alias

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. Otherwise, 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. Alias returns true unless a NAME is given for which no alias has been defined.

bg

bg [JOB_SPEC ...]

Place each JOB_SPEC in the background, as if it had been started with &. If JOB_SPEC is not present, the shell's notion of the current job is used.

bind

bind [-lpvsPVS] [-m keymap] [-f filename]
   [-q name] [-u name] [-r keyseq]
   [-x keyseq:shell-command] 
   [keyseq:readline-function or readline-command]

Bind a key sequence to a Readline function or a macro, or set a Readline variable. The non-option argument syntax is equivalent to that found in ~/.inputrc, but must be passed as a single argument: bind "\C-x\C-r": re-read-init-file.

break

break [N]

Exit from within a for, while or until loop. If N is specified, break N levels.

builtin

builtin [shell-builtin [arg ...]]

Run a shell builtin. This is useful when you wish to rename a shell builtin to be a function, but need the functionality of the builtin within the function itself.

caller

caller [EXPR]

Returns the context of the current subroutine call. Without EXPR, returns $line $filename. With EXPR, returns $line $subroutine $filename; this extra information can be used to provide a stack trace.

case

case WORD in [PATTERN [| PATTERN] [COMMANDS;;] ... esac

Selectively execute COMMANDS based upon WORD matching PATTERN. The `|' is used to separate multiple patterns.

cd

cd [-L|-P] [dir]

Change the current directory to DIR.

command

command [-pVv]
command [arg ...]

Runs COMMAND with ARGS ignoring shell functions. If you have a shell function called `ls', and you wish to call the command `ls', you can say "command ls". If the -p option is given, a default value is used for PATH that is guaranteed to find all of the standard utilities. If the -V or -v option is given, a string is printed describing COMMAND. The -V option produces a more verbose description.

compgen

compgen [-abcdefgjksuv] [-o option] [-A action]
  [-G globpat] [-W wordlist] [-P prefix]
  [-S suffix] [-X filterpat] [-F function]
  [-C command] [WORD]

Display the 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.

complete

complete [-abcdefgjksuv] [-pr] [-o option]
   [-A action] [-G globpat] [-W wordlist] [-P prefix]
   [-S suffix] [-X filterpat] [-F function] [-C command]
   [name ...]

For each NAME, specify how arguments are to 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.

continue

continue [N]

Resume the next iteration of the enclosing FOR, WHILE or UNTIL loop. If N is specified, resume at the N-th enclosing loop.

declare

declare [-afFirtx] [-p] [name[=value] ...]

Declare variables and/or 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.

dirs

dirs [-clpv] [+N] [-N]

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.

disown

disown [-h] [-ar] [JOBSPEC ...]

By default, removes each JOBSPEC argument from the table of active jobs. If the -h option is given, the job is not removed from the table, but is marked so that SIGHUP is not sent to the job if the shell receives a SIGHUP. The -a option, when JOBSPEC is not supplied, means to remove all jobs from the job table; the -r option means to remove only running jobs.

echo

echo [-neE] [arg ...]

Output the ARGs. If -n is specified, the trailing newline is suppressed. If the -e option is given, interpretation of the following backslash-escaped characters is turned on:

You can explicitly turn off the interpretation of the above characters with the -E option.

enable

enable [-pnds] [-a] [-f filename] [name...]

Enable and disable builtin shell commands. This allows you to use a disk command which has the same name as a shell builtin without specifying a full pathname. If -n is used, the NAMEs become disabled; otherwise NAMEs are enabled. For example, to use the test found in $PATH instead of the shell builtin version, type enable -n test. On systems supporting dynamic loading, the -f option may be used to load new builtins from the shared object FILENAME. The -d option will delete a builtin previously loaded with -f. If no non-option names are given, or the -p option is supplied, a list of builtins is printed. The -a option means to print every builtin with an indication of whether or not it is enabled. The -s option restricts the output to the POSIX.2 `special' builtins. The -n option displays a list of all disabled builtins.

eval

eval [ARG ...]

Read ARGs as input to the shell and execute the resulting command(s).

exec

exec [-cl] [-a name] file [redirection ...]

Exec FILE, replacing this shell with the specified program. If FILE is not specified, the redirections take effect in this shell. If the first argument is -l, then place a dash in the zeroth arg passed to FILE, as login does. If the -c option is supplied, FILE is executed with a null environment. The -a option means to make set argv[0] of the executed process to NAME. If the file cannot be executed and the shell is not interactive, then the shell exits, unless the shell option execfail is set.

exit

exit [N]

Exit the shell with a status of N. If N is omitted, the exit status is that of the last command executed.

export

export [-nf] [NAME[=value] ...]
export -p

NAMEs are marked for automatic export to the environment of subsequently executed commands. If the -f option is given, the NAMEs refer to functions. If no NAMEs are given, or if -p is given, a list of all names that are exported in this shell is printed. An argument of -n says to remove the export property from subsequent NAMEs. An argument of -- disables further option processing.

