Try using alarm inside an eval: 
eval {
    local $SIG{'ALRM'} = { die("Timeout\n"); };
    alarm(60);
    system('build.sh');
    alarm(0);
};
if ($@ =~ /^Timeout/) {
    die("Build timed out\n");
}

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Remember: There's always one more bug.

In reply to Re: Detecting hung conditions in win32 by jdhedden
in thread Detecting hung conditions in win32 by Zadeh

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