[root@www ~]# man exit
BASH_BUILTINS(1) BASH_BUILTINS(1)
NAME
bash, :, ., [, alias, bg, bind, break, builtin, cd, command, compgen, com-
plete, continue, declare, dirs, disown, echo, enable, eval, exec, exit,
export, fc, fg, getopts, hash, help, history, jobs, kill, let, local,
logout, popd, printf, pushd, pwd, read, readonly, return, set, shift,
shopt, source, suspend, test, times, trap, type, typeset, ulimit, umask,
unalias, unset, wait - bash built-in commands, see bash(1)
BASH BUILTIN COMMANDS
Unless otherwise noted, each builtin command documented in this section as
accepting options preceded by - accepts -- to signify the end of the
options. For example, the :, true, false, and test builtins do not accept
options.
: [arguments]
No effect; the command does nothing beyond expanding arguments and
performing any specified redirections. A zero exit code is
returned.
. filename [arguments]
source filename [arguments]
Read and execute commands from filename in the current shell envi-
ronment and return the exit status of the last command executed
from filename. If filename does not contain a slash, file names in
PATH are used to find the directory containing filename. The file
searched for in PATH need not be executable. When bash is not in
posix mode, the current directory is searched if no file is found
in PATH. If the sourcepath option to the shopt builtin command is
turned off, the PATH is not searched. If any arguments are sup-
plied, they become the positional parameters when filename is exe-
cuted. Otherwise the positional parameters are unchanged. The
return status is the status of the last command exited within the
script (0 if no commands are executed), and false if filename is
not found or cannot be read.
alias [-p] [name[=value] ...]
Alias with no arguments or with the -p option prints the list of
aliases in the form alias name=value on standard output. When
arguments are supplied, an alias is defined for each name whose
value is given. A trailing space in value causes the next word to
be checked for alias substitution when the alias is expanded. For
each name in the argument list for which no value is supplied, the
name and value of the alias is printed. Alias returns true unless
a name is given for which no alias has been defined.
bg [jobspec ...]
Resume each suspended job jobspec in the background, as if it had
been started with &. If jobspec is not present, the shell's notion
of the current job is used. bg jobspec returns 0 unless run when
job control is disabled or, when run with job control enabled, any
specified jobspec was not found or was started without job control.
bind [-m keymap] [-lpsvPSV]
bind [-m keymap] [-q function] [-u function] [-r keyseq]
bind [-m keymap] -f filename
bind [-m keymap] -x keyseq:shell-command
bind [-m keymap] keyseq:function-name
bind readline-command
Display current readline key and function bindings, bind a key
sequence to a readline function or macro, or set a readline vari-
able. Each non-option argument is a command as it would appear in
.inputrc, but each binding or command must be passed as a separate
argument; e.g., '"\C-x\C-r": re-read-init-file'. Options, if sup-
plied, have the following meanings:
-m keymap
Use keymap as the keymap to be affected by the subsequent
bindings. Acceptable keymap names are emacs, emacs-stan-
dard, emacs-meta, emacs-ctlx, vi, vi-move, vi-command, and
vi-insert. vi is equivalent to vi-command; emacs is equiva-
lent to emacs-standard.
-l List the names of all readline functions.
-p Display readline function names and bindings in such a way
that they can be re-read.
-P List current readline function names and bindings.
-v Display readline variable names and values in such a way
that they can be re-read.
-V List current readline variable names and values.
-s Display readline key sequences bound to macros and the
strings they output in such a way that they can be re-read.
-S Display readline key sequences bound to macros and the
strings they output.
-f filename
Read key bindings from filename.
-q function
Query about which keys invoke the named function.
-u function
Unbind all keys bound to the named function.
-r keyseq
Remove any current binding for keyseq.
-x keyseq:shell-command
Cause shell-command to be executed whenever keyseq is
entered.
The return value is 0 unless an unrecognized option is given or an
error occurred.
break [n]
Exit from within a for, while, until, or select loop. If n is
specified, break n levels. n must be >= 1. If n is greater than
the number of enclosing loops, all enclosing loops are exited. The
return value is 0 unless the shell is not executing a loop when
break is executed.
builtin shell-builtin [arguments]
Execute the specified shell builtin, passing it arguments, and
return its exit status. This is useful when defining a function
whose name is the same as a shell builtin, retaining the function-
ality of the builtin within the function. The cd builtin is com-
monly redefined this way. The return status is false if
shell-builtin is not a shell builtin command.
cd [-L|-P] [dir]
Change the current directory to dir. The variable HOME is the
default dir. The variable CDPATH defines the search path for the
directory containing dir. Alternative directory names in CDPATH
are separated by a colon (:). A null directory name in CDPATH is
the same as the current directory, i.e., ''.''. If dir begins with
a slash (/), then CDPATH is not used. The -P option says to use the
physical directory structure instead of following symbolic links
(see also the -P option to the set builtin command); the -L option
forces symbolic links to be followed. An argument of - is equiva-
lent to $OLDPWD. If a non-empty directory name from CDPATH is
used, or if - is the first argument, and the directory change is
successful, the absolute pathname of the new working directory is
written to the standard output. The return value is true if the
directory was successfully changed; false otherwise.
caller [expr]
Returns the context of any active subroutine call (a shell function
or a script executed with the . or source builtins. Without expr,
caller displays the line number and source filename of the current
subroutine call. If a non-negative integer is supplied as expr,
caller displays the line number, subroutine name, and source file
corresponding to that position in the current execution call stack.