false

false

Return an unsuccessful result.

fc

fc [-e ename] [-nlr] [FIRST] [LAST]
fc -s [pat=rep] [cmd]

fc is used to list or edit and re-execute commands from the history list. FIRST and LAST can be numbers specifying the range, or FIRST can be a string, which means the most recent command beginning with that string.

fg

fg [JOB_SPEC]

Place JOB_SPEC in the foreground, and make it the current job. If JOB_SPEC is not present, the shell's notion of the current job is used.

for

for NAME [in WORDS ... ;] do COMMANDS; done

The for loop executes a sequence of commands for each member in a list of items. If in WORDS ...; is not present, then in "$@" is assumed. For each element in WORDS, NAME is set to that element, and the COMMANDS are executed.

function

function NAME { COMMANDS ; }
function NAME () { COMMANDS ; }

Create a simple command invoked by NAME which runs COMMANDS. Arguments on the command line along with NAME are passed to the function as $0 .. $n.

getopts

getopts OPTSTRING NAME [arg]

Getopts is used by shell procedures to parse positional parameters.

hash

hash [-lr] [-p PATHNAME] [-dt] [NAME...]

For each NAME, the full pathname of the command is determined and remembered. If the -p option is supplied, PATHNAME is used as the full pathname of NAME, and no path search is performed. 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, information about remembered commands is displayed.

history

history [-c] [-d OFFSET] [n]
history -ps arg [arg...]
history -awrm [filename]

Display the history list with line numbers. Lines listed with with a * have been modified. Argument of N says to list only the last N lines. The -c option causes the history list to be cleared by deleting all of the entries. The -d option deletes the history entry at offset OFFSET. The -w option writes out the current history to the history file; -r means to read the file and append the contents to the history list instead. -a means to append history lines from this session to the history file. Argument -n means to read all history lines not already read from the history file and append them to the history list.

jobs

jobs [-lnprs] [JOBSPEC ...]
job -x COMMAND [ARGS]

Lists the active jobs. The -l option lists process id's in addition to the normal information; the -p option lists process id's only. If -n is given, only processes that have changed status since the last notification are printed. JOBSPEC restricts output to that job. The -r and -s options restrict output to running and stopped jobs only, respectively. Without options, the status of all active jobs is printed. If -x is given, COMMAND is run after all job specifications that appear in ARGS have been replaced with the process ID of that job's process group leader.

kill

kill [-s sigspec | -n signum | -sigspec] pid | JOBSPEC ...
kill -l [sigspec]

Send the processes named by PID (or JOBSPEC) the signal SIGSPEC. If SIGSPEC is not present, then SIGTERM is assumed. An argument of -l lists the signal names; if arguments follow -l they are assumed to be signal numbers for which names should be listed. Kill is a shell builtin for two reasons: it allows job IDs to be used instead of process IDs, and, if you have reached the limit on processes that you can create, you don't have to start a process to kill another one.

let

let ARG [ARG ...]

Each ARG is an arithmetic expression to be evaluated. Evaluation is done in fixed-width integers with no check for overflow, though division by 0 is trapped and flagged as an error. The following list of operators is grouped into levels of equal-precedence operators. The levels are listed in order of decreasing precedence.

local

local NAME[=VALUE] ...

Create a local variable called NAME, and give it VALUE. local can only be used within a function; it makes the variable NAME have a visible scope restricted to that function and its children.

logout

logout

Logout of a login shell.

popd

popd [+N | -N] [-n]

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

printf

printf [-v var] format [ARGUMENTS]

printf formats and prints ARGUMENTS under control of the FORMAT. 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 means to expand backslash escape sequences in the corresponding argument, and %q means to quote the argument in a way that can be reused as shell input. If the -v option is supplied, the output is placed into the value of the shell variable VAR rather than being sent to the standard output.

pushd

pushd [dir | +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 directory. With no arguments, exchanges the top two directories.

pwd

pwd [-LP]

Print the current working directory. With the -P option, pwd prints the physical directory, without any symbolic links; the -L option makes pwd follow symbolic links.

read

read [-ers] [-u fd] [-t timeout] [-p prompt] [-a array] [-n nchars] [-d delim] [NAME ...]

