NAME
who - who is on the system

SYNOPSIS
who [ who-file ] [ am I ]

DESCRIPTION
Who, without any argument, reads the /etc/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 /etc/utmp. Typically, that file will be
/usr/adm/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 /usr/adm/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.

FILES
/etc/utmp
/usr/adm/wtmp

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