This extra information may be used, for example, to print a stack
trace. The current frame is frame 0. The return value is 0 unless
the shell is not executing a subroutine call or expr does not cor-
respond to a valid position in the call stack.
command [-pVv] command [arg ...]
Run command with args suppressing the normal shell function lookup.
Only builtin commands or commands found in the PATH are executed.
If the -p option is given, the search for command is performed
using a default value for PATH that is guaranteed to find all of
the standard utilities. If either the -V or -v option is supplied,
a description of command is printed. The -v option causes a single
word indicating the command or file name used to invoke command to
be displayed; the -V option produces a more verbose description.
If the -V or -v option is supplied, the exit status is 0 if command
was found, and 1 if not. If neither option is supplied and an
error occurred or command cannot be found, the exit status is 127.
Otherwise, the exit status of the command builtin is the exit sta-
tus of command.
compgen [option] [word]
Generate possible completion matches for word according to the
options, which may be any option accepted by the complete builtin
with the exception of -p and -r, and write the matches to the stan-
dard output. When using the -F or -C options, the various shell
variables set by the programmable completion facilities, while
available, will not have useful values.
The matches will be generated in the same way as if the pro-
grammable completion code had generated them directly from a com-
pletion specification with the same flags. If word is specified,
only those completions matching word will be displayed.
The return value is true unless an invalid option is supplied, or
no matches were generated.
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 ...]
Specify how arguments to each name should be completed. If the -p
option is supplied, or if no options are supplied, existing comple-
tion 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 speci-
fications.
The process of applying these completion specifications when word
completion is attempted is described above under Programmable Com-
pletion.
Other options, if specified, have the following meanings. The
arguments to the -G, -W, and -X options (and, if necessary, the -P
and -S options) should be quoted to protect them from expansion
before the complete builtin is invoked.
-o comp-option
The comp-option controls several aspects of the compspec's
behavior beyond the simple generation of completions.
comp-option may be one of:
bashdefault
Perform the rest of the default bash completions if
the compspec generates no matches.
default Use readline's default filename completion if the
compspec generates no matches.
dirnames
Perform directory name completion if the compspec
generates no matches.
filenames
Tell readline that the compspec generates file-
names, so it can perform any filename-specific pro-
cessing (like adding a slash to directory names or
suppressing trailing spaces). Intended to be used
with shell functions.
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 gen-
erated, 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:
alias Alias names. May also be specified as -a.
arrayvar
Array variable names.
binding Readline key binding names.
builtin Names of shell builtin commands. May also be spec-
ified as -b.
command Command names. May also be specified as -c.
directory
Directory names. May also be specified as -d.
disabled
Names of disabled shell builtins.
enabled Names of enabled shell builtins.
export Names of exported shell variables. May also be
specified as -e.
file File names. May also be specified as -f.
function
Names of shell functions.
group Group names. May also be specified as -g.
helptopic
Help topics as accepted by the help builtin.
hostname
Hostnames, as taken from the file specified by the
HOSTFILE shell variable.
job Job names, if job control is active. May also be
specified as -j.
keyword Shell reserved words. May also be specified as -k.
running Names of running jobs, if job control is active.
service Service names. May also be specified as -s.
setopt Valid arguments for the -o option to the set
builtin.
shopt Shell option names as accepted by the shopt
builtin.
signal Signal names.
stopped Names of stopped jobs, if job control is active.
user User names. May also be specified as -u.
variable
Names of all shell variables. May also be speci-
fied as -v.
-G globpat
The filename expansion pattern globpat is expanded to gen-
erate the possible completions.
-W wordlist
The wordlist is split using the characters in the IFS spe-
cial 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 out-
put is used as the possible completions.
-F function
The shell function function is executed in the current
shell environment. When it finishes, the possible comple-
tions 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 comple-
tion not matching filterpat is removed.
-P prefix
prefix is added at the beginning of each possible comple-
tion after all other options have been applied.
-S suffix
suffix is appended to each possible completion after all
other options have been applied.
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 comple-
tion specification.
continue [n]
Resume the next iteration of the enclosing for, while, until, or
select loop. If n is specified, resume at the nth enclosing loop.
n must be >= 1. If n is greater than the number of enclosing loops,
the last enclosing loop (the ''top-level'' loop) is resumed. The
return value is 0 unless the shell is not executing a loop when
continue is executed.
declare [-afFirtx] [-p] [name[=value] ...]
typeset [-afFirtx] [-p] [name[=value] ...]
Declare variables and/or give them attributes. If no names are
given then display the values of variables. 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, the
source file name and line number where the function is defined are
displayed as well. The -F option implies -f. The following
options can be used to restrict output to variables with the speci-
fied attribute or to give variables attributes:
-a Each name is an array variable (see Arrays above).
-f Use function names only.
-i The variable is treated as an integer; arithmetic evaluation
(see ARITHMETIC EVALUATION ) is performed when the variable
is assigned a value.
-r Make names readonly. These names cannot then be assigned
values by subsequent assignment statements or unset.
-t Give each name the trace attribute. Traced functions
inherit the DEBUG and RETURN traps from the calling shell.
The trace attribute has no special meaning for variables.
-x Mark names for export to subsequent commands via the envi-
ronment.
Using '+' instead of '-' turns off the attribute instead, with the
exception that +a may not be used to destroy an array variable.
