.
`STRING1 != STRING2'
True if the strings are not equal.
`STRING1 < STRING2'
- True if STRING1 sorts before STRING2 lexicographically in the
- current locale.
+ True if STRING1 sorts before STRING2 lexicographically.
`STRING1 > STRING2'
- True if STRING1 sorts after STRING2 lexicographically in the
- current locale.
+ True if STRING1 sorts after STRING2 lexicographically.
`ARG1 OP ARG2'
`OP' is one of `-eq', `-ne', `-lt', `-le', `-gt', or `-ge'. These
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.
+its INTEGER attribute turned on to be used in an expression.
Constants with a leading 0 are interpreted as octal numbers. A
leading `0x' or `0X' denotes hexadecimal. Otherwise, numbers take the
-form [BASE`#']N, where BASE is a decimal number between 2 and 64
-representing the arithmetic base, and N is a number in that base. If
-BASE`#' is omitted, then base 10 is used. The digits greater than 9
-are represented by the lowercase letters, the uppercase letters, `@',
-and `_', in that order. If BASE is less than or equal to 36, lowercase
-and uppercase letters may be used interchangably to represent numbers
-between 10 and 35.
+form [BASE`#']N, where the optional BASE is a decimal number between 2
+and 64 representing the arithmetic base, and N is a number in that
+base. If BASE`#' is omitted, then base 10 is used. The digits greater
+than 9 are represented by the lowercase letters, the uppercase letters,
+`@', and `_', in that order. If BASE is less than or equal to 36,
+lowercase and uppercase letters may be used interchangeably to
+represent numbers between 10 and 35.
Operators are evaluated in order of precedence. Sub-expressions in
parentheses are evaluated first and may override the precedence rules
(*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
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
+to a number. If SUBSCRIPT evaluates to a number less than zero, it is
+used as an offset from one greater than the array's maximum index (so a
+subcript of -1 refers to the last element of the array). To explicitly
+declare an array, use
declare -a NAME
The syntax
declare -a NAME[SUBSCRIPT]
- 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.
+ is also accepted; the SUBSCRIPT is ignored.
+
+ 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. 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.
+ 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.
+
+ 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.
+
+ An array variable is considered set if a subscript has been assigned
+a value. The null string is a valid value.
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
+expansion. `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
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.
`\w'
The current working directory, with `$HOME' abbreviated with a
- tilde.
+ tilde (uses the `$PROMPT_DIRTRIM' variable).
`\W'
The basename of `$PWD', with `$HOME' abbreviated with a tilde.
Starting Bash with the `--posix' command-line option or executing `set
-o posix' while Bash is running will cause Bash to conform more closely
-to the POSIX 1003.2 standard by changing the behavior to match that
-specified by POSIX in areas where the Bash default differs.
+to the POSIX standard by changing the behavior to match that specified
+by POSIX in areas where the Bash default differs.
When invoked as `sh', Bash enters POSIX mode after reading the
startup files.
is stopped is `Stopped(SIGNAME)', where SIGNAME is, for example,
`SIGTSTP'.
- 4. Reserved words may not be aliased.
+ 4. The `bg' builtin uses the required format to describe each job
+ placed in the background, which does not include an indication of
+ whether the job is the current or previous job.
+
+ 5. Reserved words appearing in a context where reserved words are
+ recognized do not undergo alias expansion.
- 5. The POSIX 1003.2 `PS1' and `PS2' expansions of `!' to the history
- number and `!!' to `!' are enabled, and parameter expansion is
- performed on the values of `PS1' and `PS2' regardless of the
- setting of the `promptvars' option.
+ 6. The POSIX `PS1' and `PS2' expansions of `!' to the history number
+ and `!!' to `!' are enabled, and parameter expansion is performed
+ on the values of `PS1' and `PS2' regardless of the setting of the
+ `promptvars' option.
- 6. The POSIX 1003.2 startup files are executed (`$ENV') rather than
- the normal Bash files.
+ 7. The POSIX startup files are executed (`$ENV') rather than the
+ normal Bash files.
- 7. Tilde expansion is only performed on assignments preceding a
+ 8. Tilde expansion is only performed on assignments preceding a
command name, rather than on all assignment statements on the line.
- 8. The default history file is `~/.sh_history' (this is the default
+ 9. The default history file is `~/.sh_history' (this is the default
value of `$HISTFILE').
- 9. The output of `kill -l' prints all the signal names on a single
+ 10. The output of `kill -l' prints all the signal names on a single
line, separated by spaces, without the `SIG' prefix.
- 10. The `kill' builtin does not accept signal names with a `SIG'
+ 11. The `kill' builtin does not accept signal names with a `SIG'
prefix.
- 11. Non-interactive shells exit if FILENAME in `.' FILENAME is not
+ 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. Non-interactive shells exit if there is a syntax error in a script
+ read with the `.' or `source' builtins, or in a string processed by
+ the `eval' builtin.
+
+ 15. 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
+ 16. 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
+ 17. 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.
+ 18. POSIX special builtins are found before shell functions during
+ command lookup.
+
+ 19. The `time' reserved word may be used by itself as a command. When
+ used in this way, it displays timing statistics for the shell and
+ its completed children. The `TIMEFORMAT' variable controls the
+ format of the timing information.
+
+ 20. When parsing and expanding a ${...} expansion that appears within
+ double quotes, single quotes are no longer special and cannot be
+ used to quote a closing brace or other special character, unless
+ the operator is one of those defined to perform pattern removal.
+ In this case, they do not have to appear as matched pairs.
+
+ 21. The parser does not recognize `time' as a reserved word if the next
+ token begins with a `-'.
- 17. If a POSIX 1003.2 special builtin returns an error status, a
+ 22. If a POSIX special builtin returns an error status, a
non-interactive shell exits. The fatal errors are those listed in
- the POSIX.2 standard, and include things like passing incorrect
+ the POSIX standard, and include things like passing incorrect
options, redirection errors, variable assignment errors for
assignments preceding the command name, and so on.
- 18. If the `cd' builtin finds a directory to change to using
- `$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
- `$CDPATH', even if the a directory with the same name as the name
- given as an argument to `cd' exists in the current directory.
-
- 20. A non-interactive shell exits with an error status if a variable
+ 23. A non-interactive shell exits with an error status if a variable
assignment error occurs when no command name follows the assignment
statements. A variable assignment error occurs, for example, when
trying to assign a value to a readonly variable.
- 21. A non-interactive shell exits with an error status if the iteration
+ 24. A non-interactive shell exists with an error status if a variable
+ assignment error occurs in an assignment statement preceding a
+ special builtin, but not with any other simple command.
+
+ 25. A non-interactive shell exits with an error status if the iteration
variable in a `for' statement or the selection variable in a
`select' statement is a readonly variable.
- 22. Process substitution is not available.
+ 26. Process substitution is not available.
- 23. Assignment statements preceding POSIX 1003.2 special builtins
- persist in the shell environment after the builtin completes.
+ 27. 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
+ 28. 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.
+ 29. The `export' and `readonly' builtin commands display their output
+ in the format required by POSIX.
- 26. The `trap' builtin displays signal names without the leading `SIG'.
+ 30. The `trap' builtin displays signal names without the leading `SIG'.
- 27. The `trap' builtin doesn't check the first argument for a possible
+ 31. The `trap' builtin doesn't check the first argument for a possible
signal specification and revert the signal handling to the original
- disposition if it is. If users want to reset the handler for a
- given signal to the original disposition, they should use `-' as
- the first argument.
+ 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
+ 32. The `.' and `source' builtins do not search the current directory
for the filename argument if it is not found by searching `PATH'.
- 29. Subshells spawned to execute command substitutions inherit the
+ 33. Subshells spawned to execute command substitutions inherit the
value of the `-e' option from the parent shell. When not in POSIX
mode, Bash clears the `-e' option in such subshells.
