set [+abefhkmnptuvxBCEHPT] [+o option-name] [arg ...]
Without options, the name and value of each shell variable are displayed 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 option processing 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 modified or created for
export to the environment of subsequent commands.
-b Report the status of terminated background jobs immediately, rather than before
the next primary prompt. This is effective only when job control is enabled.
-e Exit immediately if a pipeline (which may consist of a single simple command),
a subshell command enclosed in parentheses, or one of the commands executed as
part of a command list enclosed by braces (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 following the if or elif reserved words, part of any command executed in a
&& or || list except the command following the final && or ||, any command in a
pipeline but the last, or if the command's return value is being inverted with
!. A trap on ERR, if set, is executed before the shell exits. This option
applies to the shell environment and each subshell environment separately (see
COMMAND EXECUTION ENVIRONMENT above), and may cause subshells to exit before
executing all the commands in the subshell.
-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 environ‐
ment 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 inter‐
active shells on systems that support it (see JOB CONTROL above). Background
processes run in a separate process group and a line containing their exit sta‐
tus 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 interactive, unless the shell is started with
the --noediting option. This also affects the editing interface used
for read -e.
errexit Same as -e.
errtrace
Same as -E.
functrace
Same as -T.
hashall Same as -h.
histexpand
Same as -H.
history Enable command history, as described above under HISTORY. This option
is on by default in interactive shells.
ignoreeof
The effect is as if the shell command ``IGNOREEOF=10'' had been exe‐
cuted (see Shell Variables 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 (right‐
most) command to exit with a non-zero status, or zero if all commands
in the pipeline exit successfully. This option is disabled by default.
posix Change the behavior of bash where the default operation differs from
the POSIX standard to match the standard (posix mode).
privileged
Same as -p.
verbose Same as -v.
vi Use a vi-style command line editing interface. This also affects the
editing interface used for read -e.
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 current 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, BASHOPTS, CDPATH, and GLOBIGNORE variables, if they appear in the
environment, are ignored. If the shell is started with the effective user
(group) id not equal to the real user (group) id, and the -p option is not 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 and parameters other than the special parameters "@" and
"*" as an error when performing parameter expansion. If expansion is attempted
on an unset variable or parameter, 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 command, 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 <> redi‐
rection operators. This may be overridden 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 executing commands such
as cd that change the current working directory. It uses the physical direc‐
tory structure instead. By default, bash follows the logical chain of directo‐
ries when performing commands which change the current directory.
-T If set, any traps on DEBUG and RETURN are inherited by shell functions, command
substitutions, and commands executed in a subshell environment. The DEBUG and
RETURN traps are normally not inherited in such cases.
-- If no arguments follow this option, then the positional parameters are unset.
Otherwise, the positional parameters are set to the args, even if some of them
begin with a -.
- Signal the end of options, cause all remaining args to be assigned to the posi‐
tional parameters. The -x and -v options are turned off. If there are no
args, the positional 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.
