= Shell Options =

The shell can be configured with the `set` and `unset` [[Shell/BuiltinCommands#Set|builtins]]. To inspect the enabled options, use the `$SHELLOPTS` [[Shell/ShellVariables#Not_Useful|shell variable]].

<<TableOfContents>>

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== Expansion ==

If `noglob` is enabled, [[Shell/Expansion#Filename_Expansion|filename expansion]] is not applied.

{{{
set -f #or: set -o noglob
set +f
}}}

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== Interactive Shells ==

If `vi` is enabled, [[Vim|vi]]-style cursor movement commands can be used on the command prompt.

{{{
set -o vi
}}}

If `notify` is enabled, the status of terminated background jobs is printed immediately, as opposed to before printing the next prompt.

{{{
set -b #or: set -o notify
set +b
}}}

If `ignoreeof` is enabled, an interactive shell will not exit upon receipt of an `EOF` character.

{{{
set -o ignoreeof
}}}

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== Job Control ==

If `monitor` is enabled, job control (i.e. background processes) is used.

{{{
set -m #or: set -o monitor
set +m
}}}

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== Programming ==

If `verbose` is enabled, commands are printed before executing.

{{{
set -v #or: set -o verbose
set +v
}}}

If `allexport` is enabled, all variables that are created or modified are set to export.

{{{
set -a #or: set -o allexport
set +a
}}}



=== Errors ===

If `errexit` is enabled, a command returning an error code will cause the shell to exit in most circumstances. The exceptions are:

 * The test command(s) in `while` or `until` [[Shell/Looping|loops]]
 * The test command(s) in `if` [[Shell/Logic|conditional logic]]
 * Any command followed by `&&` or `||`, or preceded by `!`
 * [[Shell/Expansion#Command_Expansion|Command substitutions]]
 * Any command in a [[Shell/Pipeline|pipeline]] except the last

{{{
set -e #or: set -o errexit
set +e
}}}

If `nounset` is enabled, accessing an unset variable raises an error.

{{{
set -u #or: set -o nounset
set +u
}}}

If `noclobber` is enabled, output redirection with `>`, `>&`, and `<>` will raise an error rather than overwrite a file.

{{{
set -C #or: set -o noclobber
set +C
}}}

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== Testing ==

If `noexec` is enabled, no commands will be executed.

{{{
set -n #or: set -o noexec
set +n
}}}

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== Tracing ==

If `xtrace` is enabled, simple commands as well as [[Shell/Looping|looping commands]] (and all arguments to these commands) are printed before execution.

{{{
set -x #or: set -o xtrace
set +x
}}}



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CategoryRicottone