- 30. Alias expansion is always enabled, even in non-interactive shells.
+ 34. Alias expansion is always enabled, even in non-interactive shells.
- 31. When the `alias' builtin displays alias definitions, it does not
+ 35. When the `alias' builtin displays alias definitions, it does not
display them with a leading `alias ' unless the `-p' option is
supplied.
- 32. When the `set' builtin is invoked without options, it does not
+ 36. When the `set' builtin is invoked without options, it does not
display shell function names and definitions.
- 33. When the `set' builtin is invoked without options, it displays
+ 37. When the `set' builtin is invoked without options, it displays
variable values without quotes, unless they contain shell
metacharacters, even if the result contains nonprinting characters.
- 34. When the `cd' builtin is invoked in LOGICAL mode, and the pathname
+ 38. 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:
+ 39. 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.
+
+ 40. When listing the history, the `fc' builtin does not include an
+ indication of whether or not a history entry has been modified.
- 1. Assignment statements affect the execution environment of all
- builtins, not just special ones.
+ 41. The default editor used by `fc' is `ed'.
- 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 `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
+ `$PATH'.
- 3. When using `.' to source a shell script found in `$PATH', bash
- checks execute permission bits rather than read permission bits,
- just as if it were searching for a command.
+ 43. The `vi' editing mode will invoke the `vi' editor directly when
+ the `v' command is run, instead of checking `$VISUAL' and
+ `$EDITOR'.
+ 44. 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.
+
+ 45. The `ulimit' builtin uses a block size of 512 bytes for the `-c'
+ and `-f' options.
+
+ 46. The arrival of `SIGCHLD' when a trap is set on `SIGCHLD' does not
+ interrupt the `wait' builtin and cause it to return immediately.
+ The trap command is run once for each child that exits.
+
+
+ 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
7 Job Control
*************
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.
+interface supplied jointly by the operating system kernel's terminal
+driver and Bash.
The shell associates a JOB with each pipeline. It keeps a table of
currently executing jobs, which may be listed with the `jobs' command.
are said to be in the foreground. Background processes are those whose
process group ID differs from the terminal's; such processes are immune
to keyboard-generated signals. Only foreground processes are allowed
-to read from or write to the terminal. Background processes which
-attempt to read from (write to) the terminal are sent a `SIGTTIN'
-(`SIGTTOU') signal by the terminal driver, which, unless caught,
-suspends the process.
+to read from or, if the user so specifies with `stty tostop', write to
+the terminal. Background processes which attempt to read from (write
+to when `stty tostop' is in effect) the terminal are sent a `SIGTTIN'
+(`SIGTTOU') signal by the kernel's terminal driver, which, unless
+caught, suspends the process.
If the operating system on which Bash is running supports job
control, Bash contains facilities to use it. Typing the SUSPEND
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 made 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
========================
`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]
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
\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
8 Command Line Editing
**********************
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:
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.
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-display-width'
+ The number of screen columns used to display possible matches
+ when performing completion. The value is ignored if it is
+ less than 0 or greater than the terminal screen width. A
+ value of 0 will cause matches to be displayed one per line.
+ The default value is -1.
+
`completion-ignore-case'
If set to `on', Readline performs filename matching and
completion in a case-insensitive fashion. The default value
is `off'.
+ `completion-map-case'
+ If set to `on', and COMPLETION-IGNORE-CASE is enabled,
+ Readline treats hyphens (`-') and underscores (`_') as
+ equivalent when performing case-insensitive filename matching
+ and completion.
+
+ `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 the list of possibilities should be
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'.
+ 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
editing mode, where the keystrokes are most similar to Emacs.
This variable can be set to either `emacs' or `vi'.
+ `echo-control-characters'
+ When set to `on', on operating systems that indicate they
+ support it, readline echoes a character corresponding to a
+ signal generated from the keyboard. The default is `on'.
+
`enable-keypad'
When set to `on', Readline will try to enable the application
keypad when it is called. Some systems need this to enable
the arrow keys. The default is `off'.
+ `enable-meta-key'
+ When set to `on', Readline will try to enable any meta
+ modifier key the terminal claims to support when it is
+ called. On many terminals, the meta key is used to send
+ eight-bit characters. The default is `on'.
+
`expand-tilde'
If set to `on', tilde expansion is performed when Readline
attempts word completion. The default is `off'.
- If set to `on', the history code attempts to place point at
- the same location on each history line retrieved with
- `previous-history' or `next-history'.
+ `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
`match-hidden-files'
This variable, when set to `on', causes Readline to match
files whose names begin with a `.' (hidden files) when
- performing filename completion, unless the leading `.' is
- supplied by the user in the filename to be completed. This
- variable is `on' by default.
+ performing filename completion. If set to `off', the leading
+ `.' must be supplied by the user in the filename to be
+ completed. This variable is `on' by default.
+
+ `menu-complete-display-prefix'
+ If set to `on', menu completion displays the common prefix of
+ the list of possible completions (which may be empty) before
+ cycling through the list. The default is `off'.
`output-meta'
If set to `on', Readline will display characters with the
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
be listed immediately instead of ringing the bell. The
default value is `off'.
+ `skip-completed-text'
+ If set to `on', this alters the default completion behavior
+ when inserting a single match into the line. It's only
+ active when performing completion in the middle of a word.
+ If enabled, readline does not insert characters from the
+ completion that match characters after point in the word
+ being completed, so portions of the word following the cursor
+ are not duplicated. For instance, if this is enabled,
+ attempting completion when the cursor is after the `e' in
+ `Makefile' will result in `Makefile' rather than
+ `Makefilefile', assuming there is a single possible
+ completion. 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.
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).
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.
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.
+ previous history entry). With a numeric argument, behave exactly
+ like `yank-nth-arg'. Successive calls to `yank-last-arg' move
+ back through the history list, inserting the last word (or the
+ word specified by the argument to the first call) of each line in
+ turn. Any numeric argument supplied to these successive calls
+ determines the direction to move through the history. A negative
+ argument switches the direction through the history (back or
+ forward). The history expansion facilities are used to extract
+ the last argument, as if the `!$' history expansion had been
+ specified.
\1f
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'.
+
+`shell-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.
completion is attempted.
`possible-completions (M-?)'
- List the possible completions of the text before point.
+ List the possible completions of the text before point. When
+ displaying completions, Readline sets the number of columns used
+ for display to the value of `completion-display-width', the value
+ of the environment variable `COLUMNS', or the screen width, in
+ that order.
`insert-completions (M-*)'
Insert all completions of the text before point that would have
command is intended to be bound to <TAB>, but is unbound by
default.
+`menu-complete-backward ()'
+ Identical to `menu-complete', but moves backward through the list
+ of possible completions, as if `menu-complete' had been given a
+ negative argument.
+
`delete-char-or-list ()'
Deletes the character under the cursor if not at the beginning or
end of the line (like `delete-char'). If at the end of the line,
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
of that character. A negative count searches for subsequent
occurrences.
+`skip-csi-sequence ()'
+ Read enough characters to consume a multi-key sequence such as
+ those defined for keys like Home and End. Such sequences begin
+ with a Control Sequence Indicator (CSI), usually ESC-[. If this
+ sequence is bound to "\e[", keys producing such sequences will
+ have no effect unless explicitly bound to a readline command,
+ instead of inserting stray characters into the editing buffer.
+ This is unbound by default, but usually bound to ESC-[.
+
`insert-comment (M-#)'
Without a numeric argument, the value of the `comment-begin'
variable is inserted at the beginning of the current line. If a
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.
+The Readline `vi' mode behaves as specified in the POSIX standard.
