set Options

B.5 set Options

Table 2.6 lists the options that can be turned on with the set - arg command. All are initially off except where noted. Full Name s, where listed, are arguments to set that can be used with set -o . The Full Name s braceexpand , histexpand , history , keyword , and onecmd are not available in versions of bash prior to 2.0. Also, in those versions, hashing is switched with -d .

Table B.6. Options to set
Option	Full Name	Meaning
-a	allexport	Export all subsequently defined or modified variables .
-B	braceexpand	The shell performs brace expansion. This is on by default.
-b	notify	Report the status of terminating background jobs immediately.
-C	noclobber	Don't allow redirection to overwrite existing files.
-e	errexit	Exit the shell when a simple command exits with non-zero status. A simple command is a command not part of a while , until , or if ; or part of a && or list; or a command whose return value is inverted by ! .
	emacs	Use emacs -style command-line editing.
-f	noglob	Disable pathname expansion.
-H	histexpand	Enable ! style history substitution. On by default in an interactive shell.
	history	Enable command history. On by default in interactive shells .
-h	hashall	Disable the hashing of commands.
	ignoreeof	Disallow CTRL-D to exit the shell.
-k	keyword	Place keyword arguments in the environment for a command.
-m	monitor	Enable job control (on by default in interactive shells).
-n	noexec	Read commands and check syntax but do not execute them. Ignored for interactive shells.
-P	physical	Do not follow symbolic links on commands that change the current directory. Use the physical directory.
-p	privileged	Script is running in suid mode.
	posix	Change the default behavior to that of POSIX 1003.2 where it differs from the standard.
-t	onecmd	Exit after reading and executing one command.
-u	nounset	Treat undefined variables as errors, not as null.
-v	verbose	Print shell input lines before running them.
	vi	Use vi -style command-line editing.
-x	xtrace	Print commands (after expansions) before running them.
-		Signals the end of options. All remaining arguments are assigned to the positional parameters. -x and -v are turned off. If there are no remaining arguments to set , the positional arguments remain unchanged.
--		With no arguments following, unset the positional parameters. Otherwise, the positional parameters are set to the following arguments (even if they begin with - ).