When used in a function, makes each name local, as with the local
command. If a variable name is followed by =value, the value of
the variable is set to value. The return value is 0 unless an
invalid option is encountered, an attempt is made to define a func-
tion using ''-f foo=bar'', an attempt is made to assign a value to
a readonly variable, an attempt is made to assign a value to an
array variable without using the compound assignment syntax (see
Arrays above), one of the names is not a valid shell variable name,
an attempt is made to turn off readonly status for a readonly vari-
able, an attempt is made to turn off array status for an array
variable, or an attempt is made to display a non-existent function
with -f.
dirs [-clpv] [+n] [-n]
Without options, displays the list of currently remembered directo-
ries. The default display is on a single line with directory names
separated by spaces. Directories are added to the list with the
pushd command; the popd command removes entries from the list.
+n Displays the nth entry counting from the left of the list
shown by dirs when invoked without options, starting with
zero.
-n Displays the nth entry counting from the right of the list
shown by dirs when invoked without options, starting with
zero.
-c Clears the directory stack by deleting all of the entries.
-l Produces a longer listing; the default listing format uses a
tilde to denote the home directory.
-p Print the directory stack with one entry per line.
-v Print the directory stack with one entry per line, prefixing
each entry with its index in the stack.
The return value is 0 unless an invalid option is supplied or n
indexes beyond the end of the directory stack.
disown [-ar] [-h] [jobspec ...]
Without options, each jobspec is removed from the table of active
jobs. If the -h option is given, each jobspec is not removed from
the table, but is marked so that SIGHUP is not sent to the job if
the shell receives a SIGHUP. If no jobspec is present, and neither
the -a nor the -r option is supplied, the current job is used. If
no jobspec is supplied, the -a option means to remove or mark all
jobs; the -r option without a jobspec argument restricts operation
to running jobs. The return value is 0 unless a jobspec does not
specify a valid job.
echo [-neE] [arg ...]
Output the args, separated by spaces, followed by a newline. The
return status is always 0. If -n is specified, the trailing new-
line is suppressed. If the -e option is given, interpretation of
the following backslash-escaped characters is enabled. The -E
option disables the interpretation of these 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 does not
interpret -- to mean the end of options. echo interprets the fol-
lowing escape sequences:
\a alert (bell)
\b backspace
\c suppress trailing newline
\e an escape character
\f form feed
\n new line
\r carriage return
\t horizontal tab
\v vertical tab
\\ backslash
\0nnn the eight-bit character whose value is the octal value nnn
(zero to three octal digits)
\nnn the eight-bit character whose value is the octal value nnn
(one to three octal digits)
\xHH the eight-bit character whose value is the hexadecimal value
HH (one or two hex digits)
enable [-adnps] [-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
shell normally searches for builtins before disk commands. If -n
is used, each name is disabled; otherwise, names are enabled. For
example, to use the test binary found via the PATH instead of the
shell builtin version, run ''enable -n test''. The -f option means
to load the new builtin command name from shared object filename,
on systems that support dynamic loading. The -d option will delete
a builtin previously loaded with -f. If no name arguments are
given, or if the -p option is supplied, a list of shell builtins is
printed. With no other option arguments, the list consists of all
enabled shell builtins. If -n is supplied, only disabled builtins
are printed. If -a is supplied, the list printed includes all
builtins, with an indication of whether or not each is enabled. If
-s is supplied, the output is restricted to the POSIX special
builtins. The return value is 0 unless a name is not a shell
builtin or there is an error loading a new builtin from a shared
object.
eval [arg ...]
The args are read and concatenated together into a single command.
This command is then read and executed by the shell, and its exit
status is returned as the value of eval. If there are no args, or
only null arguments, eval returns 0.
exec [-cl] [-a name] [command [arguments]]
If command is specified, it replaces the shell. No new process is
created. The arguments become the arguments to command. If the -l
option is supplied, the shell places a dash at the beginning of the
zeroth arg passed to command. This is what login(1) 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 the
executed command. If command cannot be executed for some reason, a
non-interactive shell exits, unless the shell option execfail is
enabled, in which case it returns failure. An interactive shell
returns failure if the file cannot be executed. If command is not
specified, any redirections take effect in the current shell, and
the return status is 0. If there is a redirection error, the
return status is 1.
exit [n]
Cause the shell to exit with a status of n. If n is omitted, the
exit status is that of the last command executed. A trap on EXIT
is executed before the shell terminates.
export [-fn] [name[=word]] ...
export -p
The supplied names are marked for automatic export to the environ-
ment of subsequently executed commands. If the -f option is given,
the names refer to functions. If no names are given, or if the -p
option is supplied, a list of all names that are exported in this
shell is printed. The -n option causes the export property to be
removed from each name. If a variable name is followed by =word,
the value of the variable is set to word. export returns an exit
status of 0 unless an invalid option is encountered, one of the
names is not a valid shell variable name, or -f is supplied with a
name that is not a function.
fc [-e ename] [-nlr] [first] [last]
fc -s [pat=rep] [cmd]
Fix Command. In the first form, a range of commands from first to
last is selected from the history list. First and last may be
specified as a string (to locate the last command beginning with
that string) or as a number (an index into the history list, where
a negative number is used as an offset from the current command
number). If last is not specified it is set to the current command
for listing (so that ''fc -l -10'' prints the last 10 commands) and
to first otherwise. If first is not specified it is set to the
previous command for editing and -16 for listing.
The -n option suppresses the command numbers when listing. The -r
option reverses the order of the commands. If the -l option is
given, the commands are listed on standard output. Otherwise, the
editor given by ename is invoked on a file containing those com-
mands. If ename is not given, the value of the FCEDIT variable is
used, and the value of EDITOR if FCEDIT is not set. If neither
variable is set, is used. When editing is complete, the edited
commands are echoed and executed.