In order to switch interactively between `emacs' and `vi' editing
modes, use the `set -o emacs' and `set -o vi' commands (*note The Set
First, the command name is identified. If a compspec has been
defined for that command, the compspec is used to generate the list of
-possible completions for the word. If the command word is a full
-pathname, a compspec for the full pathname is searched for first. If
-no compspec is found for the full pathname, an attempt is made to find
-a compspec for the portion following the final slash.
+possible completions for the word. If the command word is the empty
+string (completion attempted at the beginning of an empty line), any
+compspec defined with the `-E' option to `complete' is used. If the
+command word is a full pathname, a compspec for the full pathname is
+searched for first. If no compspec is found for the full pathname, an
+attempt is made to find a compspec for the portion following the final
+slash. If those searches do not result in a compspec, any compspec
+defined with the `-D' option to `complete' is used as the default.
Once a compspec has been found, it is used to generate the list of
matching words. If a compspec is not found, the default Bash completion
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 value of the MARK-DIRECTORIES Readline variable, regardless of the
setting of the MARK-SYMLINKED-DIRECTORIES Readline variable.
+ There is some support for dynamically modifying completions. This is
+most useful when used in combination with a default completion specified
+with `-D'. It's possible for shell functions executed as completion
+handlers to indicate that completion should be retried by returning an
+exit status of 124. If a shell function returns 124, and changes the
+compspec associated with the command on which completion is being
+attempted (supplied as the first argument when the function is
+executed), programmable completion restarts from the beginning, with an
+attempt to find a new compspec for that command. This allows a set of
+completions to be built dynamically as completion is attempted, rather
+than being loaded all at once.
+
+ For instance, assuming that there is a library of compspecs, each
+kept in a file corresponding to the name of the command, the following
+default completion function would load completions dynamically:
+
+ _completion_loader()
+ {
+ . "/etc/bash_completion.d/$1.sh" >/dev/null 2>&1 && return 124
+ }
+ complete -D -F _completion_loader
+
\1f
File: bashref.info, Node: Programmable Completion Builtins, Prev: Programmable Completion, Up: Command Line Editing
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] [-DE] [-A ACTION] [-G GLOBPAT] [-W WORDLIST]
+ [-F FUNCTION] [-C COMMAND] [-X FILTERPAT]
+ [-P PREFIX] [-S SUFFIX] NAME [NAME ...]'
+ `complete -pr [-DE] [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 `-D' option indicates that the
+ remaining options and actions should apply to the "default"
+ command completion; that is, completion attempted on a command for
+ which no completion has previously been defined. 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
- Completion::).
+ Completion::). The `-D' option takes precedence over `-E'.
Other options, if specified, have the following meanings. The
arguments to the `-G', `-W', and `-X' options (and, if necessary,
`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'.
+ 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:
Names of all shell variables. May also be specified as
`-v'.
- `-G GLOBPAT'
- The filename expansion pattern GLOBPAT is expanded to generate
- the possible completions.
-
- `-W WORDLIST'
- The WORDLIST is split using the characters in the `IFS'
- special variable as delimiters, and each resultant word is
- expanded. The possible completions are the members of the
- resultant list which match the word being completed.
-
`-C COMMAND'
COMMAND is executed in a subshell environment, and its output
is used as the possible completions.
environment. When it finishes, the possible completions are
retrieved from the value of the `COMPREPLY' array variable.
- `-X FILTERPAT'
- FILTERPAT is a pattern as used for filename expansion. It is
- applied to the list of possible completions generated by the
- preceding options and arguments, and each completion matching
- FILTERPAT is removed from the list. A leading `!' in
- FILTERPAT negates the pattern; in this case, any completion
- not matching FILTERPAT is removed.
+ `-G GLOBPAT'
+ The filename expansion pattern GLOBPAT is expanded to generate
+ the possible completions.
`-P PREFIX'
PREFIX is added at the beginning of each possible completion
SUFFIX is appended to each possible completion after all
other options have been applied.
+ `-W WORDLIST'
+ The WORDLIST is split using the characters in the `IFS'
+ special variable as delimiters, and each resultant word is
+ expanded. The possible completions are the members of the
+ resultant list which match the word being completed.
+
+ `-X FILTERPAT'
+ FILTERPAT is a pattern as used for filename expansion. It is
+ applied to the list of possible completions generated by the
+ preceding options and arguments, and each completion matching
+ FILTERPAT is removed from the list. A leading `!' in
+ FILTERPAT negates the pattern; in this case, any completion
+ not matching FILTERPAT is removed.
+
The return value is true unless an invalid option is supplied, an
option other than `-p' or `-r' is supplied without a NAME
argument, an attempt is made to remove a completion specification
for a NAME for which no specification exists, or an error occurs
adding a completion specification.
-
+`compopt'
+ `compopt' [-o OPTION] [-DE] [+o OPTION] [NAME]
+ Modify completion options for each NAME according to the OPTIONs,
+ or for the currently-executing 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 `-D'
+ option indicates that the remaining options should apply to the
+ "default" command completion; that is, completion attempted on a
+ command for which no completion has previously been defined. The
+ `-E' option indicates that the remaining options should apply to
+ "empty" command completion; that is, completion attempted on a
+ blank line.
+
+ The `-D' option takes precedence over `-E'.
+
+ 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
9 Using History Interactively
*****************************
performed.
If the `HISTTIMEFORMAT' is set, the time stamp information
-associated with each history entry is written to the history file.
+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
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 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:
-----------------------
An event designator is a reference to a command line entry in the
-history list.
+history list. Unless the reference is absolute, events are relative to
+the current position in the history list.
`!'
Start a history substitution, except when followed by a space, tab,
Refer to the previous command. This is a synonym for `!-1'.
`!STRING'
- Refer to the most recent command starting with STRING.
+ Refer to the most recent command preceding the current position in
+ the history list starting with STRING.
`!?STRING[?]'
- Refer to the most recent command containing STRING. The trailing
- `?' may be omitted if the STRING is followed immediately by a
- newline.
+ Refer to the most recent command preceding the current position in
+ the history list containing STRING. The trailing `?' may be
+ omitted if the STRING is followed immediately by a newline.
`^STRING1^STRING2^'
Quick Substitution. Repeat the last command, replacing STRING1
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
\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
10 Installing Bash
******************
* 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.
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
`=~' 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-extended-glob-default'
+ Set the default value of the EXTGLOB shell option described above
+ under *note The Shopt Builtin:: to be enabled.
`--enable-help-builtin'
Include the `help' builtin, which displays help on shell builtins
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::).
+ Include the `select' compound command, 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.
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. The latest version of Bash is always available for FTP from
-`ftp://ftp.gnu.org/pub/bash/'.
+`ftp://ftp.gnu.org/pub/gnu/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
`bashbug' inserts the first three items automatically into the template
it provides for filing a bug report.
- Please send all reports concerning this manual to <chet@po.CWRU.Edu>.
+ Please send all reports concerning this manual to
+<chet.ramey@case.edu>.
\1f
-File: bashref.info, Node: Major Differences From The Bourne Shell, Next: Copying This Manual, 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
Appendix B Major Differences From The Bourne Shell
**************************************************
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. The Bash history
* 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::).
`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.
+ 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::.
B.1 Implementation Differences From The SVR4.2 Shell
====================================================
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: Copying This Manual, Next: Builtin Index, Prev: Major Differences From The Bourne Shell, Up: Top
-
-Appendix C Copying This Manual
-******************************
-
-* Menu:
-
-* GNU Free Documentation License:: License for copying this manual.
-
-\1f
-File: bashref.info, Node: GNU Free Documentation License, Up: Copying This Manual
+File: bashref.info, Node: GNU Free Documentation License, Next: Indexes, Prev: Major Differences From The Bourne Shell, Up: Top
-C.1 GNU Free Documentation License
-==================================
+Appendix C GNU Free Documentation License
+*****************************************
- Version 1.2, November 2002
+ Version 1.3, 3 November 2008
- Copyright (C) 2000,2001,2002 Free Software Foundation, Inc.
