mirror of
https://github.com/fish-shell/fish-shell.git
synced 2024-11-27 03:13:37 +08:00
48 lines
1.7 KiB
ReStructuredText
48 lines
1.7 KiB
ReStructuredText
.. _cmd-trap:
|
|
|
|
trap - perform an action when the shell receives a signal
|
|
=========================================================
|
|
|
|
Synopsis
|
|
--------
|
|
|
|
::
|
|
|
|
trap [OPTIONS] [[ARG] REASON ... ]
|
|
|
|
Description
|
|
-----------
|
|
|
|
``trap`` is a wrapper around the fish event delivery framework. It exists for backwards compatibility with POSIX shells. For other uses, it is recommended to define an :ref:`event handler <event>`.
|
|
|
|
The following parameters are available:
|
|
|
|
- ``ARG`` is the command to be executed on signal delivery.
|
|
|
|
- ``REASON`` is the name of the event to trap. For example, a signal like ``INT`` or ``SIGINT``, or the special symbol ``EXIT``.
|
|
|
|
- ``-l`` or ``--list-signals`` prints a list of signal names.
|
|
|
|
- ``-p`` or ``--print`` prints all defined signal handlers.
|
|
|
|
If ``ARG`` and ``REASON`` are both specified, ``ARG`` is the command to be executed when the event specified by ``REASON`` occurs (e.g., the signal is delivered).
|
|
|
|
If ``ARG`` is absent (and there is a single REASON) or -, each specified signal is reset to its original disposition (the value it had upon entrance to the shell). If ``ARG`` is the null string the signal specified by each ``REASON`` is ignored by the shell and by the commands it invokes.
|
|
|
|
If ``ARG`` is not present and ``-p`` has been supplied, then the trap commands associated with each ``REASON`` are displayed. If no arguments are supplied or if only ``-p`` is given, ``trap`` prints the list of commands associated with each signal.
|
|
|
|
Signal names are case insensitive and the ``SIG`` prefix is optional.
|
|
|
|
The exit status is 1 if any ``REASON`` is invalid; otherwise trap returns 0.
|
|
|
|
Example
|
|
-------
|
|
|
|
|
|
|
|
::
|
|
|
|
trap "status --print-stack-trace" SIGUSR1
|
|
# Prints a stack trace each time the SIGUSR1 signal is sent to the shell.
|
|
|