nlish stands for the Not Logged In Shell (commonly called the Nobody Shell).
We use this on our system for every terminal, rather than have getty sit
around waiting for users to log in.  This shell is forked by getty and allows
users to access a restricted subset of commands without being logged in
(i.e. df, ss, ps, write, who, date, etc...).

As a consequence of this setup we have made uid 99 permanently the id of
user Nobody.  Since the Nobody shells are always running when no user
is logged in this has caused us to make many normal programs a little smarter
so as to ignore telling about Nobody shells (i.e. who => whom, ss's + option).
