V10/man/man1/who.1

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.TH WHO 1
.CT 1 comm_users sa_mortals
.SH NAME
who, whois, last \- who is or was on the system
.SH SYNOPSIS
.B who
[
.B -i
]
[
.I who-file
]
.PP
.B who am i
.PP
.B whois
.I username
.PP
.B last
[
.B -f
.I who-file
]
[
.I userid ...
]
[
.I terminal
]
.SH DESCRIPTION
.I Who,
without an argument,
lists the login name, terminal name, and login time
for each current user.
With the
.B -i
option, the report includes the number of minutes
that the user's terminal has been idle.
.PP
With two arguments,
as in
.LR "who am i" ,
.I who
tells who you are logged in as.
.PP
Without an argument,
.I who
examines the
.F /etc/utmp
file to obtain its information.
If a file is given, that file is examined.
Typically the given file will be
.FR /usr/adm/wtmp ,
which contains a record of all the logins since it
was created.
Then
.I who
lists
logins, logouts, and crashes since the creation of
the wtmp file.
Each login is listed with user name,
terminal name (with
.L /dev/
suppressed),
and date and time.
When an argument is given, logouts produce a similar line without a user name.
Reboots produce a line with 
.L x
in the place of the device name,
and a fossil time indicative of when the system went down.
.PP
.I Whois
consults administrative files to identify the
.I username.
(Actually,
.I whois
uses
.IR grep
and can locate information by any useful key, such
as real name or telephone number.)
.PP
.I Last
reports logins and logouts in reverse chronological order.
Optional arguments restrict attention to selected userids or
terminals.
Terminals
.BR tty0 ", " tty1 ", ..."
may be abbreviated
.BR 0 ", " 1 ", ..."
.PP
By default,
.I last
examines the list of logins and logouts in
.FR /usr/adm/wtmp ;
option
.B -f
specifies a different file.
.PP
.I Last
reports userid, terminal,
time on, and time off for all users, or for selected
.IR userids.
A pseudo-user,
.LR reboot ,
is logged in at reboots of the system.
.PP
Upon interrupt,
.I last
tells how far back it has looked;
upon quit 
.RB (control- \e )
it tells how far and keeps on looking.
.SH EXAMPLES
.TP
.B last reboot
Report recent system outages.
.SH FILES
.F /etc/utmp
.br
.F /usr/adm/wtmp
.br
.F /usr/adm/usrlist
.br
.F /etc/passwd
.SH "SEE ALSO"
.IR getuid (1), 
.IR getuid (2), 
.IR utmp (5), 
.IR ac (8),
.IR tty (1),
.IR vwhois
in
.IR vismon (9.1)