Re^2: protect children from SIG{INT}

Are you sure about that? I don't think that signal handlers persist across an exec (though it seems that the signal mask does; see the below update). They didn't in my short test:

$SIG{INT} = $SIG{HUP} = sub {};
exec qw(/bin/sleep 5)
    or die 'exec failed';
[download]

I was able to interrupt that with CTRL-C, even though I ignored SIGINT in the child process.

Update: Well, the above apparently worked for the OP, though it still doesn't work for me. Maybe it's OS-dependent; I'm testing on Linux.

Update: Kudos to pileofrogs for pointing out below that setting the signal handlers to the string IGNORE works perfectly! It seems that the signal mask persists across an exec, but signal handlers don't, which basically makes sense. So this code works on my system:

$SIG{INT} = $SIG{HUP} = 'IGNORE';
exec qw(sleep 5)
    or die 'exec failed';
[download]

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Re^3: protect children from SIG{INT} by Zaxo (Archbishop) on Nov 18, 2005 at 09:13 UTC
If a sleeping process catches any signal, it doesn't automatically resume sleep after the handler fires. Your process is exiting because it's done. To sleep a specified time in spite of interrupts, you need to be prepared to resume sleep. One way in Perl, `my $span = 5; $span -= sleep $span while $span > 0;` [download] The solution I gave would be improved by doing that wherever `sleep 5` appears. After Compline, Zaxo	[reply] [d/l] [select]
Re^4: protect children from SIG{INT} by QM (Parson) on Nov 18, 2005 at 15:12 UTC
`$span -= sleep $span while $span > 0;` [download] Thanks, I had forgotten that `sleep` returns something useful! -QM -- Quantum Mechanics: The dreams stuff is made of	[reply] [d/l] [select]
Re^4: protect children from SIG{INT} by sgifford (Prior) on Nov 18, 2005 at 16:18 UTC
It still looks to me like the `exec` is the problem: `#!/usr/bin/perl $SIG{INT} = $SIG{HUP} = sub {}; exec 'perl', '-e', '$span=5; $span -= sleep $span while $span > 0; warn "Sleep is done\n";' or die 'exec failed';` [download] Hitting CTRL-C kills the process, and doesn't print `Sleep is done`, as it would if it had completed normally. Of course, using `do` instead would work, because it would avoid the `exec`. Does it even make sense for a signal handler to persist across an `exec`? A signal handler is basically an address in memory that the kernel should cause the user process to jump to if a signal arrives, but after an `exec` the address space will change, and the old address will almost certainly not be a sane place to jump to.	[reply] [d/l] [select]
Re^3: protect children from SIG{INT} by pileofrogs (Priest) on Nov 18, 2005 at 16:57 UTC
Try setting the child's signal handler to 'IGNORE' rather than sub {};	[reply]