who

Print who is currently logged in

SYNTAX
      who [OPTION] [FILE] [am i]

OPTIONS

`-m'
     Print the current user id, name and domain
     (Same as `who am i')

`-q'
`--count'
     Print only the login names and the number of users logged on.
     Overrides all other options.

`-s'
     Ignored; for compatibility with other versions of `who'.

`-i'
`-u'
`--idle'
     After the login time, print the number of hours and minutes that
     the user has been idle.  `.' means the user was active in last
     minute.  `old' means the user was idle for more than 24 hours.

`-l'
`--lookup'
     Attempt to canonicalize hostnames found in utmp through a DNS
     lookup.  This is not the default because it can cause significant
     delays on systems with automatic dial-up internet access.

`-H'
`--heading'
     Print a line of column headings.

`-w'
`-T'
`--mesg'
`--message'
`--writable'
     After each login name print a character indicating the user's
     message status:

          `+' allowing `write' messages
          `-' disallowing `write' messages
          `?' cannot find terminal device

If given no non-option arguments, `who' prints the following information for each user currently logged on:

login name,
terminal line,
login time,
remote hostname or X display.

If given one non-option argument, `who' uses that instead of `/var/run/utmp' as the name of the file containing the record of users logged on. `/var/run/wtmp' is commonly given as an argument to `who' to look at who has previously logged on.

If given two non-option arguments, `who' prints only the entry for the user running it (determined from its standard input), preceded by the hostname. Traditionally, the two arguments given are `am i', as in `who am i'.

"It is awful work this love and prevents all a mans projects of good or glory" - Lord Byron

Related commands:

groups - Print group names a user is in
hostname - Print or set system name
id - Print user and group id's
uname - Print system information
logname - Print current login name
users - Print login names of users currently logged in
whoami - Print the current user id and name (`id -un')