In the second form, command is re-executed after each instance of
pat is replaced by rep. A useful alias to use with this is ''r="fc
-s"'', so that typing ''r cc'' runs the last command beginning with
''cc'' and typing ''r'' re-executes the last command.
If the first form is used, the return value is 0 unless an invalid
option is encountered or first or last specify history lines out of
range. If the -e option is supplied, the return value is the value
of the last command executed or failure if an error occurs with the
temporary file of commands. If the second form is used, the return
status is that of the command re-executed, unless cmd does not
specify a valid history line, in which case fc returns failure.
fg [jobspec]
Resume jobspec in the foreground, and make it the current job. If
jobspec is not present, the shell's notion of the current job is
used. The return value is that of the command placed into the
foreground, or failure if run when job control is disabled or, when
run with job control enabled, if jobspec does not specify a valid
job or jobspec specifies a job that was started without job con-
trol.
getopts optstring name [args]
getopts is used by shell procedures to parse positional parameters.
optstring contains the option characters to be recognized; if a
character is followed by a colon, the option is expected to have an
argument, which should be separated from it by white space. The
colon and question mark characters may not be used as option char-
acters. Each time it is invoked, getopts places the next option in
the shell variable name, initializing name if it does not exist,
and the index of the next argument to be processed into the vari-
able OPTIND. OPTIND is initialized to 1 each time the shell or a
shell script is invoked. When an option requires an argument,
getopts places that argument into the variable OPTARG. The shell
does not reset OPTIND automatically; it must be manually reset
between multiple calls to getopts within the same shell invocation
if a new set of parameters is to be used.
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 ?.
getopts normally parses the positional parameters, but if more
arguments are given in args, getopts parses those instead.
getopts can report errors in two ways. If the first character of
optstring is a colon, silent error reporting is used. In normal
operation diagnostic messages are printed when invalid options or
missing option arguments are encountered. If the variable OPTERR
is set to 0, no error messages will be displayed, even if the first
character of optstring is not a colon.
If an invalid option is seen, getopts places ? into name and, if
not silent, prints an error message and unsets OPTARG. If getopts
is silent, the option character found is placed in OPTARG and no
diagnostic message is printed.
If a required argument is not found, and getopts is not silent, a
question mark (?) is placed in name, OPTARG is unset, and a diag-
nostic message is printed. If getopts is silent, then a colon (:)
is placed in name and OPTARG is set to the option character found.
getopts returns true if an option, specified or unspecified, is
found. It returns false if the end of options is encountered or an
error occurs.
hash [-lr] [-p filename] [-dt] [name]
For each name, the full file name of the command is determined by
searching the directories in $PATH and remembered. If the -p
option is supplied, no path search is performed, and filename is
used as the full file name of the command. 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 corre-
sponds 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 sta-
tus is true unless a name is not found or an invalid option is sup-
plied.
help [-s] [pattern]
Display helpful information about builtin commands. If pattern is
specified, help gives detailed help on all commands matching pat-
tern; otherwise help for all the builtins and shell control struc-
tures is printed. The -s option restricts the information dis-
played to a short usage synopsis. The return status is 0 unless no
command matches pattern.
history [n]
history -c
history -d offset
history -anrw [filename]
history -p arg [arg ...]
history -s arg [arg ...]
With no options, display the command history list with line num-
bers. Lines listed with a * have been modified. An argument of n
lists only the last n lines. If the shell variable HISTTIMEFORMAT
is set and not null, it is used as a format string for strftime(3)
to display the time stamp associated with each displayed history
entry. No intervening blank is printed between the formatted time
stamp and the history line. If filename is supplied, it is used as
the name of the history file; if not, the value of HISTFILE is
used. Options, if supplied, have the following meanings:
-c Clear the history list by deleting all the entries.
-d offset
Delete the history entry at position offset.
-a Append the ''new'' history lines (history lines entered
since the beginning of the current bash session) to the his-
tory file.
-n Read the history lines not already read from the history
file into the current history list. These are lines
appended to the history file since the beginning of the cur-
rent bash session.
-r Read the contents of the history file and use them as the
current history.
-w Write the current history to the history file, overwriting
the history file's contents.
-p Perform history substitution on the following args and dis-
play the result on the standard output. Does not store the
results in the history list. Each arg must be quoted to
disable normal history expansion.
-s Store the args in the history list as a single entry. The
last command in the history list is removed before the args
are added.
If the HISTTIMEFORMAT is set, the time stamp information associated
with each history entry is written to the history file. The return
value is 0 unless an invalid option is encountered, an error occurs
while reading or writing the history file, an invalid offset is
supplied as an argument to -d, or the history expansion supplied as
an argument to -p fails.
jobs [-lnprs] [ jobspec ... ]
jobs -x command [ args ... ]
The first form lists the active jobs. The options have the follow-
ing meanings:
-l List process IDs in addition to the normal information.
-p List only the process ID of the job's process group leader.
-n Display information only about jobs that have changed status
since the user was last notified of their status.
-r Restrict output to running jobs.
-s Restrict output to stopped jobs.
If jobspec is given, output is restricted to information about that
job. The return status is 0 unless an invalid option is encoun-
tered or an invalid jobspec is supplied.
