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.\"     @(#)who.1	8.2 (Berkeley) 12/30/93
.\"
.\" $Id: who.1,v 1.1 1997/10/26 17:12:24 gdr Exp $
.\"
.TH WHO 1 "26 October 1997" GNO "Commands and Applications"
.SH NAME
.BR who
\- display who is logged in
.SH SYNOPSIS
.BR who
.RB [ am
.BR I ]
.RI [ file ]
.SH DESCRIPTION
The utility
.BR who
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.
.LP
Available options:
.RS
.IP "\fBam I\fR"
Returns the invoker's real user name. 
.IP \fIfile\fR
By default,
.BR who
gathers information from the file
.BR /var/run/utmp .
An alternate
.BR file
may be specified which is usually
.BR /var/run/wtmp
(or
.BR /var/run/wtmp.[0-6]
depending on site policy as
.BR wtmp
can grow quite large and daily versions may or may not
be kept around after compression by
.BR ac (8)).
The
.BR wtmp
file contains a record of every login, logout,
crash, shutdown and date change
since
.BR wtmp
was last truncated or
created.
.RE
.LP
If
.BR /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
.BR utmp (5).
.SH FILES
.B /var/run/utmp
.br
.B /var/log/wtmp
.br
.B /var/log/wtmp.[0-6]
.SH SEE ALSO
.BR last (1),
.BR users (1),
.BR getuid (2),
.BR utmp (5)
.SH HISTORY
A
.BR who
command appeared in Version 6 AT&T UNIX.