who
PURPOSE
Identifies the users currently logged in.
SYNOPSIS
who [-uTldbtas] [ file ]
who am i
DESCRIPTION
The who command with no flags writes to standard output
the login name, work station name, and date and time of
login for all users currently on the system. who am i
gives this information only for you.
With flags, who can also 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 format of the output of who is as follows:
name [state] line time activity pid [location] [exit]
where:
o "name" is the user's login name.
o "state" indicates whether or not the line is readable
by everyone (see the -T flag).
o "line" is the name of the line as found in the direc-
tory /dev.
o "time" is the time that user logged in.
o "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 startup, the entry is
marked old.
o "pid" is the process-ID of the user's shell.
o "location" is the location associated with this line
as found in file /etc/ports. This file can contain
information about where the work station is located,
the telephone number of the dataset, the type of work
station if direct-connected, and other related infor-
mation.
o "exit" is the exit status of ended processes (see the
-d flag).
To obtain its information, who normally examines
/etc/utmp. If you specify another file, who examines the
named file instead. This file will usually be
/usr/adm/wtmp, which contains the history of all logins
since the file was last created or /etc/.ilog, which con-
tains the history of invalid logins. Only someone oper-
ating with superuser authority or a member of the system
group can examine /etc/.ilog
Note: This command only identifies users on the local
node.
FLAGS
-a Processes /etc/utmp or the named file with all flags
on.
-b Indicates the time and date of the most recent
system startup. The NLTIME and NLLDATE environment
variables control the format of the login time and
date.
-d Displays all processes that have expired without
being regenerated by init. The exit field appears
for dead processes and contains the termination and
exit values (as returned by wait) of the dead
process. (This flag is useful for determining why a
process ended.)
-l Lists only work stations not in use. The name field
is LOGIN in such cases. Other fields are the same
as for user entries except that the state field
doesn't appear.
-p Lists any active process that is currently active
and has been previously generated by init.
-r Indicates the current run-level of the process.
-s Lists only the name, line, and time fields. (This
is the default; thus, who and who -s are equiv-
alent.) The NLTIME environment variable controls
the format of the time.
-t Indicates the last change to the system clock by the
superuser using the date command. The NLTIME envi-
ronment variable controls the format of the time.
-T Displays the state of the work station line and
indicates who can write to that work station as
follows:
+ writable by anyone
- writable only by the superuser or its owner
? bad line encountered.
-u Displays the user name, work station name, login
time, line activity, and process-ID of each current
user. The NLTIME environment variable controls the
format of the login time.
EXAMPLES
1. To display information about who is using the system:
who
This lists the user name, work station name, and
login time of all users currently using the system.
2. To display your user name:
who am i
This displays the user name you typed when you logged
in, the name of the work station you are using, and
the time you logged in. Your login user name may be
different from your current user name if you have
used the su command.
3. To display a history of logins, logouts, system
startups, and system shutdowns:
who /usr/adm/wtmp
FILES
/etc/utmp
/usr/adm/wtmp
/etc/ports
RELATED INFORMATION
The following commands: "date," "init," "login,"
"mesg," and "su."
The wait system call and the ports and utmp files in AIX
Operating System Technical Reference.
"Overview of International Character Support" in Managing
the AIX Operating System.