Name

who - display who is logged in

Synopsis

who [-mTuH] [file]
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:

-m

Only print information about the current terminal. This is the POSIX way of saying who am i.

-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.

-u

Print the idle time for each user.

-H

Write column headings above the regular output.

am I Returns the invoker's real user name.

file By default, who gathers information from the file /var/run/utmp. An alternative file may be specified which is usually /var/log/wtmp (or /var/log/wtmp.[0-6] depending on site policy as wtmp can grow quite large and daily versions may or may not be kept around after compression by ac(8) ). The wtmp file contains a record of every login, logout, crash, shutdown and date change since wtmp was last truncated or created.

If /var/log/wtmp is 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/log/wtmp
/var/log/wtmp.[0-6]

See Also

last(1) , mesg(1) , users(1) , getuid(2) , utmp(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.

Table of Contents

• Name
• Synopsis
• Description
• Files
• See Also
• Standards
• History