WHO(1) BSD General Commands Manual WHO(1)
who -- display who is on the system
who [-HmqsTu] [am I] [file]
The who utility displays information about currently logged in users. By default, this
includes the login name, tty name, date and time of login and remote hostname if not local.
The options are as follows:
-H Write column headings above the output.
-m Show information about the terminal attached to standard input only.
-q ``Quick mode'': List the names and number of logged in users in columns. All other
command line options are ignored.
-s Show the name, line and time fields only. This is the default.
-T Indicate whether each user is accepting messages. One of the following characters
+ User is accepting messages.
- User is not accepting messages.
? An error occurred.
-u Show idle time for each user in hours and minutes as hh:mm, '.' if the user has been
idle less that a minute, and ``old'' if the user has been idle more than 24 hours.
am I Equivalent to -m.
By default, who gathers information from the file /var/run/utmp. An alternate file may be
specified which is usually /var/log/wtmp (or /var/log/wtmp.[0-6] depending on site policy as
wtmp can grow quite large and daily versions may or may not be kept around after compression
by ac(8)). The wtmp file contains a record of every login, 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 output line without any user name. For
more information on the special characters, see utmp(5).
The COLUMNS, LANG, LC_ALL and LC_TIME environment variables affect the execution of who as
described in environ(7).
The who utility exits 0 on success, and >0 if an error occurs.
last(1), users(1), w(1), utmp(5)
The who utility conforms to IEEE Std 1003.1-2001 (``POSIX.1'').
A who command appeared in Version 1 AT&T UNIX.
BSD May 8, 2002 BSD