who(1) (Essential Utilities) who(1)
NAME
who - who is on the system
SYNOPSIS
who [-uTlHqpdbrtas] [ file ]
who -qn x [ file ]
who am i
who am I
DESCRIPTION
who can list the user's name, terminal line, login time, elapsed time
since activity occurred on the line, and the process-ID of the
command interpreter (shell) for each current UNIX system user. It
examines the /var/adm/utmp file to obtain its information. If file
is given, that file (which must be in utmp[4] format) is examined.
Usually, file will be /var/adm/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.
The general format for output is:
name [state] line time [idle] [pid] [comment] [exit]
The name, line, and time information is produced by all options
except -q; the state information is produced only by -T; the idle and
pid information is produced only by -u and -l; and the comment and
exit information is produced only by -a. The information produced
for -p, -d, and -r is explained during the discussion of each option,
below.
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 idle column contains 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 associated with
this line as found in /sbin/inittab [see inittab(4)]. This can
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who(1) (Essential Utilities) who(1)
contain information about where the terminal is located, the
telephone number of the dataset, type of terminal if hard-
wired, etc.
-T This option is the same as the -s option, except that the state
of the terminal line is printed. The state describes whether
someone else can write to that terminal. A + appears if the
terminal is writable by anyone; a - appears if it is not. root
can write to all lines having a + or a - in the state field.
If a bad line is encountered, a ? is printed.
-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 will print 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.
-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 /sbin/inittab.
The state, line, and idle fields have no meaning. The comment
field shows the id field of the line from /sbin/inittab that
spawned this process. See inittab(4).
-d This option displays all processes that have expired and not
been respawned by init. The exit field appears for dead
processes and contains the termination and exit values [as
returned by wait(2)], of the dead process. This can be useful
in determining why a process terminated.
-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(4)] under
the idle, pid, and comment headings, respectively.
-t This option indicates the last change to the system clock (via
the date command) by root. See su(1M).
-a This option processes /var/adm/utmp or the named file with all
options turned on.
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who(1) (Essential Utilities) who(1)
-s This option is the default and lists only the name, line, and
time fields.
-n x This option takes a numeric argument, x, which specifies the
number of users to display per line. x must be at least 1.
The -n option must be used with -q.
Note to the super-user: after a shutdown to the single-user state,
who returns a prompt; the reason is that since /var/adm/utmp is
updated at login time and there is no login in single-user state, who
cannot report accurately on this state. who am i, however, returns
the correct information.
FILES
/var/adm/utmp
/var/adm/wtmp
/sbin/inittab
SEE ALSO
date(1), login(1), mesg(1).
su(1M). init(1M), inittab(4), utmp(4) in the System Administrator's
Reference Manual.
wait(2) in the Programmer's Reference Manual.
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