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cf2ca56e34
This teaches `--on-signal SIGINT` (and by extension `trap cmd SIGINT`) to work properly in scripts, not just interactively. Note any such function will suppress the default behavior of exiting. Do this for SIGTERM as well.
54 lines
1.9 KiB
ReStructuredText
54 lines
1.9 KiB
ReStructuredText
.. _cmd-trap:
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trap - perform an action when the shell receives a signal
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=========================================================
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Synopsis
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--------
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.. synopsis::
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trap [OPTIONS] [[ARG] REASON ... ]
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Description
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-----------
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``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>`.
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The following parameters are available:
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*ARG*
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Command to be executed on signal delivery.
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*REASON*
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Name of the event to trap. For example, a signal like ``INT`` or ``SIGINT``, or the special symbol ``EXIT``.
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**-l** or **--list-signals**
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Prints a list of signal names.
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**-p** or **--print**
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Prints all defined signal handlers.
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**-h** or **--help**
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Displays help about using this command.
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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).
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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.
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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.
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Signal names are case insensitive and the ``SIG`` prefix is optional. Trapping a signal will prevent fish from exiting in response to that signal.
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The exit status is 1 if any *REASON* is invalid; otherwise trap returns 0.
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Example
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-------
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::
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trap "status --print-stack-trace" SIGUSR1
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# Prints a stack trace each time the SIGUSR1 signal is sent to the shell.
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