who is logged in
utility 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.
The options are as follows:
- Write column headings above the regular output.
- Only print information about the current terminal. This is
the POSIX way of saying who
- (Quick.) List only the names and the number of users
currently logged on. When this option is used, all other options are
- Print a character after the user name indicating the state
of the terminal line: ‘+’ if the terminal is writable;
‘-’ if it is not; and ‘?’ if a bad line is
- Print the idle time for each user.
- Returns the invoker's real user name.
- 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
wtmp file contains a record of every login,
logout, crash, shutdown and date change since
wtmp was last truncated or created.
is being used as the file, the
user name may be empty or one of the special characters
’. Logouts produce an output line
without any user name. For more information on the special characters, see
utility exits 0 on success,
and >0 if an error occurs.
utility is compliant with the
IEEE Std 1003.1-2008
The flags [-abdHlpqrst
marked by IEEE Std 1003.1-2008
as being an X/Open System Interfaces option.
Of these, [-abdlprst
not supported by this implementation of who
utility appeared in
Version 1 AT&T UNIX