builtin help trap

[shoebill]

trap: trap [-lp] [[arg] signal_spec ...]
    Trap signals and other events.

    Defines and activates handlers to be run when the shell receives signals
    or other conditions.

    ARG is a command to be read and executed when the shell receives the
    signal(s) SIGNAL_SPEC.  If ARG is absent (and a single SIGNAL_SPEC
    is supplied) or `-', each specified signal is reset to its original
    value.  If ARG is the null string each SIGNAL_SPEC is ignored by the
    shell and by the commands it invokes.

    If a SIGNAL_SPEC is EXIT (0) ARG is executed on exit from the shell.  If
    a SIGNAL_SPEC is DEBUG, ARG is executed before every simple command.  If
    a SIGNAL_SPEC is RETURN, ARG is executed each time a shell function or a
    script run by the . or source builtins finishes executing.  A SIGNAL_SPEC
    of ERR means to execute ARG each time a command's failure would cause the
    shell to exit when the -e option is enabled.

    If no arguments are supplied, trap prints the list of commands associated
    with each signal.

    Options:
      -l        print a list of signal names and their corresponding numbers
      -p        display the trap commands associated with each SIGNAL_SPEC

    Each SIGNAL_SPEC is either a signal name in <signal.h> or a signal number.
    Signal names are case insensitive and the SIG prefix is optional.  A
    signal may be sent to the shell with "kill -signal $$".

    Exit Status:
    Returns success unless a SIGSPEC is invalid or an invalid option is given.