I'm desperately trying to get timeouts to work and came up with this test code: 

use Sys::SigAction qw( set_sig_handler );
eval {
    my $h = set_sig_handler( 'ALRM' ,sub {
        die "TIMEOUT\n";
    }, {
         mask=>[ 'ALRM' ],
         safe=>1,
    });
    eval {
        alarm 3;
        $opened= open my $check, '-|', 'sleep 60';
        if ($opened) {
            # slurp its output
            $line= do { local $/; <$check>; };
            $exit_code= $!+0;
            $closed= close $check;
        }
        alarm 0;
    };
    alarm 0;
    die $@ if $@;
};
alarm 0;
print $@;

[download]
Of course I can't really ready something from a "sleep" command, But I expected this to return after 3 seconds with a "Timeout". Instead I have to wait 60 seconds, so the full sleep-time.

I also tried a different command than "sleep" like, for example, a long running "find" command but still the sleep does not die.

What am I doing wrong or what do I misunderstand?

s$$([},&%#}/&/]+}%&{})*;#$&&s&&$^X.($'^"%]=\&(|?*{%
+.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e

In reply to trying to get timeout to work by Skeeve

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