OS X: strange -psn command line parameter when launched from Finder

Question

Our OS X Java application which is launched by a shell script inside the MyApp.app bundle gets a strange command line parameter -psn_0_989382 when

Answer 1

Mac OS X assigns a unique process serial number ("PSN") to all apps launched via GUI. It's used for identifying various processes and instances of executables.

There's nothing I can really add to the documentation, so the best thing is to read the ProcessSerialNumber section of the Carbon Process Manager Reference (original Apple link is dead; this is a mirror).