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576.

Common shell variable names and usage.

BASH_VERSION[tab]Version information for this Bash.
CDPATH[tab]A colon-separated list of directories to search
[tab][tab]for directories given as arguments to `cd'.
GLOBIGNORE[tab]A colon-separated list of patterns describing filenames to
[tab][tab]be ignored by pathname expansion.
HISTFILE[tab]The name of the file where your command history is stored.
HISTFILESIZE[tab]The maximum number of lines this file can contain.
HISTSIZE[tab]The maximum number of history lines that a running
[tab][tab]shell can access.
HOME[tab]The complete pathname to your login directory.
HOSTNAME[tab]The name of the current host.
HOSTTYPE[tab]The type of CPU this version of Bash is running under.
IGNOREEOF[tab]Controls the action of the shell on receipt of an EOF
[tab][tab]character as the sole input. If set, then the value
[tab][tab]of it is the number of EOF characters that can be seen
[tab][tab]in a row on an empty line before the shell will exit
[tab][tab](default 10). When unset, EOF signifies the end of input.
MACHTYPE[tab]A string describing the current system Bash is running on.
MAILCHECK[tab]How often, in seconds, Bash checks for new mail.
MAILPATH[tab]A colon-separated list of filenames which Bash checks
[tab][tab]for new mail.
OSTYPE[tab]The version of Unix this version of Bash is running on.
PATH[tab]A colon-separated list of directories to search when
[tab][tab]looking for commands.
PROMPT_COMMAND[tab]A command to be executed before the printing of each
[tab][tab]primary prompt.
PS1[tab][tab]The primary prompt string.
PS2[tab][tab]The secondary prompt string.
PWD[tab][tab]The full pathname of the current directory.
SHELLOPTS[tab]A colon-separated list of enabled shell options.
TERM[tab]The name of the current terminal type.
TIMEFORMAT[tab]The output format for timing statistics displayed by the
[tab][tab]`time' reserved word.
auto_resume[tab]Non-null means a command word appearing on a line by
[tab][tab]itself is first looked for in the list of currently
[tab][tab]stopped jobs. If found there, that job is foregrounded.
[tab][tab]A value of `exact' means that the command word must
[tab][tab]exactly match a command in the list of stopped jobs. A
[tab][tab]value of `substring' means that the command word must
[tab][tab]match a substring of the job. Any other value means that
[tab][tab]the command must be a prefix of a stopped job.
histchars[tab]Characters controlling history expansion and quick
[tab][tab]substitution. The first character is the history
[tab][tab]substitution character, usually `!'. The second is
[tab][tab]the `quick substitution' character, usually `^'. The
[tab][tab]third is the `history comment' character, usually `#'.
HISTIGNORE[tab]A colon-separated list of patterns used to decide which
[tab][tab]commands should be saved on the history list.

577.

Add directories to stack.

Adds a directory to the top of the directory stack, or rotates
the stack, making the new top of the stack the current working
directory. With no arguments, exchanges the top two directories.

Options:
-n[tab]Suppresses the normal change of directory when adding
[tab][tab]directories to the stack, so only the stack is manipulated.

Arguments:
+N[tab]Rotates the stack so that the Nth directory (counting
[tab][tab]from the left of the list shown by `dirs', starting with
[tab][tab]zero) is at the top.

-N[tab]Rotates the stack so that the Nth directory (counting
[tab][tab]from the right of the list shown by `dirs', starting with
[tab][tab]zero) is at the top.

dir[tab]Adds DIR to the directory stack at the top, making it the
[tab][tab]new current working directory.

The `dirs' builtin displays the directory stack.

Exit Status:
Returns success unless an invalid argument is supplied or the directory
change fails.

578.

Remove directories from stack.

Removes entries from the directory stack. With no arguments, removes
the top directory from the stack, and changes to the new top directory.

Options:
-n[tab]Suppresses the normal change of directory when removing
[tab][tab]directories from the stack, so only the stack is manipulated.

Arguments:
+N[tab]Removes the Nth entry counting from the left of the list
[tab][tab]shown by `dirs', starting with zero. For example: `popd +0'
[tab][tab]removes the first directory, `popd +1' the second.

-N[tab]Removes the Nth entry counting from the right of the list
[tab][tab]shown by `dirs', starting with zero. For example: `popd -0'
[tab][tab]removes the last directory, `popd -1' the next to last.

The `dirs' builtin displays the directory stack.

Exit Status:
Returns success unless an invalid argument is supplied or the directory
change fails.

579.

Display directory stack.

Display the list of currently remembered directories. Directories
find their way onto the list with the `pushd' command; you can get
back up through the list with the `popd' command.