If the -x option is supplied, jobs replaces any jobspec found in
command or args with the corresponding process group ID, and exe-
cutes command passing it args, returning its exit status.
kill [-s sigspec | -n signum | -sigspec] [pid | jobspec] ...
kill -l [sigspec | exit_status]
Send the signal named by sigspec or signum to the processes named
by pid or jobspec. sigspec is either a case-insensitive signal
name such as SIGKILL (with or without the SIG prefix) or a signal
number; signum is a signal number. If sigspec is not present, then
SIGTERM is assumed. An argument of -l lists the signal names. If
any arguments are supplied when -l is given, the names of the sig-
nals corresponding to the arguments are listed, and the return sta-
tus is 0. The exit_status argument to -l is a number specifying
either a signal number or the exit status of a process terminated
by a signal. kill returns true if at least one signal was success-
fully sent, or false if an error occurs or an invalid option is
encountered.
let arg [arg ...]
Each arg is an arithmetic expression to be evaluated (see ARITH-
METIC EVALUATION). If the last arg evaluates to 0, let returns 1;
0 is returned otherwise.
local [option] [name[=value] ...]
For each argument, a local variable named name is created, and
assigned value. The option can be any of the options accepted by
declare. When local is used within a function, it causes the vari-
able name to have a visible scope restricted to that function and
its children. With no operands, local writes a list of local vari-
ables to the standard output. It is an error to use local when not
within a function. The return status is 0 unless local is used
outside a function, an invalid name is supplied, or name is a read-
only variable.
logout Exit a login shell.
popd [-n] [+n] [-n]
Removes entries from the directory stack. With no arguments,
removes the top directory from the stack, and performs a cd to the
new top directory. Arguments, if supplied, have the following
meanings:
+n Removes the nth entry counting from the left of the list
shown by dirs, starting with zero. For example: ''popd +0''
removes the first directory, ''popd +1'' the second.
-n Removes the nth entry counting from the right of the list
shown by dirs, starting with zero. For example: ''popd -0''
removes the last directory, ''popd -1'' the next to last.
-n Suppresses the normal change of directory when removing
directories from the stack, so that only the stack is manip-
ulated.
If the popd command is successful, a dirs is performed as well, and
the return status is 0. popd returns false if an invalid option is
encountered, the directory stack is empty, a non-existent directory
stack entry is specified, or the directory change fails.
printf [-v var] format [arguments]
Write the formatted arguments to the standard output under the con-
trol of the format. The format is a character string which con-
tains 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 specifica-
tions, each of which causes printing of the next successive argu-
ment. 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 cor-
responding argument in a format that can be reused as shell input.
The -v option causes the output to be assigned to the variable var
rather than being printed to the standard output.
The format is reused as necessary to consume all of the arguments.
If the format requires more arguments than are supplied, the extra
format specifications behave as if a zero value or null string, as
appropriate, had been supplied. The return value is zero on suc-
cess, non-zero on failure.
pushd [-n] [dir]
pushd [-n] [+n] [-n]
Adds a directory to the top of the directory stack, or rotates the
stack, making the new top of the stack the current working direc-
tory. With no arguments, exchanges the top two directories and
returns 0, unless the directory stack is empty. Arguments, if sup-
plied, have the following meanings:
+n Rotates the stack so that the nth directory (counting from
the left of the list shown by dirs, starting with zero) is
at the top.
-n Rotates the stack so that the nth directory (counting from
the right of the list shown by dirs, starting with zero) is
at the top.
-n Suppresses the normal change of directory when adding direc-
tories to the stack, so that only the stack is manipulated.
dir Adds dir to the directory stack at the top, making it the
new current working directory.
If the pushd command is successful, a dirs is performed as well.
If the first form is used, pushd returns 0 unless the cd to dir
fails. With the second form, pushd returns 0 unless the directory
stack is empty, a non-existent directory stack element is speci-
fied, or the directory change to the specified new current direc-
tory fails.
pwd [-LP]
Print the absolute pathname of the current working directory. The
pathname printed contains no symbolic links if the -P option is
supplied or the -o physical option to the set builtin command is
enabled. If the -L option is used, the pathname printed may con-
tain symbolic links. The return status is 0 unless an error occurs
while reading the name of the current directory or an invalid
option is supplied.
read [-ers] [-u fd] [-t timeout] [-a aname] [-p prompt] [-n nchars] [-d
delim] [name ...]
One line is read from the standard input, or from the file descrip-
tor fd supplied as an argument to the -u option, and the first word
is assigned to the first name, the second word to the second name,
and so on, with leftover words and their intervening separators
assigned to the last name. If there are fewer words read from the
input stream than names, the remaining names are assigned empty
values. The characters in IFS are used to split the line into
words. The backslash character (\) may be used to remove any spe-
cial meaning for the next character read and for line continuation.
Options, if supplied, have the following meanings:
-a aname
The words are assigned to sequential indices of the array
variable aname, starting at 0. aname is unset before any
new values are assigned. Other name arguments are ignored.
-d delim
The first character of delim is used to terminate the input
line, rather than newline.
-e If the standard input is coming from a terminal, readline
(see READLINE above) is used to obtain the line.
-n nchars
read returns after reading nchars characters rather than
waiting for a complete line of input.
-p prompt
Display prompt on standard error, without a trailing new-
line, before attempting to read any input. The prompt is
displayed only if input is coming from a terminal.
-r Backslash does not act as an escape character. The back-
slash is considered to be part of the line. In particular,
a backslash-newline pair may not be used as a line continua-
tion.
-s Silent mode. If input is coming from a terminal, characters
are not echoed.
-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.
-u fd Read input from file descriptor fd.
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.
readonly [-apf] [name[=word] ...]
