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.\"     @(#)who.1	8.2 (Berkeley) 12/30/93
.\"
.Dd July 22, 2005
.Dt WHO 1
.Os
.Sh NAME
.Nm who
.Nd display who is logged in
.Sh SYNOPSIS
.Nm
.Op Fl HmqsTu
.Op Ar file
.Nm
.Ar am i
.Sh DESCRIPTION
The
.Nm
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.
.Pp
Available options:
.Pp
.Bl -tag -width file
.It Fl H
Write column headings above the regular output.
.It Fl m
Only print information about the current terminal.
This is the
.Tn POSIX
way of saying
.Nm
.Ar am i .
.It Fl q
.Dq Quick mode :
List only the names and the number of users currently logged on.
When this option is used, all other options are ignored.
.It Fl s
List only the name, line and time fields.
This is the default.
.It Fl T
Print a character after the user name indicating the state of the
terminal line:
.Sq +
if the terminal is writable;
.Sq -
if it is not;
and
.Sq \&?
if a bad line is encountered.
.It Fl u
Print the idle time for each user.
.It Ar \&am I
Returns the invoker's real user name.
.It Ar file
By default,
.Nm
gathers information from the file
.Pa /var/run/utmp .
An alternative
.Ar file
may be specified which is usually
.Pa /var/log/wtmp
(or
.Pa /var/log/wtmp.[0-6]
depending on site policy as
.Pa wtmp
can grow quite large and daily versions may or may not
be kept around after compression by
.Xr ac 8 ) .
The
.Pa wtmp
file contains a record of every login, logout,
crash, shutdown and date change
since
.Pa wtmp
was last truncated or
created.
.El
.Pp
If
.Pa /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
.Xr utmp 5 .
.Sh FILES
.Bl -tag -width /var/log/wtmp.[0-6] -compact
.It Pa /var/run/utmp
.It Pa /var/log/wtmp
.It Pa /var/log/wtmp.[0-6]
.El
.Sh SEE ALSO
.Xr last 1 ,
.Xr mesg 1 ,
.Xr users 1 ,
.Xr getuid 2 ,
.Xr utmp 5 ,
.Xr utmpx 5
.Sh STANDARDS
The
.Nm
utility is expected to conform to
.St -p1003.2-92 .
.Sh HISTORY
A
.Nm
utility appeared in
.At v6 .