WHO(1) BSD Reference Manual WHO(1)
who - display who is logged in
who [am I] [file]
The utility who displays a list of all users currently logged on, showing
for each user the login name, tty name, the date and time of login, and
hostname if not local.
am I Returns the invoker's real user name.
file By default, who gathers information from the file /var/run/utmp. An
alternate file may be specified which is usually /var/run/wtmp (or
/var/run/wtmp.[0-6] depending on site policy as wtmp can grow quite
large and daily versions may or may not be kept around after com-
pression by ac(8)). The wtmp file contains a record of every lo-
gin, logout, crash, shutdown and date change since wtmp was last
truncated or created.
If /var/log/wtmp is being used as the file, the user name may be empty or
one of the special characters '|', '}' and '~'. Logouts produce an out-
put line without any user name. For more information on the special
characters, see utmp(5).
last(1), users(1), getuid(2), utmp(5)
A who command appeared in Version 6 AT&T UNIX.
4.4BSD December 30, 1993 1