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(5) 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]
where:
name
User's login name
state
Capability of writing to the terminal
line
Name of the line found in /dev
time
Time since user's login
idle
Time elapsed since the user's last activity
pid
User's process id
comment
exit
Exit status for dead processes
The following options are supported:
-a
Processes /var/adm/utmpx or the named file
with -b, -d, -l, -p, -r, -t,
-T, and -u options turned on.
-b
Indicates the time and date of the last reboot.
-d
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.
-H
Outputs column headings above the regular output.
-l
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.
-m
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.
-p
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
/etc/inittab. The
state,
line, and
idle fields have no meaning. The
comment field shows the
id field of the line from
/etc/inittab that spawned this process. See
inittab(5).
-q
(Quick who) Displays only the names and the number
of users currently logged on. When this option is used, all other options are
ignored.
-r
Indicates the current run-level of the init
process.
-s
(Default) Lists only the name, line, and
time fields.
-T
Same as the
-s option, except that the
state idle,
pid, and
comment, fields are also
written.
state is one of the following characters:
+
The terminal allows write access to other users.
−
The terminal denies write access to other users.
?
The terminal write-access state cannot be
determined.
-T
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.
-t
Indicates the last change to the system clock (using the
date utility) by
root. See
su(8) and
date(1).
-u
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
/etc/inittab (see
inittab(5)). 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.
file
Specifies a path name of a file to substitute for the
database of logged-on users that who uses by default.
See environ(7) for descriptions of the following
environment variables that affect the execution of who: LANG,
LC_ALL, LC_CTYPE, LC_MESSAGES, LC_TIME, and
NLSPATH.
The following exit values are returned:
0
Successful completion.
>0
An error occurred.
/etc/inittab
Script for init
/var/adm/utmpx
Current user and accounting information
/var/adm/wtmpx
Historic user and accounting information
See attributes(7) for descriptions of the following
attributes:
| ATTRIBUTE
TYPE |
ATTRIBUTE VALUE |
| Interface Stability |
Standard |
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.