NAME
who
- display who is logged in
SYNOPSIS
who
[-abdHlmqrstTuv]
[file]
who
am i
DESCRIPTION
The
who
utility displays a list of all users currently logged on, showing for
each user the login name, tty name, the date and time of login, and
hostname if not local.
Available options:
- -a
-
Same as
--bdlprTtuv.
- -b
-
Time of last system boot.
- -d
-
Print dead processes.
- -H
-
Write column headings above the regular output.
- -l
-
Print system login processes.
- -m
-
Only print information about the current terminal.
This is the
POSIX
way of saying
who
am i.
- -p
-
Print active processes spawned by
init(8).
- -q
-
``Quick mode'':
List only the names and the number of users currently logged on.
When this option is used, all other options are ignored.
- -r
-
Print the current runlevel.
Supported runlevels are:
d (
DEATH
)-
The system has halted.
s (
SINGLE_USER
)-
The system is running in single user mode.
r (
RUNCOM
)-
The system is executing
/etc/rc
.
t (
READ_TTYS
)-
The system is processing
/etc/ttys
.
m (
MULTI_USER
)-
The system is running in multi-user mode.
T (
CLEAN_TTYS
)-
The system is in the process of stopping processes
associated with terminal devices.
c (
CATATONIA
)-
The system is in the process of shutting down and will
not create new processes.
- -s
-
List only the name, line and time fields.
This is the default.
- -T
-
Print a character after the user name indicating the state of the
terminal line:
`+'
if the terminal is writable;
`-'
if it is not;
and
`?'
if a bad line is encountered.
- -t
-
Print last system clock change.
- -u
-
Print the idle time for each user, and the associated process ID.
- -v
-
When printing of more information is requested with
-u,
this switch can be used to also printed
process termination signals,
process exit status,
session id for windowing
and the type of the entry, see documentation of ut_type in
getutxent(3).
- am I
-
Returns the invoker's real user name.
- file
-
By default,
who
gathers information from the file
/var/run/utmpx
.
An alternative
file
may be specified which is usually
/var/log/wtmpx
(or
/var/log/wtmp
,
or
/var/log/wtmpx.[0-6]
or
/var/log/wtmp.[0-6]
depending on site policy as
wtmpx
can grow quite large and daily versions may or may not
be kept around after compression by
ac(8)).
The
wtmpx
and
wtmp
file contains a record of every login, logout,
crash, shutdown and date change
since
wtmpx
and
wtmp
were last truncated or
created.
If
/var/log/wtmpx
or
/var/log/wtmp
are being used as the file, the user name may be empty
or one of the special characters '|', '}' and '~'.
Logouts produce an output line without any user name.
For more information on the
special characters, see
utmp(5).
FILES
/var/run/utmp
-
/var/run/utmpx
-
/var/log/wtmp
-
/var/log/wtmp.[0-6]
-
/var/log/wtmpx
-
/var/log/wtmpx.[0-6]
-
SEE ALSO
last(1),
mesg(1),
users(1),
getuid(2),
utmp(5),
utmpx(5)
STANDARDS
The
who
utility is expected to conform to
IEEE Std 1003.2-1992 (``POSIX.2'') .
HISTORY
A
who
utility appeared in
Version 6 AT&T UNIX
.