Guideline 3 in http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap12.html#tag_12_02 http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_...

Guideline 3 in http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap12.html#tag_12_02 http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_... suggests that multiple characters after a single dash should be multiple arguments. And, for example, GNU chose a different syntax ( --foo=bar ) for long options. (edited to clarify that I actually don't know historically why they chose that)