The given names are marked readonly; the values of these names may
not be changed by subsequent assignment. If the -f option is sup-
plied, the functions corresponding to the names are so marked. The
-a option restricts the variables to arrays. 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 =word, the value of the variable is set to word. The return
status is 0 unless an invalid option is encountered, one of the
names is not a valid shell variable name, or -f is supplied with a
name that is not a function.
return [n]
Causes a function to exit with the return value specified by n. If
n is omitted, the return status is that of the last command exe-
cuted in the function body. If used outside a function, but during
execution of a script by the . (source) command, it causes the
shell to stop executing that script and return either n or the exit
status of the last command executed within the script as the exit
status of the script. If used outside a function and not during
execution of a script by ., the return status is false. Any com-
mand associated with the RETURN trap is executed before execution
resumes after the function or script.
set [--abefhkmnptuvxBCHP] [-o option] [arg ...]
Without options, the name and value of each shell variable are dis-
played in a format that can 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. The
output is sorted according to the current locale. When options are
specified, they set or unset shell attributes. Any arguments
remaining after the options are processed are treated as values for
the positional parameters and are assigned, in order, to $1, $2,
... $n. Options, if specified, have the following meanings:
-a Automatically mark variables and functions which are modi-
fied or created for export to the environment of subsequent
commands.
-b Report the status of terminated background jobs immedi-
ately, rather than before the next primary prompt. This is
effective only when job control is enabled.
-e Exit immediately if a simple command (see SHELL GRAMMAR
above) exits with 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 a && or || list, or if the
command's return value is being inverted via !. A trap on
ERR, if set, is executed before the shell exits.
-f Disable pathname expansion.
-h Remember the location of commands as they are looked up for
execution. This is enabled by default.
-k All arguments in the form of assignment statements are
placed in the environment for a command, not just those
that precede the command name.
-m Monitor mode. Job control is enabled. This option is on
by default for interactive shells on systems that support
it (see JOB CONTROL above). Background processes run in a
separate process group and a line containing their exit
status is printed upon their completion.
-n Read commands but do not execute them. This may be used to
check a shell script for syntax errors. This is ignored by
interactive shells.
-o option-name
The option-name can be one of the following:
allexport
Same as -a.
braceexpand
Same as -B.
emacs Use an emacs-style command line editing interface.
This is enabled by default when the shell is inter-
active, unless the shell is started with the
--noediting option.
errtrace
Same as -E.
functrace
Same as -T.
errexit Same as -e.
hashall Same as -h.
histexpand
Same as -H.
history Enable command history, as described above under
HISTORY. This option is on by default in interac-
tive shells.
ignoreeof
The effect is as if the shell command
''IGNOREEOF=10'' had been executed (see Shell Vari-
ables above).
keyword Same as -k.
monitor Same as -m.
noclobber
Same as -C.
noexec Same as -n.
noglob Same as -f. nolog Currently ignored.
notify Same as -b.
nounset Same as -u.
onecmd Same as -t.
physical
Same as -P.
pipefail
If set, the return value of a pipeline is the value
of the last (rightmost) command to exit with a non-
zero status, or zero if all commands in the
pipeline exit successfully. This option is dis-
abled by default.
posix Change the behavior of bash where the default oper-
ation differs from the POSIX 1003.2 standard to
match the standard (posix mode).
privileged
Same as -p.
verbose Same as -v.
vi Use a vi-style command line editing interface.
xtrace Same as -x.
If -o is supplied with no option-name, the values of the
current options are printed. If +o is supplied with no
option-name, a series of set commands to recreate the cur-
rent option settings is displayed on the standard output.
-p Turn on privileged mode. In this mode, the $ENV and
$BASH_ENV files are not processed, shell functions are not
inherited from the environment, and the SHELLOPTS variable,
if it appears in the environment, is ignored. If the shell
is started with the effective user (group) id not equal to
the real user (group) id, and the -p option is not sup-
plied, these actions are taken and the effective user id is
set to the real user id. If the -p option is supplied at
startup, the effective user id is not reset. Turning this
option off causes the effective user and group ids to be
set to the real user and group ids.
-t Exit after reading and executing one command.
-u Treat unset variables as an error when performing parameter
expansion. If expansion is attempted on an unset variable,
the shell prints an error message, and, if not interactive,
exits with a non-zero status.
-v Print shell input lines as they are read.
-x After expanding each simple command, for command, case com-
mand, select command, or arithmetic for command, display
the expanded value of PS4, followed by the command and its
expanded arguments or associated word list.
-B The shell performs brace expansion (see Brace Expansion
above). This is on by default.
-C If set, bash does not overwrite an existing file with the
>, >&, and <> redirection operators. This may be overrid-
den when creating output files by using the redirection
operator >| instead of >.
-E If set, any trap on ERR is inherited by shell functions,
command substitutions, and commands executed in a subshell
environment. The ERR trap is normally not inherited in
such cases.
-H Enable ! style history substitution. This option is on by
default when the shell is interactive.
-P If set, the shell does not follow symbolic links when exe-
cuting commands such as cd that change the current working
directory. It uses the physical directory structure
instead. By default, bash follows the logical chain of
directories when performing commands which change the cur-
rent directory.
-T If set, any traps on DEBUG and RETURN are inherited by
shell functions, command substitutions, and commands exe-
cuted 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 args, even if some of them begin with a -.
- Signal the end of options, cause all remaining args to be
assigned to the positional parameters. The -x and -v
options are turned off. If there are no args, the posi-
tional parameters remain unchanged.
The options are off by default unless otherwise noted. Using +
rather than - causes these options to be turned off. The options
can also be specified as arguments to an invocation of the shell.
The current set of options may be found in $-. The return status
is always true unless an invalid option is encountered.
shift [n]
The positional parameters from n+1 ... are renamed to $1 ....
