Setting signal handlers

andyford has asked for the wisdom of the Perl Monks concerning the following question:

Why is signal handling so ugly? Surely there's a good reason? Is there a better way to do this? For instance, why do I have to define a SigSet object that I never do anything with?

my $sigset = POSIX::SigSet->new();
my $restart_action = POSIX::SigAction->new('restart',$sigset,POSIX::SA
+_NODEFER());
my $end_action = POSIX::SigAction->new('end',$sigset,POSIX::SA_NODEFER
+());
POSIX::sigaction(POSIX::SIGQUIT(), $end_action);
POSIX::sigaction(POSIX::SIGHUP(), $restart_action);
POSIX::sigaction(POSIX::SIGPIPE(), $restart_action);
POSIX::sigaction(POSIX::SIGTERM(), $end_action);
POSIX::sigaction(POSIX::SIGINT(), $restart_action);
POSIX::sigaction(POSIX::SIGUSR1(), $end_action);
[download]

Comment on Setting signal handlers Download Code

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Re: Setting signal handlers by Hue-Bond (Priest) on May 09, 2006 at 20:55 UTC
That's the POSIX way to do things. It's as ugly in Perl as it's in C, since in C it's also done a la POSIX. Fortunately in Perl we have Another Way To Do It: `sub interrupt { print "quitting!\n"; } $SIG{'INT'} = 'interrupt'; sleep 20; __END__ ^C quitting!` [download] -- David Serrano	[reply] [d/l]
Re^2: Setting signal handlers by andyford (Curate) on May 09, 2006 at 21:17 UTC
Thanks David but I tried that first and it didn't work. Supposedly it's because "POSIX unmasks the sigprocmask properly". Not sure what that means, but the POSIX way works and the Perl way doesn't.	[reply]
Re^3: Setting signal handlers by Hue-Bond (Priest) on May 09, 2006 at 21:48 UTC
What did you try exactly? Without some code it's difficult to guess why it's not working for you. You should post a small complete program that shows the problem and tell us what do you expect and what is happening instead. -- David Serrano	[reply]
Re^3: Setting signal handlers by ruoso (Curate) on May 09, 2006 at 21:52 UTC
Well, back in 2000, I gave up on a module (Server::FastPL, now on backpan) because of lost signals and unix sockets constant lock up... My experience told me to not trust signals for anything really important... I did use the $SIG way... maybe the problem is related... daniel	[reply]
Re^4: Setting signal handlers by dave_the_m (Monsignor) on May 09, 2006 at 22:01 UTC
Re^5: Setting signal handlers by ruoso (Curate) on May 09, 2006 at 23:18 UTC
Some notes below your chosen depth have not been shown here
Re: Setting signal handlers by jesuashok (Curate) on May 10, 2006 at 05:52 UTC
Hi > why do I have to define a SigSet object that I never do anything with? Here it goes. Create a new SigSet object. This object will be destroyed automatically when it is no longer needed. Arguments may be supplied to initialize the set. Create an empty set. `$sigset = POSIX::SigSet->new;` [download] Add a signal to a SigSet object. `$sigset->addset( &POSIX::SIGUSR2 );` [download] For more information on SigSet "Keep pouring your ideas"	[reply] [d/l] [select]