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who(1)
NAME
who - Identifies users currently logged in
SYNOPSIS
who [-a] | [-AbdhHlmMpqrstTu] [file]
who am I
who am i
whoami
The who command displays information about users and processes on the local
system.
STANDARDS
Interfaces documented on this reference page conform to industry standards
as follows:
who: XCU5.0
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
OPTIONS
-a Specifies all options; processes /var/adm/utmp or the named file with
all options on. Equivalent to using the -b, -d, -l, -p, -r, -t, -T, and
-u options.
-A [Tru64 UNIX] Displays accounting entries from the specified file.
Accounting information is stored in the /var/adm/wtmp file, so you
should specify that file. If you omit the file argument, the who
command attempts to display information from the /var/adm/utmp file,
which normally contains no accounting information. If accounting has
never been enabled on your system, this option causes the who command
to produce no output.
-b Indicates the most recent system start-up time and date.
-d Displays all processes that have expired without being regenerated by
init. The exit_status field appears for dead processes and contains
the termination and exit values (as returned by wait) of the dead
processes. (This option is useful for determining why a process
ended.)
-h [Tru64 UNIX] Displays a help message.
-H Displays a header (title).
-l Lists only terminals not in use. The user field is LOGIN in such cases.
Other fields are the same as for user entries except that the state
field does not appear.
-m Displays information about the current terminal (same as who am i or
who am I).
-M [Tru64 UNIX] Lists only the user, line, time and host (if not null)
fields.
-p Lists any active process that is currently active and was previously
generated by init.
-q Prints a quick listing of users and the number of users on the local
system. When you use this option, all other options are ignored.
-r Indicates the current run-level of the system and provides information
about the system's state. An example might be:
. run-level 3 Jan 02 07:34 3 0 S
. is a placeholder for the user name field.
Jan 02 07:34 is when the current run-level was last entered.
The 3 is the current state or run level (termination status).
The 0 is the number of times the current state has been entered
previously (id).
The S is an identification of the previous state or run level (exit
status).
-s Lists only the user, line and the time fields. (This is the default;
thus, who and who -s are equivalent).
-t Indicates the last change to the system clock by the superuser using
the date command.
-T Displays the status of the terminal line and indicates who can write to
that terminal as follows:
+ Writable by anyone.
- Writable only by the superuser or the terminal's owner.
? [Tru64 UNIX] Bad line encountered.
-u Displays the username, terminal name, login time, line activity and the
process-ID of each current user.
OPERANDS
file
Name of the file to be used, instead of /var/adm/utmp, to obtain the
information.
DESCRIPTION
The who command displays the following information for the users and/or
processes you specify:
· Login name
· Terminal name
· Date
· Time of login
· Host
Entering who am i or who am I displays your login name, terminal name, date
and time you logged in and the host. This is equivalent to the -m option.
[Tru64 UNIX] Entering whoami displays your login name only.
With options, who also can display the elapsed time since line activity
occurred, the process-ID of the command interpreter (shell), logins,
logouts, restarts and changes to the system clock, as well as other
processes generated by the init process.
The general output format of the who command is as follows:
user [state] line time activity process_ID [exit_status]
· user is the user's login name.
· state indicates whether or not the line is readable by everyone (see
the -T option).
· line is the name of the line as found in the /dev directory.
· time is the time that user logged in.
· activity is the hours and minutes since activity last occurred on that
user's line. A . (dot) here indicates line activity within the last
minute. If the line has been quiet more than 24 hours or has not been
used since the last system start-up, the entry is marked as old.
· process_ID is the process-ID of the user's shell.
· exit_status is the exit status of ended processes (see the -d option).
[Tru64 UNIX] To obtain its information, who normally examines
/var/adm/utmp. If you specify another file, who examines the named file
instead. This file will usually be /var/adm/wtmp, which contains the
history of all logins since the file was last created.
Note that who only identifies users on the local node.
EXAMPLES
1. To display information about who is using the local system, enter:
who
Information similar to the following is displayed:
george console Jun 8 08:34
2. To display your username, enter:
whoami
Information similar to the following is displayed:
huang
3. To display a history of logins, logouts, system start-ups and system
shutdowns, enter:
who /var/adm/wtmp
Information similar to the following is displayed:
huang console Jun 8 08:34
john console Jun 8 08:34
rachel console Jun 8 08:22
spike ttyp4 Jun 8 09:19
4. To display the run-level of the local system, enter:
who -r
Information similar to the following is displayed:
run-level 3 Jan 05 08:36 3 0 S
5. To display any active process that is currently active and was
previously generated by init, enter:
who -p
Information similar to the following is displayed:
. tty4 Jun 8 04:15
. tty7 Jun 8 04:15
. tty14 Jun 8 04:15
EXIT STATUS
The following exit values are returned:
0 Successful completion.
>0 An error occurred.
ENVIRONMENT VARIABLES
The following environment variables affect the execution of who:
LANG
Provides a default value for the internationalization variables that
are unset or null. If LANG is unset or null, the corresponding value
from the default locale is used. If any of the internationalization
variables contain an invalid setting, the utility behaves as if none of
the variables had been defined.
LC_ALL
If set to a non-empty string value, overrides the values of all the
other internationalization variables.
LC_CTYPE
Determines the locale for the interpretation of sequences of bytes of
text data as characters (for example, single-byte as opposed to
multibyte characters in arguments).
LC_MESSAGES
Determines the locale for the format and contents of diagnostic
messages written to standard error.
LC_TIME
Determines the locale used for the format and contents of date and time
strings in the output.
NLSPATH
Determines the location of message catalogues for the processing of
LC_MESSAGES.
FILES
/var/adm/utmp
Contains user and accounting information.
/var/adm/wtmp
Contains login history.
SEE ALSO
Commands: date(1), init(8), login(1), mesg(1), su(1), rwho(1), users(1),
wait(1), whoami(1)
Functions: wait(2)
Files: utmp(4)
Standards: standards(5)
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