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

Thesigtrap pragma is a simple interface to installing signal handlers. You can have it install one of two handlers supplied bysigtrap itself (one which provides a Perl stack trace and one which simplydie()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 three lists of signals to trap, plus you can supply your own list of signals.

The arguments passed to theuse statement which invokessigtrap are processed in order. When a signal name or the name of one ofsigtrap'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 callsdie (actuallycroak) with a message indicating which signal was caught.

handleryour-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. Seeperlvar 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 oldsigtrap interface, they are ABRT, BUS, EMT, FPE, ILL, PIPE, QUIT, SEGV, SYS, TERM, and TRAP. If no signals or signals lists are passed tosigtrap, 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 tellssigtrap to install handlers only for subsequently listed signals which aren't already trapped or ignored.

any

This token tellssigtrap 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 thatsigtrap should install a handler for that name.

number

Require that at least versionnumber ofsigtrap 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 any of thenormal-signals which is currentlyuntrapped, provide a stack trace on receipt ofany of theerror-signals:

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

Install my_handler() as the handler for thenormal-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);