trap(1)

NAME
trap -- perform an action when the shell receives a signal

  Synopsis

trap [OPTIONS] [[ARG] SIGSPEC ... ]

  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 event handler.

The following parameters are available:

•   ARG is the command to be executed on signal delivery.

•   SIGSPEC is the name of the signal to trap.

•   -l or --list-signals prints a list of signal names.

•   -p or --print prints all defined signal handlers.

If ARG and SIGSPEC are both specified, ARG is the command to be executed when the signal specified by SIGSPEC is delivered.

If ARG is absent (and there is a single SIGSPEC) 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 SIGSPEC 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 SIGSPEC 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 return status is 1 if any SIGSPEC 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.