# sigtrap - phpMan

## NAME
    sigtrap - Perl pragma to enable simple signal handling

## SYNOPSIS
        use sigtrap;
        use sigtrap qw(stack-trace old-interface-signals);  # equivalent
        use sigtrap qw(BUS SEGV PIPE ABRT);
        use sigtrap qw(die INT QUIT);
        use sigtrap qw(die normal-signals);
        use sigtrap qw(die untrapped normal-signals);
        use sigtrap qw(die untrapped normal-signals
                        stack-trace any error-signals);
        use sigtrap 'handler' => \&my_handler, 'normal-signals';
        use sigtrap qw(handler my_handler normal-signals
                        stack-trace error-signals);

## DESCRIPTION
    The sigtrap pragma is a simple interface to installing signal handlers.
    You can have it install one of two handlers supplied by sigtrap itself
    (one which provides a Perl stack trace and one which simply "die()"s),
    or alternately you can supply your own handler for it to install. It can
    be told only to install a handler for signals which are either untrapped
    or ignored. It has a couple of lists of signals to trap, plus you can
    supply your own list of signals.

    The arguments passed to the "use" statement which invokes sigtrap are
    processed in order. When a signal name or the name of one of sigtrap's
    signal lists is encountered a handler is immediately installed, when an
    option is encountered it affects subsequently installed handlers.

## OPTIONS
  SIGNAL HANDLERS
    These options affect which handler will be used for subsequently
    installed signals.

    stack-trace
        The handler used for subsequently installed signals outputs a Perl
        stack trace to STDERR and then tries to dump core. This is the
        default signal handler.

    die The handler used for subsequently installed signals calls "die"
        (actually "croak") with a message indicating which signal was
        caught.

    handler *your-handler*
        *your-handler* will be used as the handler for subsequently
        installed signals. *your-handler* can be any value which is valid as
        an assignment to an element of %SIG. See perlvar for examples of
        handler functions.

  SIGNAL LISTS
    sigtrap has a few built-in lists of signals to trap. They are:

    normal-signals
        These are the signals which a program might normally expect to
        encounter and which by default cause it to terminate. They are HUP,
        INT, PIPE and TERM.

    error-signals
        These signals usually indicate a serious problem with the Perl
        interpreter or with your script. They are ABRT, BUS, EMT, FPE, ILL,
        QUIT, SEGV, SYS and TRAP.

    old-interface-signals
        These are the signals which were trapped by default by the old
        sigtrap interface, they are ABRT, BUS, EMT, FPE, ILL, PIPE, QUIT,
        SEGV, SYS, TERM, and TRAP. If no signals or signals lists are passed
        to sigtrap, this list is used.

    For each of these three lists, the collection of signals set to be
    trapped is checked before trapping; if your architecture does not
    implement a particular signal, it will not be trapped but rather
    silently ignored.

  OTHER
    untrapped
        This token tells sigtrap to install handlers only for subsequently
        listed signals which aren't already trapped or ignored.

    any This token tells sigtrap to install handlers for all subsequently
        listed signals. This is the default behavior.

    *signal*
        Any argument which looks like a signal name (that is,
        "/^[A-Z][A-Z0-9]*$/") indicates that sigtrap should install a
        handler for that name.

    *number*
        Require that at least version *number* of sigtrap is being used.

## EXAMPLES
    Provide a stack trace for the old-interface-signals:

        use sigtrap;

    Ditto:

        use sigtrap qw(stack-trace old-interface-signals);

    Provide a stack trace on the 4 listed signals only:

        use sigtrap qw(BUS SEGV PIPE ABRT);

    Die on INT or QUIT:

        use sigtrap qw(die INT QUIT);

    Die on HUP, INT, PIPE or TERM:

        use sigtrap qw(die normal-signals);

    Die on HUP, INT, PIPE or TERM, except don't change the behavior for
    signals which are already trapped or ignored:

        use sigtrap qw(die untrapped normal-signals);

    Die on receipt one of an of the normal-signals which is currently
    untrapped, provide a stack trace on receipt of any of the error-signals:

        use sigtrap qw(die untrapped normal-signals
                        stack-trace any error-signals);

    Install my_handler() as the handler for the normal-signals:

        use sigtrap 'handler', \&my_handler, 'normal-signals';

    Install my_handler() as the handler for the normal-signals, provide a
    Perl stack trace on receipt of one of the error-signals:

        use sigtrap qw(handler my_handler normal-signals
                        stack-trace error-signals);