Options:
-c[tab]clear the directory stack by deleting all of the elements
-l[tab]do not print tilde-prefixed versions of directories relative
[tab][tab]to your home directory
-p[tab]print the directory stack with one entry per line
-v[tab]print the directory stack with one entry per line prefixed
[tab][tab]with its position in the stack

Arguments:
+N[tab]Displays the Nth entry counting from the left of the list
[tab][tab]shown by dirs when invoked without options, starting with
[tab][tab]zero.

-N[tab]Displays the Nth entry counting from the right of the list
[tab][tab]shown by dirs when invoked without options, starting with
[tab][tab]zero.

Exit Status:
Returns success unless an invalid option is supplied or an error occurs.

580.

Set and unset shell options.

Change the setting of each shell option OPTNAME. Without any option
arguments, list each supplied OPTNAME, or all shell options if no
OPTNAMEs are given, with an indication of whether or not each is set.

Options:
-o[tab]restrict OPTNAMEs to those defined for use with `set -o'
-p[tab]print each shell option with an indication of its status
-q[tab]suppress output
-s[tab]enable (set) each OPTNAME
-u[tab]disable (unset) each OPTNAME

Exit Status:
Returns success if OPTNAME is enabled; fails if an invalid option is
given or OPTNAME is disabled.

581.

Formats and prints ARGUMENTS under control of the FORMAT.

Options:
-v var[tab]assign the output to shell variable VAR rather than
[tab][tab]display it on the standard output

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 format specifications described in printf(1),
printf interprets:

%b[tab]expand backslash escape sequences in the corresponding argument
%q[tab]quote the argument in a way that can be reused as shell input
%(fmt)T[tab]output the date-time string resulting from using FMT as a format
[tab] string for strftime(3)

The format is re-used as necessary to consume all of the arguments. If
there are fewer arguments than the format requires, extra format
specifications behave as if a zero value or null string, as appropriate,
had been supplied.

Exit Status:
Returns success unless an invalid option is given or a write or assignment
error occurs.

582.

Specify how arguments are to be completed by Readline.

For each NAME, specify how arguments are to be completed. If no options
are supplied, existing completion specifications are printed in a way that
allows them to be reused as input.

Options:
-p[tab]print existing completion specifications in a reusable format
-r[tab]remove a completion specification for each NAME, or, if no
[tab][tab]NAMEs are supplied, all completion specifications
-D[tab]apply the completions and actions as the default for commands
[tab][tab]without any specific completion defined
-E[tab]apply the completions and actions to "empty" commands --
[tab][tab]completion attempted on a blank line
-I[tab]apply the completions and actions to the initial (usually the
[tab][tab]command) word

When completion is attempted, the actions are applied in the order the
uppercase-letter options are listed above. If multiple options are supplied,
the -D option takes precedence over -E, and both take precedence over -I.

Exit Status:
Returns success unless an invalid option is supplied or an error occurs.

583.

Display possible completions depending on the options.

Intended to be used from within a shell function generating possible
completions. If the optional WORD argument is supplied, matches against
WORD are generated.

Exit Status:
Returns success unless an invalid option is supplied or an error occurs.

584.

Modify or display completion options.

Modify the completion options for each NAME, or, if no NAMEs are supplied,
the completion currently being executed. If no OPTIONs are given, print
the completion options for each NAME or the current completion specification.

Options:
[tab]-o option[tab]Set completion option OPTION for each NAME
[tab]-D[tab][tab]Change options for the "default" command completion
[tab]-E[tab][tab]Change options for the "empty" command completion
[tab]-I[tab][tab]Change options for completion on the initial word

Using `+o' instead of `-o' turns off the specified option.

Arguments:

Each NAME refers to a command for which a completion specification must
have previously been defined using the `complete' builtin. If no NAMEs
are supplied, compopt must be called by a function currently generating
completions, and the options for that currently-executing completion
generator are modified.

Exit Status:
Returns success unless an invalid option is supplied or NAME does not
have a completion specification defined.

585.

Read lines from the standard input into an indexed array variable.

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:
-d delim[tab]Use DELIM to terminate lines, instead of newline
-n count[tab]Copy at most COUNT lines. If COUNT is 0, all lines are copied
-O origin[tab]Begin assigning to ARRAY at index ORIGIN. The default index is 0
-s count[tab]Discard the first COUNT lines read
-t[tab]Remove a trailing DELIM from each line read (default newline)
-u fd[tab]Read lines from file descriptor FD instead of the standard input
-C callback[tab]Evaluate CALLBACK each time QUANTUM lines are read
-c quantum[tab]Specify the number of lines read between each call to
[tab][tab][tab]CALLBACK

Arguments:
ARRAY[tab]Array variable name to use for file data

If -C is supplied 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.

If not supplied with an explicit origin, mapfile will clear ARRAY before
assigning to it.

Exit Status:
Returns success unless an invalid option is given or ARRAY is readonly or
not an indexed array.