[crimbles]

Depends really. If it's some kind of runtime or VM you pretty much have zero idea what the exit code was. Python, CLR, JVM tend to leave you in this mire.

[GTP]

Yes, but remember that usually nowadays a piece of software also logs something to stderr instead of relying just on exit codes to signal error.

[crimbles]

Not necessarily. Most of the 139's I get these days are SIGSEGV related. Obviously if you annoy the MMU at that level it's not going to get given an opportunity to write anything useful to stderr.