login name terminal line login time remote hostname or X display
If given one non-option argument, who uses that instead of /etc/utmp as the name of the file containing the record of users logged on. /etc/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 are `am i', as in `who am i'.