I noticed by mistake one day this undocumented shorthand for chown:
chown user. filename
Which is the shorthand for:
chown user:user filename
The latter was a real pain to type when running it often, so the shorthand came in very handy. I tried looking for its documentation in the docs but never found a hint about that hidden feature.
Is this a POSIX compliant shorthand? Is it chown that parses it differently or a bash expansion of some sort? I'm using Debian 8.4 but I've been using that for many years already. Is it debian-implementation specific?
Best Answer
Thanks to @JeffSchaller for the answer.
This behavior is specific to GNU coreutils' chown command, and is not a function of bash. Being a GNU utility, it is also not Debian-specific.