- 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA
+ Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
+ `http://fsf.org/'
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
Page" means the text near the most prominent appearance of the
work's title, preceding the beginning of the body of the text.
+ The "publisher" means any person or entity that distributes copies
+ of the Document to the public.
+
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
a storage or distribution medium, is called an "aggregate" if the
copyright resulting from the compilation is not used to limit the
legal rights of the compilation's users beyond what the individual
- works permit. When the Document is included an aggregate, this
+ 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.
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.
+ except as expressly provided under this License. Any attempt
+ otherwise to copy, modify, sublicense, or distribute it is void,
+ and will automatically terminate your rights under this License.
+
+ However, if you cease all violation of this License, then your
+ license from a particular copyright holder is reinstated (a)
+ provisionally, unless and until the copyright holder explicitly
+ and finally terminates your license, and (b) permanently, if the
+ copyright holder fails to notify you of the violation by some
+ reasonable means prior to 60 days after the cessation.
+
+ Moreover, your license from a particular copyright holder is
+ reinstated permanently if the copyright holder notifies you of the
+ violation by some reasonable means, this is the first time you have
+ received notice of violation of this License (for any work) from
+ that copyright holder, and you cure the violation prior to 30 days
+ after your receipt of the notice.
+
+ Termination of your rights under this section does not terminate
+ the licenses of parties who have received copies or rights from
+ you under this License. If your rights have been terminated and
+ not permanently reinstated, receipt of a copy of some or all of
+ the same material does not give you any rights to use it.
10. FUTURE REVISIONS OF THIS LICENSE
published (not as a draft) by the Free Software Foundation. If
the Document does not specify a version number of this License,
you may choose any version ever published (not as a draft) by the
- Free Software Foundation.
-
-C.1.1 ADDENDUM: How to use this License for your documents
-----------------------------------------------------------
+ Free Software Foundation. If the Document specifies that a proxy
+ can decide which future versions of this License can be used, that
+ proxy's public statement of acceptance of a version permanently
+ authorizes you to choose that version for the Document.
+
+ 11. RELICENSING
+
+ "Massive Multiauthor Collaboration Site" (or "MMC Site") means any
+ World Wide Web server that publishes copyrightable works and also
+ provides prominent facilities for anybody to edit those works. A
+ public wiki that anybody can edit is an example of such a server.
+ A "Massive Multiauthor Collaboration" (or "MMC") contained in the
+ site means any set of copyrightable works thus published on the MMC
+ site.
+
+ "CC-BY-SA" means the Creative Commons Attribution-Share Alike 3.0
+ license published by Creative Commons Corporation, a not-for-profit
+ corporation with a principal place of business in San Francisco,
+ California, as well as future copyleft versions of that license
+ published by that same organization.
+
+ "Incorporate" means to publish or republish a Document, in whole or
+ in part, as part of another Document.
+
+ An MMC is "eligible for relicensing" if it is licensed under this
+ License, and if all works that were first published under this
+ License somewhere other than this MMC, and subsequently
+ incorporated in whole or in part into the MMC, (1) had no cover
+ texts or invariant sections, and (2) were thus incorporated prior
+ to November 1, 2008.
+
+ The operator of an MMC Site may republish an MMC contained in the
+ site under CC-BY-SA on the same site at any time before August 1,
+ 2009, provided the MMC is eligible for relicensing.
+
+
+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
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
+ under the terms of the GNU Free Documentation License, Version 1.3
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
+ 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
permit their use in free software.
\1f
-File: bashref.info, Node: Builtin Index, Next: Reserved Word Index, Prev: Copying This Manual, Up: Top
+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 11)
* [: Bourne Shell Builtins.
- (line 212)
+ (line 217)
* alias: Bash Builtins. (line 11)
* bg: Job Control Builtins.
(line 7)
* bind: Bash Builtins. (line 21)
* break: Bourne Shell Builtins.
(line 29)
-* builtin: Bash Builtins. (line 92)
-* caller: Bash Builtins. (line 100)
+* builtin: Bash Builtins. (line 98)
+* caller: Bash Builtins. (line 106)
* cd: Bourne Shell Builtins.
(line 36)
-* command: Bash Builtins. (line 117)
+* command: Bash Builtins. (line 123)
* compgen: Programmable Completion Builtins.
(line 10)
* complete: Programmable Completion Builtins.
(line 28)
+* compopt: Programmable Completion Builtins.
+ (line 217)
* continue: Bourne Shell Builtins.
- (line 55)
-* declare: Bash Builtins. (line 136)
+ (line 58)
+* declare: Bash Builtins. (line 142)
* dirs: Directory Stack Builtins.
(line 7)
* disown: Job Control Builtins.
(line 83)
-* echo: Bash Builtins. (line 191)
-* enable: Bash Builtins. (line 244)
+* echo: Bash Builtins. (line 226)
+* enable: Bash Builtins. (line 287)
* eval: Bourne Shell Builtins.
- (line 63)
+ (line 66)
* exec: Bourne Shell Builtins.
- (line 70)
+ (line 73)
* exit: Bourne Shell Builtins.
- (line 82)
+ (line 85)
* export: Bourne Shell Builtins.
- (line 88)
+ (line 91)
* fc: Bash History Builtins.
(line 10)
* fg: Job Control Builtins.
(line 16)
* getopts: Bourne Shell Builtins.
- (line 103)
+ (line 106)
* hash: Bourne Shell Builtins.
- (line 145)
-* help: Bash Builtins. (line 272)
+ (line 148)
+* help: Bash Builtins. (line 315)
* history: Bash History Builtins.
(line 39)
* jobs: Job Control Builtins.
(line 25)
* kill: Job Control Builtins.
(line 57)
-* let: Bash Builtins. (line 281)
-* local: Bash Builtins. (line 288)
-* logout: Bash Builtins. (line 298)
+* let: Bash Builtins. (line 335)
+* local: Bash Builtins. (line 342)
+* logout: Bash Builtins. (line 352)
+* mapfile: Bash Builtins. (line 356)
* popd: Directory Stack Builtins.
(line 37)
-* printf: Bash Builtins. (line 302)
+* printf: Bash Builtins. (line 402)
* pushd: Directory Stack Builtins.
(line 58)
* pwd: Bourne Shell Builtins.
- (line 163)
-* read: Bash Builtins. (line 324)
+ (line 167)
+* read: Bash Builtins. (line 447)
+* readarray: Bash Builtins. (line 527)
* readonly: Bourne Shell Builtins.
- (line 172)
+ (line 176)
* return: Bourne Shell Builtins.
- (line 187)
-* set: The Set Builtin. (line 9)
+ (line 192)
+* set: The Set Builtin. (line 11)
* shift: Bourne Shell Builtins.
- (line 200)
-* shopt: Bash Builtins. (line 385)
-* source: Bash Builtins. (line 600)
+ (line 205)
+* shopt: The Shopt Builtin. (line 9)
+* source: Bash Builtins. (line 535)
* suspend: Job Control Builtins.
(line 94)
* test: Bourne Shell Builtins.
- (line 212)
+ (line 217)
* times: Bourne Shell Builtins.
- (line 276)
+ (line 290)
* trap: Bourne Shell Builtins.
- (line 281)
-* type: Bash Builtins. (line 604)
-* typeset: Bash Builtins. (line 635)
-* ulimit: Bash Builtins. (line 641)
+ (line 295)
+* type: Bash Builtins. (line 539)
+* typeset: Bash Builtins. (line 570)
+* ulimit: Bash Builtins. (line 576)
* umask: Bourne Shell Builtins.
- (line 322)
-* unalias: Bash Builtins. (line 703)
+ (line 341)
+* unalias: Bash Builtins. (line 665)
* unset: Bourne Shell Builtins.
