who(1) who(1)
NAME
who - show who is on the system
SYNOPSIS
who [option ...] [file] Format 1
who -q [-n number] [--] [file] Format 2
who am i Format 3
who am I Format 4
DESCRIPTION
who provides information on:
- the login and terminal name under which you are currently working
- the login name, login time, and terminal name for each current sys-
tem user
- the process ID of the command interpreter (shell) being used
- the last time a terminal was used
- when logins, logouts, and system breakdowns have taken place since
the /var/adm/wtmp file was cleared by the system administrator.
- the last time the system clock was changed
- the processes spawned by the init process
Note:
who normally gets its information from the/var/adm/utmp file. The
information in this file is brought up to date every time a login
is performed. In single-user mode no logins are performed. Thus
after a shutdown to single-user mode who may not be able to supply
accurate information about the current login status. Use who am i
instead.
To obtain the same information if the /var directory (or the direc-
tory corresponding to it in your system configuration) is not
mounted in the file system in single-user mode, you should proceed
as follows: Call the who command giving the temporary files
tmputmp and tmpwtmp as arguments. These files reside in the
/stand directory.
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OPTIONS
Format 1: List detailed information
who [option ...] [file]
No option specified:
who lists the following for every system user currently logged
in:
- login name under which the user logged in
- name of the terminal on which the user logged in
- login time.
The columns in the output are described below in Output.
-a (a - all) Turns on options -b, -d, -l, -p, -r, -t, -T and -u.
-b (b - boot) Shows the date and time of the last reboot.
-d (d - dead) Shows all processes that have terminated and not been
respawned by init. Produces a list of dead processes together
with their exit status and the number of the signal which ter-
minated the process. This may be useful in determining why a pro-
cess died.
-H (H - headings) Prints headings above the output columns.
-l (l - login) Lists the processes where the system is waiting for
someone to log in. In such cases the entry in the NAME field is
the name of the program (or LOGIN). The other fields have their
usual meanings.
-m who only outputs information on the active terminal.
-p (p - process) Shows all processes spawned by the init process.
The NAME field shows the name of the program executed by init as
listed in /etc/inittab [see inittab(4)].
The LINE field is irrelevant in conjunction with the -p option,
so only a dot is output in this field. The COMMENTS field is not
displayed unless you combine -p with -a or with -l and/or -u. In
these cases the comment field contains the entry from the corre-
sponding line in /etc/inittab [see inittab(4)].
-r (r -run level) Shows the current run level of the init process.
The LINE field indicates the current run level, the TIME field
the date it was entered.
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who(1) who(1)
IDLE shows the current run level in numeric form, PID shows how
often the system has been in this state before, and COMMENTS
indicates the system's previous run level. The NAME field has no
meaning with the -r option.
-s (s - standard) Lists the users who are currently logged in. The
NAME field gives the login name, LINE is the device name (without
the /dev/) of the terminal on which the user logged in. TIME
shows when the user logged in.
This option is the default. -s cannot be combined with -a, -d, or
-T.
-T (T - terminal) The terminal state is output in addition to the
default values. The LINE field shows whether other users can
write to the terminal: a plus sign + indicates that they can, a
minus sign - means that they cannot. The system administrator can
write to any terminal. If it is not possible for the system to
obtain this information, a question mark ? appears in this field.
-t (t - time) Shows the last time the system administrator changed
the system clock (using the date command).
-u (u - user) Lists those users who are currently logged in. The
NAME field is the user's login name. LINE is the device name
(without the /dev/) of the terminal on which the user logged in.
TIME shows when the user logged in.
The IDLE field provides information on the last time there was
activity on the terminal in question: a dot (.) indicates
activity within the last minute. If the terminal has not been
used for over 24 hours or since the system was last booted, the
entry is marked old.
The PID field indicates the process ID of the command interpreter
(shell) the user is working with. COMMENTS is a comment about the
terminal as contained in /etc/inittab [see inittab(4)]. This com-
ment may provide information about where the terminal is located
and similar topics.
-- If file begins with a dash (-), the end of the command-line
options must be marked with --.
file Name of the file from which who obtains its information. file, if
given, will typically be /var/adm/wtmp. who then provides infor-
mation about logins, logouts and system breakdowns that have
taken place since this file was last cleared by the system
administrator.
file not specified:
who obtains its information from the file /var/adm/utmp.
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Output
The following section lists the headings of the columns output by who
and discusses the information displayed in each column.
The output columns have different meanings in some cases with the -b,
-d, -p, -r, and -t options.
NAME Indicates the user's login name.
LINE Gives the device name (without the /dev/) of the terminal on
which the user logged in.
TIME Shows when the user logged in.
IDLE Provides information on the last time there was activity on the
terminal in question: a dot (.) indicates activity within the
last minute. If the terminal has not been used for over 24 hours
or since the system was last booted, the entry is marked old.
PID Indicates the process ID of the command interpreter (shell) the
user is working with.
COMMENTS
Contains a comment about the terminal as contained in
/etc/inittab [see inittab(4)]. This comment may provide informa-
tion about where the terminal is located and similar topics.
Format 2: List concise information
who -q [-n number] [--] [file]
-q (q - quick) who only outputs the names and number of users
currently logged on. Additional options, with the exception of
-n, are ignored.
-n number
who displays number users per line. number must be at least 1.
-- If file begins with a dash (-), the end of the command-line
options must be marked with --.
file See Format 1.
Format 3, Format 4: List information on the invoking user
who am i
who am I
Identical to who -m. who lists:
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- the login name under which you logged in
- the device name (without the /dev/) of the terminal on which you
logged in
- the login time.
LOCALE
The LCMESSAGES environment variable governs the language in which
message texts are displayed.
The LCTIME environment variable governs the format of date and time
strings.
If LCMESSAGES or LCTIME is undefined or is defined as the null
string, it defaults to the value of LANG. If LANG is likewise unde-
fined or null, the system acts as if it were not internationalized.
The LCALL environment variable governs the entire locale. LCALL
takes precedence over all the other environment variables which affect
internationalization.
If any of the locale variables has an invalid value, the system acts
as if none of the variables were set.
EXAMPLES
Example 1
Listing general information on all users currently logged in by cal-
ling who without options.
$ who
martin tty001 Mar 7 10:53
moira tty002 Mar 7 11:10
Example 2
Listing detailed information with column headings on all users
currently logged in by calling who with the -H and -u options.
$ who -Hu
NAME LINE TIME IDLE PID COMMENTS
martin tty001 Mar 7 10:53 . 6252
moira tty002 Mar 7 11:10 0:22 6289
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Example 3
Listing concise information on all users currently logged in by cal-
ling who with the -q option.
$ who -q
martin moira
# users=2
Example 4
Listing information on the invoking user with who am i.
$ who am i
martin tty001 Mar 7 10:53
FILES
/var/adm/utmp
File from which who obtains its information by default. This file
records the latest status.
/var/adm/wtmp
This file can be used as an alternative to /var/adm/utmp. This
file is regularly cleared by the system administrator.
/etc/inittab
Configuration file for the init system process.
SEE ALSO
date(1), login(1), mesg(1), su(1), whoami(1), init(1M), wait(2),
inittab(4), utmp(4).
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