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| Appendix B Reference Lists |

## B.5 Options

These are options that can be turned on with the set -o command. All are initially off except where noted. Abbrevs, where listed, are arguments to set that can be used instead of the full set -o command (e.g., set -a is an abbreviation for set -o allexport). The abbreviations are actually backward-compatible Bourne shell options.

Option | Abbrev | Meaning
--- | --- | ---
allexport | -a | Export all subsequently defined variables.
errexit | -e | Exit the shell when a command exits with non-0 status.
bgnice |  | Run all background jobs at decreased priority (on by default).
emacs |  | Use emacs-style command-line editing.
gmacs |  | Use emacs-style command-line editing, but with a slightly different meaning for `[CTRL-T]` (See Chapter 2, Command-line Editing).
ignoreeof |  | Disallow `[CTRL-D]` to exit the shell.
markdirs |  | Add / to all directory names generated from wildcard expansion.
monitor | -m | Enable job control (on by default).
noclobber |  | 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.
nounset | -u | Treat undefined variables as errors, not as null.
privileged | -p | Script is running in suid mode.
trackall | -h | Substitute full pathnames for commands in alias expansions.
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.
xtrace | -x | Print commands (after expansions) before running them.

B.4 Test Operators |  | B.6 Typeset Options