Why can't I trap ctrl-C in a perl script?

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Level 1

46 points

Why can't I trap ctrl-C in a perl script?

I know this is more a perl question, but it works on every other platform EXCEPT Mac OS X.

I am trying to trap ctrl-C, so the perl script can do an orderly shutdown instead of just breaking, leaving caches unflushed and work unsaved. Here's my code:

$SIG{'INT'} = 'shutdown'; $SIG{'QUIT'} = 'shutdown';

(the bulk of my program here)

sub shutdown {
warn "Flushing caches and shutting down now\n";
&flushcache;
$SIG{'INT'} = 'DEFAULT'; $SIG{'QUIT'} = 'DEFAULT';
$shutdownnow = 1;
exit;
}

When I hit ctrl-C, it ignores ctrl-C and just keeps running. I have to ctrl-Z then go 'kill %1' which of course does not cause it to shut down gently.

Mac OS X (10.5.8)

Posted on Jun 28, 2010 2:17 PM

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Answer 1

BobHarris

Level 9

56,939 points

Jun 28, 2010 2:44 PM in response to Wolf Harper

This works for me.


#!/usr/bin/env perl
$SIG{INT} = sub { print STDERR "Control-C   "; };
$SIG{QUIT} = sub { print STDERR "Control-   "; };
sleep 30;

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Message was edited by: BobHarris

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Answer 2

Jun 28, 2010 3:04 PM in response to Wolf Harper

Probably because you are interrupting the program when it is not inside the main package.

Since you cannot really control that, try using a function pointer, not just the name of the function, e.g:

$SIG{'INT'} = &shutdown;

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Answer 3

Wolf Harper Author

Level 1

46 points

Jun 28, 2010 10:01 PM in response to Robert Jacobson1

Aha! Yes, I had been using a deprecated form (which I think goes back to perl 4). Indeed, my program was spending most of its execution time in a module.

THANK YOU!!

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