sigtrap - Perl pragma to enable simple signal handling
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);
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 dies), 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.
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.
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.
- 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.
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);