Provided by: perl-doc_5.38.2-5_all 
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 three 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 any 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);