Parameters represented by the numbers $# down to $#-n+1 are unset.
n must be a non-negative number less than or equal to $#. If n is
0, no parameters are changed. If n is not given, it is assumed to
be 1. If n is greater than $#, the positional parameters are not
changed. The return status is greater than zero if n is greater
than $# or less than zero; otherwise 0.
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 (quiet mode); 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.
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 (unset) by
default.
The return status when listing options is zero if all optnames are
enabled, non-zero otherwise. When setting or unsetting options,
the return status is zero unless an optname is not a valid shell
option.
The list of shopt options is:
cdable_vars
If 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 compo-
nent in a cd command will be corrected. The errors checked
for are transposed characters, a missing character, and one
character too many. If a correction is found, the cor-
rected file name is printed, and the command proceeds.
This option is only used by interactive shells.
checkhash
If set, bash checks that a command found in the hash table
exists before trying to execute it. If a hashed command no
longer exists, a normal path search is performed.
checkwinsize
If set, bash checks the window size after each command and,
if necessary, updates the values of LINES and COLUMNS.
cmdhist If set, bash attempts to save all lines of a multiple-line
command in the same history entry. This allows easy re-
editing of multi-line commands.
dotglob If set, bash includes filenames beginning with a '.' in the
results of pathname expansion.
execfail
If 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 above under
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 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 exe-
cuted.
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 above.
5. Function tracing is enabled: command substitution,
shell functions, and subshells invoked with ( com-
mand ) inherit the DEBUG and RETURN traps.
6. Error tracing is enabled: command substitution,
shell functions, and subshells invoked with ( com-
mand ) inherit the ERROR trap.
extglob If set, the extended pattern matching features described
above under Pathname Expansion 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 path-
name expansion result in an expansion error.
force_fignore
If set, the suffixes specified by the FIGNORE shell vari-
able cause words to be ignored when performing word comple-
tion even if the ignored words are the only possible com-
pletions. See SHELL VARIABLES above 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 (see Completing under READLINE above).
This is enabled by default.
huponexit
If set, bash will send SIGHUP to all jobs when an interac-
tive login shell exits.
interactive_comments
If set, allow a word beginning with # to cause that word
and all remaining characters on that line to be ignored in
an interactive shell (see COMMENTS above). This option is
enabled by default.
lithist If set, and the cmdhist option is enabled, multi-line com-
mands 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 (see INVOCATION above). 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 fash-
ion when performing pathname expansion (see Pathname Expan-
sion above).
nocasematch
If set, bash matches patterns in a case-insensitive fashion
when performing matching while executing case or [[ condi-
tional commands.
nullglob
If set, bash allows patterns which match no files (see
Pathname Expansion above) to expand to a null string,
rather than themselves.
progcomp
If set, the programmable completion facilities (see Pro-
grammable Completion above) 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 in PROMPTING above. This
option is enabled by default.
restricted_shell
The shell sets this option if it is started in restricted
mode (see RESTRICTED SHELL below). The value may not be
changed. This is not reset when the startup files are exe-
cuted, allowing the startup files to discover whether or
not a shell is restricted.
shift_verbose
If 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 argu-
ment. This option is enabled by default.
xpg_echo
If set, the echo builtin expands backslash-escape sequences
by default.
suspend [-f]
Suspend the execution of this shell until it receives a SIGCONT
signal. The -f option says not to complain if this is a login
shell; just suspend anyway. The return status is 0 unless the
shell is a login shell and -f is not supplied, or if job control is
not enabled.
test expr
[ expr ]
Return a status of 0 or 1 depending on the evaluation of the condi-
tional expression expr. Each operator and operand must be a sepa-
rate argument. Expressions are composed of the primaries described
above under CONDITIONAL EXPRESSIONS. test does not accept any
options, nor does it accept and ignore an argument of -- as signi-
fying the end of options.
Expressions may be combined using the following operators, listed
in decreasing order of precedence.
! expr True if expr is false.
( expr )
Returns the value of expr. This may be used to override the
normal precedence of operators.
expr1 -a expr2
True if both expr1 and expr2 are true.
expr1 -o expr2
True if either expr1 or expr2 is true.
test and [ evaluate conditional expressions using a set of rules
based on the number of arguments.
0 arguments
The expression is false.
1 argument
The expression is true if and only if the argument is not
null.
2 arguments
If the first argument is !, the expression is true if and
only if the second argument is null. If the first argument
is one of the unary conditional operators listed above under
CONDITIONAL EXPRESSIONS, the expression is true if the unary
test is true. If the first argument is not a valid unary
conditional operator, the expression is false.
3 arguments
If the second argument is one of the binary conditional
operators listed above under 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.
4 arguments
If the first argument is !, the result is the negation of
the three-argument expression composed of the remaining
arguments. Otherwise, the expression is parsed and evalu-
ated according to precedence using the rules listed above.
5 or more arguments
The expression is parsed and evaluated according to prece-
dence using the rules listed above.
times Print the accumulated user and system times for the shell and for
processes run from the shell. The return status is 0.
trap [-lp] [[arg] sigspec ...]
The command arg is to be read and executed when the shell receives
signal(s) sigspec. If arg is absent (and there is a single
sigspec) or -, each specified signal is reset to its original dis-
position (the value it had upon entrance to the shell). If arg is
the null string the signal specified by each sigspec is ignored by
the shell and by the commands it invokes. If arg is not present
and -p has been supplied, then the trap commands associated with
each sigspec are displayed. If no arguments are supplied or if
only -p is given, trap prints the list of commands associated with
each signal. The -l option causes the shell to print a list of
signal names and their corresponding numbers. Each sigspec is
either a signal name defined in <signal.h>, or a signal number.