- (line 339)
+ (line 358)
* 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. (line 8)
+* !: Pipelines. (line 9)
* [[: Conditional Constructs.
- (line 105)
+ (line 117)
* ]]: Conditional Constructs.
- (line 105)
+ (line 117)
* case: Conditional Constructs.
(line 28)
* do: Looping Constructs. (line 12)
* in: Conditional Constructs.
(line 28)
* select: Conditional Constructs.
- (line 64)
+ (line 76)
* then: Conditional Constructs.
(line 7)
-* time: Pipelines. (line 8)
+* 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. (line 42)
-* #: Special Parameters. (line 26)
-* $: Special Parameters. (line 38)
+* !: Special Parameters. (line 46)
+* #: Special Parameters. (line 30)
+* $: Special Parameters. (line 42)
* *: Special Parameters. (line 9)
-* -: Special Parameters. (line 33)
-* 0: Special Parameters. (line 46)
-* ?: Special Parameters. (line 29)
+* -: Special Parameters. (line 37)
+* 0: Special Parameters. (line 50)
+* ?: Special Parameters. (line 33)
* @: Special Parameters. (line 19)
-* _: Special Parameters. (line 55)
+* _: Special Parameters. (line 59)
* auto_resume: Job Control Variables.
(line 6)
* BASH: Bash Variables. (line 13)
-* BASH_ARGC: Bash Variables. (line 16)
-* BASH_ARGV: Bash Variables. (line 24)
-* BASH_COMMAND: Bash Variables. (line 31)
-* BASH_ENV: Bash Variables. (line 36)
-* BASH_EXECUTION_STRING: Bash Variables. (line 42)
-* BASH_LINENO: Bash Variables. (line 45)
-* BASH_REMATCH: Bash Variables. (line 53)
-* BASH_SOURCE: Bash Variables. (line 61)
-* BASH_SUBSHELL: Bash Variables. (line 65)
-* BASH_VERSINFO: Bash Variables. (line 69)
-* BASH_VERSION: Bash Variables. (line 93)
+* BASH_ALIASES: Bash Variables. (line 30)
+* BASH_ARGC: Bash Variables. (line 37)
+* BASH_ARGV: Bash Variables. (line 47)
+* BASH_CMDS: Bash Variables. (line 57)
+* BASH_COMMAND: Bash Variables. (line 64)
+* BASH_ENV: Bash Variables. (line 69)
+* BASH_EXECUTION_STRING: Bash Variables. (line 75)
+* BASH_LINENO: Bash Variables. (line 78)
+* BASH_REMATCH: Bash Variables. (line 86)
+* BASH_SOURCE: Bash Variables. (line 94)
+* BASH_SUBSHELL: Bash Variables. (line 101)
+* BASH_VERSINFO: Bash Variables. (line 105)
+* BASH_VERSION: Bash Variables. (line 129)
+* BASH_XTRACEFD: Bash Variables. (line 132)
+* BASHOPTS: Bash Variables. (line 16)
+* BASHPID: Bash Variables. (line 25)
* bell-style: Readline Init File Syntax.
- (line 34)
+ (line 38)
+* bind-tty-special-chars: Readline Init File Syntax.
+ (line 45)
* CDPATH: Bourne Shell Variables.
(line 9)
-* COLUMNS: Bash Variables. (line 96)
+* COLUMNS: Bash Variables. (line 143)
* comment-begin: Readline Init File Syntax.
- (line 41)
-* COMP_CWORD: Bash Variables. (line 101)
-* COMP_LINE: Bash Variables. (line 107)
-* COMP_POINT: Bash Variables. (line 112)
-* COMP_WORDBREAKS: Bash Variables. (line 120)
-* COMP_WORDS: Bash Variables. (line 126)
+ (line 50)
+* COMP_CWORD: Bash Variables. (line 148)
+* COMP_KEY: Bash Variables. (line 177)
+* COMP_LINE: Bash Variables. (line 154)
+* COMP_POINT: Bash Variables. (line 159)
+* COMP_TYPE: Bash Variables. (line 167)
+* COMP_WORDBREAKS: Bash Variables. (line 181)
+* COMP_WORDS: Bash Variables. (line 187)
+* completion-display-width: Readline Init File Syntax.
+ (line 55)
+* completion-ignore-case: Readline Init File Syntax.
+ (line 62)
+* completion-map-case: Readline Init File Syntax.
+ (line 67)
+* completion-prefix-display-length: Readline Init File Syntax.
+ (line 73)
* completion-query-items: Readline Init File Syntax.
- (line 51)
-* COMPREPLY: Bash Variables. (line 132)
+ (line 80)
+* COMPREPLY: Bash Variables. (line 195)
* convert-meta: Readline Init File Syntax.
- (line 60)
-* DIRSTACK: Bash Variables. (line 137)
+ (line 90)
+* COPROC: Bash Variables. (line 200)
+* DIRSTACK: Bash Variables. (line 204)
* disable-completion: Readline Init File Syntax.
- (line 66)
+ (line 96)
* editing-mode: Readline Init File Syntax.
- (line 71)
-* EMACS: Bash Variables. (line 147)
+ (line 101)
+* EMACS: Bash Variables. (line 214)
* enable-keypad: Readline Init File Syntax.
- (line 77)
-* EUID: Bash Variables. (line 152)
+ (line 112)
+* ENV: Bash Variables. (line 219)
+* EUID: Bash Variables. (line 223)
* expand-tilde: Readline Init File Syntax.
- (line 82)
-* FCEDIT: Bash Variables. (line 156)
-* FIGNORE: Bash Variables. (line 160)
-* FUNCNAME: Bash Variables. (line 166)
-* GLOBIGNORE: Bash Variables. (line 175)
-* GROUPS: Bash Variables. (line 181)
-* histchars: Bash Variables. (line 187)
-* HISTCMD: Bash Variables. (line 202)
-* HISTCONTROL: Bash Variables. (line 207)
-* HISTFILE: Bash Variables. (line 223)
-* HISTFILESIZE: Bash Variables. (line 227)
-* HISTIGNORE: Bash Variables. (line 234)
+ (line 123)
+* FCEDIT: Bash Variables. (line 227)
+* FIGNORE: Bash Variables. (line 231)
+* FUNCNAME: Bash Variables. (line 237)
+* FUNCNEST: Bash Variables. (line 255)
+* GLOBIGNORE: Bash Variables. (line 260)
+* GROUPS: Bash Variables. (line 266)
+* histchars: Bash Variables. (line 272)
+* HISTCMD: Bash Variables. (line 287)
+* HISTCONTROL: Bash Variables. (line 292)
+* HISTFILE: Bash Variables. (line 308)
+* HISTFILESIZE: Bash Variables. (line 312)
+* HISTIGNORE: Bash Variables. (line 320)
* history-preserve-point: Readline Init File Syntax.
- (line 85)
-* HISTSIZE: Bash Variables. (line 253)
-* HISTTIMEFORMAT: Bash Variables. (line 257)
+ (line 127)
+* history-size: Readline Init File Syntax.
+ (line 133)
+* HISTSIZE: Bash Variables. (line 339)
+* HISTTIMEFORMAT: Bash Variables. (line 343)
* HOME: Bourne Shell Variables.
(line 13)
* horizontal-scroll-mode: Readline Init File Syntax.
- (line 90)
-* HOSTFILE: Bash Variables. (line 264)
-* HOSTNAME: Bash Variables. (line 275)
-* HOSTTYPE: Bash Variables. (line 278)
+ (line 138)
+* HOSTFILE: Bash Variables. (line 352)
+* HOSTNAME: Bash Variables. (line 363)
+* HOSTTYPE: Bash Variables. (line 366)
* IFS: Bourne Shell Variables.
(line 18)
-* IGNOREEOF: Bash Variables. (line 281)
+* IGNOREEOF: Bash Variables. (line 369)
* input-meta: Readline Init File Syntax.
