I am trying to understand
info who but completly fail at the term »non-option argument«. Can someone please explain this term to me in simple words or an example?
UPDATE: from ' info who' :
If given no non-option arguments, `who' prints the following information for each user currently logged on: login name, terminal line, login time, and remote hostname or X display.
If given one non-option argument,
who' uses that instead of a default system-maintained file (often/var/run/utmp' or
/etc/utmp') as the name of the file containing the record of users logged on./var/log/wtmp' is commonly given as an argument to `who' to look at who has previously logged on.
If given two non-option arguments,
who' prints only the entry for the user running it (determined from its standard input), preceded by the hostname. Traditionally, the two arguments given aream i', as in `who am i'.
I [thought to] know the difference between an argument and an option, but this [again] nixes a lot.