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 Names, where listed, are arguments to set that can be used with set -o. The Full Names 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 -). |