sigtrap(3p) Perl Programmers Reference Guide sigtrap(3p)NAMEsigtrap - 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 sig-
nal 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 encoun-
tered it affects subsequently installed handlers.
OPTIONS
SIGNAL HANDLERS
These options affect which handler will be used for subse-
quently installed signals.
stack-trace
The handler used for subsequently installed signals out-
puts 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 subse-
quently installed signals. your-handler can be any
value which is valid as an assignment to an element of
%SIG.
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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 sig-
nals 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 architec-
ture 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;
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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);
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