WHO(1) — Silicon Graphics

NAME

who − who is on the system

SYNOPSIS

who [−uTlpdbrtas] [ file ]

who am i

DESCRIPTION

Who can list the user’s name, terminal line, login time, elapsed time since activity occurred on the line, and the process-ID of the command interpreter (shell) for each current UNIX System user. It examines the /etc/utmp file to obtain its information. If file is given, that file is examined. Usually, file will be /etc/wtmp, which contains a history of all the logins since the file was last created.

Who with the am i option identifies the invoking user.

Except for the default −s option, the general format for output entries is:

name [state] line time activity pid [comment] [exit]

With options, who can list logins, logoffs, reboots, and changes to the system clock, as well as other processes spawned by the init process. These options are:

−u This option lists information about those users who are currently logged in. The name is the user’s login name. The line is the name of the line as found in the directory /dev. The time is the time that the user logged in. The activity is the number of hours and minutes since activity last occurred on that particular line. A dot (.) indicates that the terminal has seen activity in the last minute and is therefore "current". If more than twenty-four hours have elapsed or the line has not been used since boot time, the entry is marked old. This field is useful when trying to determine whether a person is working at the terminal or not. The pid is the process-ID of the user’s shell. The comment is the comment field associated with this line as found in /etc/inittab (see inittab(4)). This can contain information about where the terminal is located, the telephone number of the dataset, type of terminal if hard-wired, etc.

−T This option causes the state of the terminal line to be printed. The state describes whether someone else can write to that terminal. A + appears if the terminal is writable by anyone; a − appears if it is not. Root can write to all lines having a + or a − in the state field. If a bad line is encountered, a ? is printed.

−l This option lists only those lines on which the system is waiting for someone to login. The name field is LOGIN in such cases. Other fields are the same as for user entries except that the state field doesn’t exist.

−p This option lists any other process which is currently active and has been previously spawned by init. The name field is the name of the program executed by init as found in /etc/inittab. The state, line, and activity fields have no meaning. The comment field shows the id field of the line from /etc/inittab that spawned this process. See inittab(4).

−d This option displays all processes that have expired and not been respawned by init. The exit field appears for dead processes and contains the termination and exit values (as returned by wait(2)), of the dead process. This can be useful in determining why a process terminated.

−b This option indicates the time and date of the last reboot.

−r This option indicates the current run-level of the init process. Following the run-level and date information are three fields which indicate the current state, the number of times that state was previously entered, and the previous state.

−t This option indicates the last change to the system clock (via the date(1) command) by root. See su(1).

−a This option processes /etc/utmp or the named file with all options turned on.

−s This option is the default and lists only the name, line and time fields.

EXAMPLE

who am i

reports the name under which you are currently logged in. This could be a name other than the original name under which you logged in, if the su command has been used.

FILES

/etc/utmp
/etc/wtmp
/etc/inittab

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