- (line 97)
-* INPUTRC: Bash Variables. (line 291)
+ (line 145)
+* INPUTRC: Bash Variables. (line 379)
* isearch-terminators: Readline Init File Syntax.
- (line 104)
+ (line 152)
* keymap: Readline Init File Syntax.
- (line 111)
-* LANG: Bash Variables. (line 295)
-* LC_ALL: Bash Variables. (line 299)
-* LC_COLLATE: Bash Variables. (line 303)
-* LC_CTYPE: Bash Variables. (line 310)
+ (line 159)
+* LANG: Bash Variables. (line 383)
+* LC_ALL: Bash Variables. (line 387)
+* LC_COLLATE: Bash Variables. (line 391)
+* LC_CTYPE: Bash Variables. (line 398)
* LC_MESSAGES <1>: Locale Translation. (line 11)
-* LC_MESSAGES: Bash Variables. (line 315)
-* LC_NUMERIC: Bash Variables. (line 319)
-* LINENO: Bash Variables. (line 323)
-* LINES: Bash Variables. (line 327)
-* MACHTYPE: Bash Variables. (line 332)
+* LC_MESSAGES: Bash Variables. (line 403)
+* LC_NUMERIC: Bash Variables. (line 407)
+* LINENO: Bash Variables. (line 411)
+* LINES: Bash Variables. (line 415)
+* MACHTYPE: Bash Variables. (line 420)
* MAIL: Bourne Shell Variables.
(line 22)
-* MAILCHECK: Bash Variables. (line 336)
+* MAILCHECK: Bash Variables. (line 424)
* MAILPATH: Bourne Shell Variables.
(line 27)
+* MAPFILE: Bash Variables. (line 432)
* mark-modified-lines: Readline Init File Syntax.
- (line 124)
+ (line 172)
* mark-symlinked-directories: Readline Init File Syntax.
- (line 129)
+ (line 177)
* match-hidden-files: Readline Init File Syntax.
- (line 134)
+ (line 182)
+* menu-complete-display-prefix: Readline Init File Syntax.
+ (line 189)
* meta-flag: Readline Init File Syntax.
- (line 97)
-* OLDPWD: Bash Variables. (line 344)
+ (line 145)
+* OLDPWD: Bash Variables. (line 436)
* OPTARG: Bourne Shell Variables.
(line 34)
-* OPTERR: Bash Variables. (line 347)
+* OPTERR: Bash Variables. (line 439)
* OPTIND: Bourne Shell Variables.
(line 38)
-* OSTYPE: Bash Variables. (line 351)
+* OSTYPE: Bash Variables. (line 443)
* output-meta: Readline Init File Syntax.
- (line 141)
+ (line 194)
* page-completions: Readline Init File Syntax.
- (line 146)
+ (line 199)
* PATH: Bourne Shell Variables.
(line 42)
-* PIPESTATUS: Bash Variables. (line 354)
-* POSIXLY_CORRECT: Bash Variables. (line 359)
-* PPID: Bash Variables. (line 368)
-* PROMPT_COMMAND: Bash Variables. (line 372)
+* PIPESTATUS: Bash Variables. (line 446)
+* POSIXLY_CORRECT: Bash Variables. (line 451)
+* PPID: Bash Variables. (line 460)
+* PROMPT_COMMAND: Bash Variables. (line 464)
+* PROMPT_DIRTRIM: Bash Variables. (line 468)
* PS1: Bourne Shell Variables.
(line 48)
* PS2: Bourne Shell Variables.
(line 53)
-* PS3: Bash Variables. (line 376)
-* PS4: Bash Variables. (line 381)
-* PWD: Bash Variables. (line 387)
-* RANDOM: Bash Variables. (line 390)
-* REPLY: Bash Variables. (line 395)
-* SECONDS: Bash Variables. (line 398)
-* SHELL: Bash Variables. (line 404)
-* SHELLOPTS: Bash Variables. (line 409)
-* SHLVL: Bash Variables. (line 418)
+* PS3: Bash Variables. (line 474)
+* PS4: Bash Variables. (line 479)
+* PWD: Bash Variables. (line 485)
+* RANDOM: Bash Variables. (line 488)
+* READLINE_LINE: Bash Variables. (line 493)
+* READLINE_POINT: Bash Variables. (line 497)
+* REPLY: Bash Variables. (line 501)
+* revert-all-at-newline: Readline Init File Syntax.
+ (line 209)
+* SECONDS: Bash Variables. (line 504)
+* SHELL: Bash Variables. (line 510)
+* SHELLOPTS: Bash Variables. (line 515)
+* SHLVL: Bash Variables. (line 524)
* show-all-if-ambiguous: Readline Init File Syntax.
- (line 156)
+ (line 215)
* show-all-if-unmodified: Readline Init File Syntax.
- (line 162)
+ (line 221)
+* skip-completed-text: Readline Init File Syntax.
+ (line 230)
* TEXTDOMAIN: Locale Translation. (line 11)
* TEXTDOMAINDIR: Locale Translation. (line 11)
-* TIMEFORMAT: Bash Variables. (line 423)
-* TMOUT: Bash Variables. (line 461)
-* UID: Bash Variables. (line 473)
+* TIMEFORMAT: Bash Variables. (line 529)
+* TMOUT: Bash Variables. (line 567)
+* TMPDIR: Bash Variables. (line 579)
+* UID: Bash Variables. (line 583)
* visible-stats: Readline Init File Syntax.
- (line 171)
+ (line 243)
\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:
(line 41)
* character-search-backward (M-C-]): Miscellaneous Commands.
(line 46)
-* clear-screen (C-l): Commands For Moving. (line 26)
+* clear-screen (C-l): Commands For Moving. (line 34)
* complete (<TAB>): Commands For Completion.
(line 6)
-* copy-backward-word (): Commands For Killing. (line 49)
-* copy-forward-word (): Commands For Killing. (line 54)
-* copy-region-as-kill (): Commands For Killing. (line 45)
+* 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.
- (line 34)
-* delete-horizontal-space (): Commands For Killing. (line 37)
+ (line 43)
+* 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.
(line 14)
* downcase-word (M-l): Commands For Text. (line 42)
* dump-functions (): Miscellaneous Commands.
- (line 64)
+ (line 73)
* dump-macros (): Miscellaneous Commands.
- (line 76)
+ (line 85)
* dump-variables (): Miscellaneous Commands.
- (line 70)
+ (line 79)
* 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)
* history-search-backward (): Commands For History. (line 51)
* history-search-forward (): Commands For History. (line 46)
* insert-comment (M-#): Miscellaneous Commands.
- (line 51)
+ (line 60)
* insert-completions (M-*): Commands For Completion.
- (line 18)
+ (line 22)
* kill-line (C-k): Commands For Killing. (line 6)
-* kill-region (): Commands For Killing. (line 41)
+* 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.
- (line 22)
+ (line 26)
+* menu-complete-backward (): Commands For Completion.
+ (line 38)
* next-history (C-n): Commands For History. (line 17)
* non-incremental-forward-search-history (M-n): Commands For History.
(line 41)
* quoted-insert (C-q or C-v): Commands For Text. (line 20)
* re-read-init-file (C-x C-r): Miscellaneous Commands.
(line 6)
-* redraw-current-line (): Commands For Moving. (line 30)
+* redraw-current-line (): Commands For Moving. (line 38)
* reverse-search-history (C-r): Commands For History. (line 27)
* revert-line (M-r): Miscellaneous Commands.
(line 25)
* self-insert (a, b, A, 1, !, ...): Commands For Text. (line 24)
* set-mark (C-@): Miscellaneous Commands.
(line 32)
+* skip-csi-sequence (): Miscellaneous Commands.
