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Man Pages


Manual Reference Pages  -  SIGTRAP (3)

.ds Aq ’

NAME

sigtrap - Perl pragma to enable simple signal handling

CONTENTS

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 <B>sigtrapB> pragma is a simple interface to installing signal handlers. You can have it install one of two handlers supplied by <B>sigtrapB> 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 <B>sigtrapB> are processed in order. When a signal name or the name of one of <B>sigtrapB>’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.
<B>stack-traceB> 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.
<B>dieB> The handler used for subsequently installed signals calls die (actually croak) with a message indicating which signal was caught.
<B>handlerB> 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

<B>sigtrapB> has a few built-in lists of signals to trap. They are:
<B>normal-signalsB> 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.
<B>error-signalsB> 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.
<B>old-interface-signalsB> These are the signals which were trapped by default by the old <B>sigtrapB> interface, they are ABRT, BUS, EMT, FPE, ILL, PIPE, QUIT, SEGV, SYS, TERM, and TRAP. If no signals or signals lists are passed to <B>sigtrapB>, 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

<B>untrappedB> This token tells <B>sigtrapB> to install handlers only for subsequently listed signals which aren’t already trapped or ignored.
<B>anyB> This token tells <B>sigtrapB> 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 <B>sigtrapB> should install a handler for that name.
number Require that at least version number of <B>sigtrapB> 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 an of the <B>normal-signalsB> which is currently <B>untrappedB>, provide a stack trace on receipt of <B>anyB> of the <B>error-signalsB>:



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



Install my_handler() as the handler for the <B>normal-signalsB>:



    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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perl v5.22.1 SIGTRAP (3) 2015-10-17

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