WHO(C) UNIX System V
Name
who - lists who is on the system
Syntax
who [-uATHldtasqbrp] [ file ]
who am i
who am I
Description
who can list the user's name, terminal line, login time, and
the elapsed time since activity occurred on the line; it
also lists the process ID of the command interpreter (shell)
for each current user. It examines the /tcb/files/inittab
file to obtain information for the Comments column, and
/etc/utmp to obtain all other information. If file is
given, that file is examined. Usually, file will be
/etc/wtmp, which contains a history of all the logins since
the file was last created.
who with the am i or am I option identifies the invoking
user.
Except for the default -s option, the general format for
output entries is:
name [state] line time activity pid [comment] [exit]
With options, who can list logins, logoffs, reboots, and
changes to the system clock, as well as other processes
spawned by the init process. These options are:
-u This option lists only those users who are currently
logged in. The name is the user's login name. The
line is the name of the line as found in the directory
/dev. The time is the time that the user logged in.
The activity is the number of hours and minutes since
activity last occurred on that particular line. A dot
(.) indicates that the terminal has seen activity in
the last minute and is therefore ``current''. If more
than twenty-four hours have elapsed or the line has
not been used since boot time, the entry is marked
old. This field is useful when trying to determine
whether a person is working at the terminal or not.
The pid is the process ID of the user's shell. The
comment is the comment field. It can contain
information about where the terminal is located, the
telephone number of the dataset, the type of terminal
if hard-wired, etc.
-A This option displays UNIX accounting information.
-T This option is the same as the -u option, except that
the state of the terminal line is printed. The state
describes whether someone else can write to that
terminal. A plus character (+) appears if the
terminal is writable by anyone; a minus character (-)
appears if it is not. Root can write to all lines
having a plus character (+) or a minus character (-)
in the state field. If a bad line is encountered, a
question mark (?) is displayed.
-l This option lists only those lines on which the system
is waiting for someone to login. The name field is
LOGIN in such cases. Other fields are the same as for
user entries except that the state field does not
exist.
-H This option displays column headings above the regular
output.
-q This is a quick who, displaying only the names and the
number of users currently logged on. When this option
is used, all other options are ignored.
-d This option displays all processes that have expired
and have not been respawned by init. The exit field
appears for dead processes and contains the
termination and exit values (as returned by wait(S)),
of the dead process. This can be useful in
determining why a process terminated.
-t This option indicates the last change to the system
clock (via the date(C) command) by root. See su(C).
-a This option processes the /etc/utmp file or the named
file with all options turned on.
-s This option is the default and lists only the name,
line, and time fields.
-p This option lists any other process which is currently
active and has been previously spawned by init. The
name field is the name of the program executed by init
as found in /tcb/files/inittab. The state, line, and
idle fields have no meaning. The comment field shows
the id field of the line from /tcb/files/inittab that
spawned this process. See inittab(F).
-b This option indicates the time and date of the last
reboot.
-r This option indicates the current run-level of the
init process. In addition, it produces the process
termination status, process id, and process exit
status [see utmp(F)] under the idle, pid, and comment
headings, respectively.
Files
/etc/utmp
/etc/wtmp
/tcb/files/inittab
See Also
date(C), login(M), mesg(C), su(C), utmp(F), inittab(F),
wait(S)
Standards Conformance
who is conformant with:
AT&T SVID Issue 2, Select Code 307-127;
and The X/Open Portability Guide II of January 1987.
(printed 8/24/89) WHO(C)