+ (line 51)
* start-kbd-macro (C-x (): Keyboard Macros. (line 6)
* transpose-chars (C-t): Commands For Text. (line 27)
* transpose-words (M-t): Commands For Text. (line 33)
* undo (C-_ or C-x C-u): Miscellaneous Commands.
(line 22)
* universal-argument (): Numeric Arguments. (line 10)
-* unix-filename-rubout (): Commands For Killing. (line 32)
+* unix-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 28)
+* 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 59)
-* yank-last-arg (M-. or M-_): Commands For History. (line 63)
+* 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 62)
+* 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:
* Bourne shell: Basic Shell Features.
(line 6)
* brace expansion: Brace Expansion. (line 6)
-* builtin: Definitions. (line 16)
+* builtin: Definitions. (line 17)
* command editing: Readline Bare Essentials.
(line 6)
* command execution: Command Search and Execution.
(line 6)
* command substitution: Command Substitution.
(line 6)
-* command timing: Pipelines. (line 8)
+* command timing: Pipelines. (line 9)
* commands, compound: Compound Commands. (line 6)
* commands, conditional: Conditional Constructs.
(line 6)
* completion builtins: Programmable Completion Builtins.
(line 6)
* configuration: Basic Installation. (line 6)
-* control operator: Definitions. (line 20)
+* control operator: Definitions. (line 21)
+* coprocess: Coprocesses. (line 6)
* directory stack: The Directory Stack. (line 6)
* editing command lines: Readline Bare Essentials.
(line 6)
* execution environment: Command Execution Environment.
(line 6)
* exit status <1>: Exit Status. (line 6)
-* exit status: Definitions. (line 24)
+* exit status: Definitions. (line 26)
* expansion: Shell Expansions. (line 6)
* expansion, arithmetic: Arithmetic Expansion.
(line 6)
* expressions, arithmetic: Shell Arithmetic. (line 6)
* expressions, conditional: Bash Conditional Expressions.
(line 6)
-* FDL, GNU Free Documentation License: GNU Free Documentation License.
- (line 6)
-* field: Definitions. (line 28)
-* filename: Definitions. (line 33)
+* 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.
(line 6)
-* history events: Event Designators. (line 7)
+* history events: Event Designators. (line 8)
* history expansion: History Interaction. (line 6)
* history list: Bash History Facilities.
(line 6)
* History, how to use: Programmable Completion Builtins.
- (line 203)
-* identifier: Definitions. (line 49)
+ (line 237)
+* identifier: Definitions. (line 51)
* initialization file, readline: Readline Init File. (line 6)
* installation: Basic Installation. (line 6)
* interaction, readline: Readline Interaction.
(line 6)
* interactive shell <1>: Interactive Shells. (line 6)
-* interactive shell: Invoking Bash. (line 128)
+* interactive shell: Invoking Bash. (line 127)
* internationalization: Locale Translation. (line 6)
-* job: Definitions. (line 36)
-* job control <1>: Definitions. (line 40)
-* job control: Job Control Basics. (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.
(line 6)
* localization: Locale Translation. (line 6)
-* login shell: Invoking Bash. (line 125)
+* login shell: Invoking Bash. (line 124)
* matching, pattern: Pattern Matching. (line 6)
-* metacharacter: Definitions. (line 44)
-* name: Definitions. (line 49)
+* metacharacter: Definitions. (line 46)
+* name: Definitions. (line 51)
* native languages: Locale Translation. (line 6)
* notation, readline: Readline Bare Essentials.
(line 6)
-* operator, shell: Definitions. (line 55)
+* operator, shell: Definitions. (line 57)
* parameter expansion: Shell Parameter Expansion.
(line 6)
* parameters: Shell Parameters. (line 6)
* pipeline: Pipelines. (line 6)
* POSIX: Definitions. (line 9)
* POSIX Mode: Bash POSIX Mode. (line 6)
-* process group: Definitions. (line 59)
-* process group ID: Definitions. (line 63)
+* process group: Definitions. (line 62)
+* process group ID: Definitions. (line 66)
* process substitution: Process Substitution.
(line 6)
* programmable completion: Programmable Completion.
* Readline, how to use: Job Control Variables.
(line 24)
* redirection: Redirections. (line 6)
-* reserved word: Definitions. (line 67)
+* reserved word: Definitions. (line 70)
* restricted shell: The Restricted Shell.
(line 6)
-* return status: Definitions. (line 72)
+* 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 75)
+* signal: Definitions. (line 78)
* signal handling: Signals. (line 6)
-* special builtin <1>: Definitions. (line 79)
-* special builtin: Special Builtins. (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 83)
+* token: Definitions. (line 86)
* translation, native languages: Locale Translation. (line 6)
* variable, shell: Shell Parameters. (line 6)
* variables, readline: Readline Init File Syntax.
- (line 33)
-* word: Definitions. (line 87)
+ (line 37)
+* word: Definitions. (line 90)
* word splitting: Word Splitting. (line 6)
* yanking text: Readline Killing Commands.
(line 6)
\1f
Tag Table:
-Node: Top\7f1349
-Node: Introduction\7f3485
-Node: What is Bash?\7f3714
-Node: What is a shell?\7f4807
-Node: Definitions\7f7348
-Node: Basic Shell Features\7f10089
-Node: Shell Syntax\7f11308
-Node: Shell Operation\7f12340
-Node: Quoting\7f13634
-Node: Escape Character\7f14908
-Node: Single Quotes\7f15393
-Node: Double Quotes\7f15741
-Node: ANSI-C Quoting\7f16767
-Node: Locale Translation\7f17723
-Node: Comments\7f18619
-Node: Shell Commands\7f19233
-Node: Simple Commands\7f19999
-Node: Pipelines\7f20630
-Node: Lists\7f22505
-Node: Compound Commands\7f24136
-Node: Looping Constructs\7f24920
-Node: Conditional Constructs\7f27367
-Node: Command Grouping\7f34434
-Node: Shell Functions\7f35883
-Node: Shell Parameters\7f40151
-Node: Positional Parameters\7f41732
-Node: Special Parameters\7f42632
-Node: Shell Expansions\7f45299
-Node: Brace Expansion\7f47224
-Node: Tilde Expansion\7f49549
-Node: Shell Parameter Expansion\7f51890
-Node: Command Substitution\7f59153
-Node: Arithmetic Expansion\7f60486
-Node: Process Substitution\7f61336
-Node: Word Splitting\7f62386
-Node: Filename Expansion\7f63847
-Node: Pattern Matching\7f65983
-Node: Quote Removal\7f69316
-Node: Redirections\7f69611
-Node: Executing Commands\7f77190
-Node: Simple Command Expansion\7f77865
-Node: Command Search and Execution\7f79795
-Node: Command Execution Environment\7f81801
-Node: Environment\7f84572
-Node: Exit Status\7f86232
-Node: Signals\7f87436
-Node: Shell Scripts\7f89400
-Node: Shell Builtin Commands\7f91918
-Node: Bourne Shell Builtins\7f93497
-Node: Bash Builtins\7f110450
-Node: The Set Builtin\7f138577
-Node: Special Builtins\7f146800
-Node: Shell Variables\7f147777
-Node: Bourne Shell Variables\7f148217
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-Node: Bash Features\7f169913
-Node: Invoking Bash\7f170796
-Node: Bash Startup Files\7f176615
-Node: Interactive Shells\7f181473
