Copyright (c) 1990 Regents of the University of California.
All rights reserved. The Berkeley software License Agreement
specifies the terms and conditions for redistribution.

@(#)who.1 6.3 (Berkeley) 06/24/90

.AT 3 who - who is on the system who [ who-file ] [ "am I" ] Who, without any argument, reads the /var/run/utmp file, and lists the login name, terminal name, and login time for each user currently logged into the system. If a single argument is given, who uses that file instead of /var/run/utmp. Typically, that file will be /var/log/wtmp, which contains a record of all the logins, logouts, crashes, shutdowns and time changes since it was created. In either case, each login will be listed with the user name, the terminal name (with "/dev/" suppressed), login date and time, and, if applicable, the host logged in from.

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 output line without any user name. For more information on the special characters, see utmp(5).

With two arguments, as in `who am I' (and also `who are you'), who tells you who you are logged in as.

/var/run/utmp

/var/log/wtmp

last(1), users(1), getuid(2), utmp(5)