This is a feature of GNU `getopt`, and I think it's supported by most BSD getopts. It's also recommended behavior by the SUS, see guideline 10: http://pubs.open

This is a feature of GNU `getopt`, and I think it's supported by most BSD getopts. It's also recommended behavior by the SUS, see guideline 10: http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap12.html http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_... So it's not mandated, but it's the behavior of nearly all modern UNIX systems.