-Node: What is an Interactive Shell?\7f181883
-Node: Is this Shell Interactive?\7f182533
-Node: Interactive Shell Behavior\7f183348
-Node: Bash Conditional Expressions\7f186624
-Node: Shell Arithmetic\7f190049
-Node: Aliases\7f192794
-Node: Arrays\7f195362
-Node: The Directory Stack\7f198393
-Node: Directory Stack Builtins\7f199107
-Node: Printing a Prompt\7f201998
-Node: The Restricted Shell\7f204712
-Node: Bash POSIX Mode\7f206544
-Node: Job Control\7f213197
-Node: Job Control Basics\7f213664
-Node: Job Control Builtins\7f217954
-Node: Job Control Variables\7f222274
-Node: Command Line Editing\7f223432
-Node: Introduction and Notation\7f224431
-Node: Readline Interaction\7f226053
-Node: Readline Bare Essentials\7f227244
-Node: Readline Movement Commands\7f229033
-Node: Readline Killing Commands\7f229998
-Node: Readline Arguments\7f231918
-Node: Searching\7f232962
-Node: Readline Init File\7f235148
-Node: Readline Init File Syntax\7f236207
-Node: Conditional Init Constructs\7f247860
-Node: Sample Init File\7f250393
-Node: Bindable Readline Commands\7f253510
-Node: Commands For Moving\7f254717
-Node: Commands For History\7f255578
-Node: Commands For Text\7f258479
-Node: Commands For Killing\7f261152
-Node: Numeric Arguments\7f263294
-Node: Commands For Completion\7f264433
-Node: Keyboard Macros\7f268026
-Node: Miscellaneous Commands\7f268597
-Node: Readline vi Mode\7f273908
-Node: Programmable Completion\7f274822
-Node: Programmable Completion Builtins\7f280634
-Node: Using History Interactively\7f288004
-Node: Bash History Facilities\7f288684
-Node: Bash History Builtins\7f291379
-Node: History Interaction\7f295236
-Node: Event Designators\7f297792
-Node: Word Designators\7f298807
-Node: Modifiers\7f300446
-Node: Installing Bash\7f301852
-Node: Basic Installation\7f302989
-Node: Compilers and Options\7f305681
-Node: Compiling For Multiple Architectures\7f306422
-Node: Installation Names\7f308086
-Node: Specifying the System Type\7f308904
-Node: Sharing Defaults\7f309620
-Node: Operation Controls\7f310293
-Node: Optional Features\7f311251
-Node: Reporting Bugs\7f319530
-Node: Major Differences From The Bourne Shell\7f320724
-Node: Copying This Manual\7f336496
-Node: GNU Free Documentation License\7f336772
-Node: Builtin Index\7f359178
-Node: Reserved Word Index\7f365727
-Node: Variable Index\7f368163
-Node: Function Index\7f378882
-Node: Concept Index\7f385602
+Node: Top\7f1346
+Node: Introduction\7f3185
+Node: What is Bash?\7f3413
+Node: What is a shell?\7f4526
+Node: Definitions\7f7066
+Node: Basic Shell Features\7f9984
+Node: Shell Syntax\7f11203
+Node: Shell Operation\7f12233
+Node: Quoting\7f13527
+Node: Escape Character\7f14830
+Node: Single Quotes\7f15315
+Node: Double Quotes\7f15663
+Node: ANSI-C Quoting\7f16788
+Node: Locale Translation\7f18032
+Node: Comments\7f18928
+Node: Shell Commands\7f19546
+Node: Simple Commands\7f20418
+Node: Pipelines\7f21049
+Node: Lists\7f23743
+Node: Compound Commands\7f25472
+Node: Looping Constructs\7f26276
+Node: Conditional Constructs\7f28735
+Node: Command Grouping\7f36848
+Node: Coprocesses\7f38327
+Node: GNU Parallel\7f39992
+Node: Shell Functions\7f42460
+Node: Shell Parameters\7f47404
+Node: Positional Parameters\7f49820
+Node: Special Parameters\7f50720
+Node: Shell Expansions\7f53684
+Node: Brace Expansion\7f55609
+Node: Tilde Expansion\7f58364
+Node: Shell Parameter Expansion\7f60715
+Node: Command Substitution\7f69850
+Node: Arithmetic Expansion\7f71183
+Node: Process Substitution\7f72033
+Node: Word Splitting\7f73083
+Node: Filename Expansion\7f74706
+Node: Pattern Matching\7f76845
+Node: Quote Removal\7f80484
+Node: Redirections\7f80779
+Node: Executing Commands\7f89304
+Node: Simple Command Expansion\7f89974
+Node: Command Search and Execution\7f91904
+Node: Command Execution Environment\7f94241
+Node: Environment\7f97227
+Node: Exit Status\7f98887
+Node: Signals\7f100508
+Node: Shell Scripts\7f102476
+Node: Shell Builtin Commands\7f104994
+Node: Bourne Shell Builtins\7f107022
+Node: Bash Builtins\7f124952
+Node: Modifying Shell Behavior\7f151166
+Node: The Set Builtin\7f151511
+Node: The Shopt Builtin\7f161045
+Node: Special Builtins\7f173217
+Node: Shell Variables\7f174196
+Node: Bourne Shell Variables\7f174636
+Node: Bash Variables\7f176663
+Node: Bash Features\7f201572
+Node: Invoking Bash\7f202455
+Node: Bash Startup Files\7f208219
+Node: Interactive Shells\7f213240
+Node: What is an Interactive Shell?\7f213650
+Node: Is this Shell Interactive?\7f214299
+Node: Interactive Shell Behavior\7f215114
+Node: Bash Conditional Expressions\7f218394
+Node: Shell Arithmetic\7f222183
+Node: Aliases\7f224942
+Node: Arrays\7f227514
+Node: The Directory Stack\7f231629
+Node: Directory Stack Builtins\7f232343
+Node: Printing a Prompt\7f235235
+Node: The Restricted Shell\7f237987
+Node: Bash POSIX Mode\7f239819
+Node: Job Control\7f248480
+Node: Job Control Basics\7f248940
+Node: Job Control Builtins\7f253657
+Node: Job Control Variables\7f258021
+Node: Command Line Editing\7f259179
+Node: Introduction and Notation\7f260746
+Node: Readline Interaction\7f262368
+Node: Readline Bare Essentials\7f263559
+Node: Readline Movement Commands\7f265348
+Node: Readline Killing Commands\7f266313
+Node: Readline Arguments\7f268233
+Node: Searching\7f269277
+Node: Readline Init File\7f271463
+Node: Readline Init File Syntax\7f272610
+Node: Conditional Init Constructs\7f287952
+Node: Sample Init File\7f290485
+Node: Bindable Readline Commands\7f293602
+Node: Commands For Moving\7f294809
+Node: Commands For History\7f295953
+Node: Commands For Text\7f299388
+Node: Commands For Killing\7f302061
+Node: Numeric Arguments\7f304518
+Node: Commands For Completion\7f305657
+Node: Keyboard Macros\7f309849
+Node: Miscellaneous Commands\7f310420
+Node: Readline vi Mode\7f316226
+Node: Programmable Completion\7f317133
+Node: Programmable Completion Builtins\7f324343
+Node: Using History Interactively\7f333479
+Node: Bash History Facilities\7f334163
+Node: Bash History Builtins\7f337077
+Node: History Interaction\7f340934
+Node: Event Designators\7f343639
+Node: Word Designators\7f344861
+Node: Modifiers\7f346500
+Node: Installing Bash\7f347904
+Node: Basic Installation\7f349041
+Node: Compilers and Options\7f351733
+Node: Compiling For Multiple Architectures\7f352474
+Node: Installation Names\7f354138
+Node: Specifying the System Type\7f354956
+Node: Sharing Defaults\7f355672
+Node: Operation Controls\7f356345
+Node: Optional Features\7f357303
+Node: Reporting Bugs\7f366871
+Node: Major Differences From The Bourne Shell\7f368072
+Node: GNU Free Documentation License\7f384759
+Node: Indexes\7f409955
+Node: Builtin Index\7f410409
+Node: Reserved Word Index\7f417236
+Node: Variable Index\7f419684
+Node: Function Index\7f432779
+Node: Concept Index\7f439788
\1f
End Tag Table
projects / platform / upstream / bash.git / blobdiff