I have a process that runs as a daemon forking off child processes when requests come in. To control zombies I have the standard

# Install signal handler for child processes
$SIG{'CHLD'} = sub { while (waitpid(-1,WNOHANG) > 0) {} };
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However, the child processes then have to make a system call and I need to trap the exit code eg..

my $res = system $cmd, $arg;

unless ($res == 0) {
    ...
}
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$? now contains -1 and $! 'No child processes', I understand that this is because of my $SIG{'CHLD'} handler. But how can I get the true exit code and message? I've tried 'local $SIG{'CHLD'} = '' prior to the sys call and that seems to work but looks very clumsy.

What is the best way to get at the exit code?