You have a zombie problem. Call wait before exit in the signal handler.

You don't say what version of perl you use, but "safe" signals might be involved. That could prevent Ctrl-C from interrupting a blocking read in <CMD>. Your code looks fine.

You can break up the print <CMD>; by calling sysread, perhaps inside select. 

# replaces print <CMD>;
vec( my $rin, fileno(*CMD), 1) = 1;
while (select my $rd = $rin, undef, undef, undef;) {
    my $bytes = sysread *CMD, my $buf, 4096;
    print $buf if 0 < $bytes;
    last if 1 > $bytes;
}

# wait added to lay the zombies
sub myhand() {
   print "Parent $$ caught SIGINT.\n";
   print "Parent $$ will KILL $pid.\n";

   kill INT, $pid;
   waitpid $pid;
   exit 0;
}

[download]
It's a potential problem that the signal handler is set before the child is launched. That makes the child inherit a handler that is clearly meant for the parent. If you changed the kill signal to the more proper SIGINT, the child would try to signal a nonexistent child.

After Compline,
Zaxo

In reply to Re: SIGINT and system calls by Zaxo
in thread SIGINT and system calls by Anonymous Monk

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