MAN page from Old RedHat 5.X perl-5.004-4.i386.rpm

sigtrap

Section: Perl Programmers Reference Guide (3)
Updated: perl 5.004, patch 04
Index

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 signalhandlers. You can have it install one of two handlers supplied bysigtrap itself (one which provides a Perl stack trace and one whichsimply die()s), or alternately you can supply your own handler for itto install. It can be told only to install a handler for signals whichare either untrapped or ignored. It has a couple of lists of signals totrap, plus you can supply your own list of signals.

The arguments passed to the use statement which invokes sigtrapare processed in order. When a signal name or the name of one ofsigtrap's signal lists is encountered a handler is immediatelyinstalled, when an option is encountered it affects subsequentlyinstalled handlers.

OPTIONS

SIGNAL HANDLERS

These options affect which handler will be used for subsequentlyinstalled signals.

stack-trace: The handler used for subsequently installed signals outputs a Perl stacktrace to STDERR and then tries to dump core. This is the default signalhandler.
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 installedsignals. your-handler can be any value which is valid as anassignment to an element of %SIG.

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 encounterand which by default cause it to terminate. They are HUP, INT, PIPE andTERM.
error-signals: These signals usually indicate a serious problem with the Perlinterpreter 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 betrapped is checked before trapping; if your architecture does notimplement a particular signal, it will not be trapped but rathersilently ignored.

OTHER

untrapped: This token tells sigtrap to install handlers only for subsequentlylisted signals which aren't already trapped or ignored.
any: This token tells sigtrap to install handlers for all subsequentlylisted 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 ahandler 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 forsignals 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 currentlyuntrapped, provide a stack trace on receipt of any of theerror-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 aPerl stack trace on receipt of one of the error-signals:

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

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