WHO(1) User Commands WHO(1)


who - who is on the system


/usr/bin/who [-abdHlmpqrstTu] [file]

/usr/bin/who -q [-n x] [file]

/usr/bin/who am i

/usr/bin/who am I

/usr/xpg4/bin/who [-abdHlmpqrtTu] [file]

/usr/xpg4/bin/who -q [-n x] [file]

/usr/xpg4/bin/who -s [-bdHlmpqrtu] [file]

/usr/xpg4/bin/who am i

/usr/xpg4/bin/who am I


The who utility 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/utmpx file to obtain its information. If file is
given, that file (which must be in utmpx(4) format) is examined. Usually,
file will be /var/adm/wtmpx, which contains a history of all the logins
since the file was last created.

The general format for output is:

name [state] line time [idle] [pid] [comment] [exit]


User's login name

Capability of writing to the terminal

Name of the line found in /dev

Time since user's login

Time elapsed since the user's last activity

User's process id

Comment line in inittab(4)

Exit status for dead processes


The following options are supported:

Processes /var/adm/utmpx or the named file with -b, -d, -l, -p,
-r, -t, -T, and -u options turned on.

Indicates the time and date of the last reboot.

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 of the dead process. This can be
useful in determining why a process terminated.

Outputs column headings above the regular output.

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.

Outputs only information about the current terminal.

-n x
Takes a numeric argument, x, which specifies the number of users
to display per line. x must be at least 1. The -n option can
only be used with -q.

Lists any other process that 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).

(Quick who) Displays only the names and the number of users
currently logged on. When this option is used, all other options
are ignored.

Indicates the current run-level of the init process.

(Default) Lists only the name, line, and time fields.

Same as the -s option, except that the state idle, pid, and
comment, fields are also written. state is one of the following

The terminal allows write access to other users.

The terminal denies write access to other users.

The terminal write-access state cannot be determined.

Same as the -s option, except that the state field is also
written. state is one of the characters listed under the
/usr/bin/who version of this option. If the -u option is used with
-T, the idle time is added to the end of the previous format.

Indicates the last change to the system clock (using the date
utility) by root. See su(1M) and date(1).

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 contain information about where the terminal
is located, the telephone number of the dataset, type of terminal
if hard-wired, and so forth.


The following operands are supported:

am i
am I
In the "C" locale, limits the output to describing the invoking
user, equivalent to the -m option. The am and i or I must be
separate arguments.

Specifies a path name of a file to substitute for the database
of logged-on users that who uses by default.


See environ(5) for descriptions of the following environment variables
that affect the execution of who: LANG, LC_ALL, LC_CTYPE, LC_MESSAGES,


The following exit values are returned:

Successful completion.

An error occurred.


Script for init

Current user and accounting information

Historic user and accounting information


See attributes(5) for descriptions of the following attributes:


|Interface Stability | Standard |


date(1), login(1), mesg(1), init(1M), su(1M), inittab(4), utmpx(4),
attributes(5), environ(5), standards(5)


Superuser: After a shutdown to the single-user state, who returns a
prompt. Since /var/adm/utmpx is updated at login time and there is no
login in single-user state, who cannot report accurately on this state.
The command, who am i, however, returns the correct information.

May 13, 2017 WHO(1)