The given NAMEs are marked readonly and the values of these NAMEs may not be changed by subsequent assignment. If the -f option is given, then functions corresponding to the NAMEs are so marked. If no arguments are given, or if -p is given, a list of all readonly names is printed. The -a option means to treat each NAME as an array variable. An argument of -- disables further option processing.

readonly

readonly [-af] [NAME[=VALUE] ...]
readonly -p

The given NAMEs are marked readonly and the values of these NAMEs may not be changed by subsequent assignment. If the -f option is given, then functions corresponding to the NAMEs are so marked. If no arguments are given, or if -p is given, a list of all readonly names is printed. The -a option means to treat each NAME as an array variable. An argument of -- disables further option processing.

return

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.

select

select NAME [in WORDS ... ;] do COMMANDS; done

The WORDS are expanded, generating a list of words. The set of expanded words is printed on the standard error, each preceded by a number. If in WORDS is not present, in "$@" is assumed. The PS3 prompt is then displayed and a line read from the standard input. If the line consists of the number corresponding to one of the displayed words, then NAME is set to that word. If the line is empty, WORDS and the prompt are redisplayed. If EOF is read, the command completes. Any other value read causes NAME to be set to null. The line read is saved in the variable REPLY. COMMANDS are executed after each selection until a break command is executed.

set

set [--abefhkmnptuvxBCHP] [-o OPTION] [ARG...]

Sets internal shell options.

shift

shift [n]

The positional parameters from $N+1 ... are renamed to $1 ... If N is not given, it is assumed to be 1.

shopt

shopt [-pqsu] [-o long-option] OPTNAME [OPTNAME...]

Toggle the values of variables controlling optional behavior. The -s flag means to enable (set) each OPTNAME; the -u flag unsets each OPTNAME. The -q flag suppresses output; the exit status indicates whether each OPTNAME is set or unset. The -o option restricts the OPTNAMEs to those defined for use with set -o. 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.

source

source FILENAME [ARGS]

Read and execute commands from FILENAME and return. The pathnames in $PATH are used to find the directory containing FILENAME. If any ARGS are supplied, they become the positional parameters when FILENAME is executed.

suspend

suspend [-f]

Suspend the execution of this shell until it receives a SIGCONT signal. The -f if specified says not to complain about this being a login shell if it is; just suspend anyway.

test

test [expr]

Exits with a status of 0 (true) or 1 (false) depending on the evaluation of EXPR. Expressions may be unary or binary. Unary expressions are often used to examine the status of a file. There are string operators as well, and numeric comparison operators.

time

time [-p] PIPELINE

Execute PIPELINE and print a summary of the real time, user CPU time, and system CPU time spent executing PIPELINE when it terminates. The return status is the return status of PIPELINE. The -p option prints the timing summary in a slightly different format. This uses the value of the TIMEFORMAT variable as the output format.

times

times

Print the accumulated user and system times for processes run from the shell.

trap

trap [-lp] [ARG SIGNAL_SPEC ...]

The command ARG is to be read and executed when the shell receives signal(s) SIGNAL_SPEC. If ARG is absent (and a single SIGNAL_SPEC is supplied) or -, each specified signal is reset to its original value. If ARG is the null string each SIGNAL_SPEC is ignored by the shell and by the commands it invokes. If a SIGNAL_SPEC is EXIT (0) the command ARG is executed on exit from the shell. If a SIGNAL_SPEC is DEBUG, ARG is executed after every simple command. If the -p option is supplied then the trap commands associated with each SIGNAL_SPEC are displayed. If no arguments are supplied or if only -p is given, trap prints the list of commands associated with each signal. Each SIGNAL_SPEC is either a signal name in signal.h or a signal number. Signal names are case insensitive and the SIG prefix is optional. trap -l prints a list of signal names and their corresponding numbers. Note that a signal can be sent to the shell with kill -signal $$.

true

true

Return a successful result.

type

type [-afptP] NAME [NAME ...]

Obsolete, see declare.

typeset

typeset [-afFirtx] [-p] name[=value]

Obsolete, see declare.

ulimit

ulimit [-SHacdfilmnpqstuvx] [limit

Ulimit provides control over the resources available to processes started by the shell, on systems that allow such control.

umask

umask [-p] [-S] [MODE]

The user file-creation mask is set to MODE. If MODE is omitted, or if -S is supplied, the current value of the mask is printed. The -S option makes the output symbolic; otherwise an octal number is output. If -p is supplied, and MODE is omitted, the output is in a form that may be used as input. If MODE begins with a digit, it is interpreted as an octal number, otherwise it is a symbolic mode string like that accepted by chmod(1).

unalias

unalias [-a] NAME [NAME ...]

Remove NAMEs from the list of defined aliases. If the -a option is given, then remove all alias definitions.

unset

unset [-f] [-v] [NAME ...]

For each NAME, remove the corresponding variable or function. Given the -v, unset will only act on variables. Given the -f flag, unset will only act on functions. With neither flag, unset first tries to unset a variable, and if that fails, then tries to unset a function. Some variables cannot be unset; also see readonly.

until

until COMMANDS; do COMMANDS; done

Expand and execute COMMANDS as long as the final command in the until COMMANDS has an exit status which is not zero.

wait

wait [N]

Wait for the specified process and report its termination status. If N is not given, all currently active child processes are waited for, and the return code is zero. N may be a process ID or a job specification; if a job spec is given, all processes in the job's pipeline are waited for.

while

while COMMANDS; do COMMANDS; done

Expand and execute COMMANDS as long as the final command in the while COMMANDS has an exit status of zero.