Signal names are case insensitive and the SIG prefix is optional.
If a sigspec is EXIT (0) the command arg is executed on exit from
the shell. If a sigspec is DEBUG, the command arg is executed
before every simple command, for command, case command, select com-
mand, every arithmetic for command, and before the first command
executes in a shell function (see SHELL GRAMMAR above). Refer to
the description of the extdebug option to the shopt builtin for
details of its effect on the DEBUG trap. If a sigspec is ERR, the
command arg is executed whenever a simple command has a non-zero
exit status, subject to the following conditions. The ERR trap is
not executed if the failed command is part of the command list
immediately following a while or until keyword, part of the test in
an if statement, part of a && or || list, or if the command's
return value is being inverted via !. These are the same condi-
tions obeyed by the errexit option. If a sigspec is RETURN, the
command arg is executed each time a shell function or a script exe-
cuted with the . or source builtins finishes executing. Signals
ignored upon entry to the shell cannot be trapped or reset.
Trapped signals are reset to their original values in a child pro-
cess when it is created. The return status is false if any sigspec
is invalid; otherwise trap returns true.
type [-aftpP] name [name ...]
With no options, indicate how each name would be interpreted if
used as a command name. If the -t option is used, type prints a
string which is one of alias, keyword, function, builtin, or file
if name is an alias, shell reserved word, function, builtin, or
disk file, respectively. If the name is not found, then nothing is
printed, and an exit status of false is returned. If the -p option
is used, type either returns the name of the disk file that would
be executed if name were specified as a command name, or nothing if
''type -t name'' would not return file. The -P option forces a
PATH search for each name, even if ''type -t name'' 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 prints all of the places that contain an
executable named name. This includes aliases and functions, if and
only if the -p option is not also used. The table of hashed com-
mands is not consulted when using -a. The -f option suppresses
shell function lookup, as with the command builtin. type returns
true if any of the arguments are found, false if none are found.
ulimit [-SHacdefilmnpqrstuvx [limit]]
Provides control over the resources available to the shell and to
processes started by it, on systems that allow such control. The
-H and -S options specify that the hard or soft limit is set for
the given resource. A hard limit cannot be increased once it is
set; a soft limit may be increased up to the value of the hard
limit. If neither -H nor -S is specified, both the soft and hard
limits are set. The value of limit can be a number in the unit
specified for the resource or one of the special values hard, soft,
or unlimited, which stand for the current hard limit, the current
soft limit, and no limit, respectively. If limit is omitted, the
current value of the soft limit of the resource is printed, unless
the -H option is given. When more than one resource is specified,
the limit name and unit are printed before the value. Other
options are interpreted as follows:
-a All current limits are reported
-c The maximum size of core files created
-d The maximum size of a process's data segment
-e The maximum scheduling priority ('nice')
-f The maximum size of files created by the shell
-i The maximum number of pending signals
-l The maximum size that may be locked into memory
-m The maximum resident set size
-n The maximum number of open file descriptors (most systems do
not allow this value to be set)
-p The pipe size in 512-byte blocks (this may not be set)
-q The maximum number of bytes in POSIX message queues
-r The maximum rt priority
-s The maximum stack size
-t The maximum amount of cpu time in seconds
-u The maximum number of processes available to a single user
-v The maximum amount of virtual memory available to the shell
-x The maximum number of file locks
If limit is given, it is the new value of the specified resource
(the -a option is display only). If no option is given, then -f is
assumed. Values are in 1024-byte increments, except for -t, which
is in seconds, -p, which is in units of 512-byte blocks, and -n and
-u, which are unscaled values. The return status is 0 unless an
invalid option or argument is supplied, or an error occurs while
setting a new limit.
umask [-p] [-S] [mode]
The user file-creation mask is set to mode. If mode begins with a
digit, it is interpreted as an octal number; otherwise it is inter-
preted as a symbolic mode mask similar to that accepted by
chmod(1). If mode is omitted, the current value of the mask is
printed. The -S option causes the mask to be printed in symbolic
form; the default output is an octal number. If the -p option is
supplied, and mode is omitted, the output is in a form that may be
reused as input. The return status is 0 if the mode was success-
fully changed or if no mode argument was supplied, and false other-
wise.
unalias [-a] [name ...]
Remove each name from the list of defined aliases. If -a is sup-
plied, all alias definitions are removed. The return value is true
unless a supplied name is not a defined alias.
unset [-fv] [name ...]
For each name, remove the corresponding variable or function. If
no options are supplied, or the -v option is given, each name
refers to a shell variable. Read-only variables may not be unset.
If -f is specified, each name refers to a shell function, and the
function definition is removed. Each unset variable or function is
removed from the environment passed to subsequent commands. If any
of RANDOM, SECONDS, LINENO, HISTCMD, FUNCNAME, GROUPS, or DIRSTACK
are unset, they lose their special properties, even if they are
subsequently reset. The exit status is true unless a name is read-
only.
wait [n ...]
Wait for each specified process and return its termination status.
Each n may be a process ID or a job specification; if a job spec is
given, all processes in that job's pipeline are waited for. If n
is not given, all currently active child processes are waited for,
and the return status is zero. If n specifies a non-existent pro-
cess or job, the return status is 127. Otherwise, the return sta-
tus is the exit status of the last process or job waited for.
SEE ALSO
bash(1), sh(1)
GNU Bash-3.0 2004 Apr 20 BASH_BUILTINS(1) |
