MirOS Manual: sigtrap(3p)


sigtrap(3p)     Perl Programmers Reference Guide      sigtrap(3p)

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 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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sigtrap(3p)     Perl Programmers Reference Guide      sigtrap(3p)

     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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sigtrap(3p)     Perl Programmers Reference Guide      sigtrap(3p)

     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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