NAME

who - Identifies users currently logged in

SYNOPSIS

who [-a] | [-AbdHlmMpqrstTu?hM] [file]

who am I | who am i | whoami

The who command displays information about users and processes on the local system. 

FLAGS

?hPrints a help message

-aSpecifies all options; processes /var/adm/utmp or the named file with all flags on

-AfileDisplays 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. 

-bIndicates the most recent system start-up time and date.  The LC_TIME environment variable controls the format of the login time and date. 

-dDisplays 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 flag is useful for determining why a process ended.) 

-hDisplays a help message. 

-HDisplays a header (title). 

-lLists only ttys 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. 

-mDisplays information about the current tty (same as who am i). 

-MLists only the user, line, time, and host (if not null) fields. 

-pLists any active process that is currently active and was previously generated by init. 

-qPrints a quick listing of users and the number of users on the local system. When you use this option, all other options are ignored. 

-rIndicates 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

The date and time of the last state change. 

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). 

-sLists only the user, line, and time fields.  (This is the default; thus, who and who -s are equivalent.)  The LC_TIME environment variable controls the format of the time. 

-tIndicates the last change to the system clock by the superuser using the date command.  The LC_TIME environment variable controls the format of the time. 

-TDisplays the status of the tty line and indicates who can write to that tty as follows:

+Writable by anyone. 

-Writable only by the superuser or the tty’s owner. 

?Bad line encountered. 

-uDisplays the username, terminal name, login time, line activity, and process-ID of each current user.  The LC_TIME environment variable controls the format of the login time. 

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 host. Entering whoami displays your login name only. 

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 output format of the who command is as follows:

user [state] line time activity process_ID [exit_status]

where:

       •user is the user’s login name. 

       •state indicates whether or not the line is readable by everyone (see the -T flag). 

       •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 flag). 

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  (abcpa.pasc.abc.c)

     2.To display your username, enter:

who am i

Information similar to the following is displayed:

huangconsole Jun 808:34  (maguro)

     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:

huangconsoleJun 808:34
johnconsoleJun 808:34
rachelconsoleJun 808:22
spikettyp4Jun 809:19

     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:

.tty4Jun 804:15
.tty7Jun 804:15
.tty14Jun 804:15

FILES

/var/adm/utmpContains user and accounting information. 

/var/adm/wtmpContains login history. 

RELATED INFORMATION

Commands:  date(1), init(8), login(1), mesg(1), su(1), users(1) whoami(1). 

Functions:  wait(2). 

Files:  utmp(4).