Options (Learning the Korn Shell, 2nd Edition)

B.6. Options

These are options that can be turned on with the set -o command. All are initially off except where noted. Abbreviations, where listed, are options to set that can be used instead of the full set -o command (e.g., set -a is an abbreviation for set -o allexport). For the most part, the abbreviations are actually backward-compatible Bourne shell options. To disable an option, use set +o long-name or set +X, where long-name and X are the long form or the single character form of the option, respectively.

Option	Abbrev	Meaning
allexport	`-a`	Export all subsequently defined variables.
bgnice		Run all background jobs at decreased priority (on by default).
emacs		Use Emacs-style command-line editing.
errexit	`-e`	Exit the shell when a command exits with nonzero status.
gmacs		Use Emacs-style command-line editing, but with a slightly different meaning for CTRL-T (See Chapter 2).
ignoreeof		Disallow CTRL-D to exit the shell.
keyword	`-k`	Execute assignments in the middle of command lines. (Very obsolete.)
markdirs		Add / to all directory names generated from wildcard expansion.
monitor	`-m`	Enable job control (on by default).
noclobber	`-C`	Don't allow `>` redirection to existing files.
noexec	`-n`	Read commands and check for syntax errors, but don't execute them.
noglob	`-f`	Disable wildcard expansion.
nolog		Disable command history for function definitions.
notify	`-b`	Print job completion messages right away, instead of waiting for next prompt.
nounset	`-u`	Treat undefined variables as errors, not as null.
pipefail		Wait for all jobs in a pipeline to complete. Exit status is that of last command that failed, or zero otherwise. (ksh93g and later.)
privileged	`-p`	Script is running in suid mode.
trackall	`-h`	Create an alias for each full pathname found in a command search. (ksh93 ignores this option; the behavior is always on, even if this option is turned off.)
verbose	`-v`	Print commands (verbatim) before running them.
vi		Use vi-style command-line editing.
viraw		Use vi-mode and have each keystroke take effect immediately. (This is required on some very old systems for vi-mode to work at all, and is necessary on all systems in order to use TAB for completion. Starting with ksh93n, it is automatically enabled when vi-mode is being used.)
xtrace	`-x`	Print commands (after expansions) before running them.

The set command has a few additional options that don't have corresponding set -o versions, as follows:

Option	Meaning
`set -A` ...	Indexed array assignment.
`set -s`	Sort the positional parameters.
`set -t`	Read and execute one command, and then exit. (Obsolete.)