Yet another example for you... (not that you need another, though)

I do the following for one of my mod_perl apps in which I use warn to output debugging & status information to Apaches error_log:

$SIG{__WARN__} = sub {
    $msg = undef;
    foreach (@_) { 
        $msg =~ s/ at.*$// unless $msg =~ /(uninit|deprec)/; 
    } 
    print STDERR 'MyApp...' . $msg;
}
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Where I really only want to see the line number if it's an uninitialized or deprecated warning message. One could very easily add a timestamp to this, too.