who command

NAME

       who - show who is logged on

SYNOPSIS

       who [OPTION]... [ FILE | ARG1 ARG2 ]

DESCRIPTION

       Print information about users who are currently logged in.

       -a, --all                             same as -b -d --login -p -r -t -T -u

       -b, --boot                                      time of last system boot

       -d, --dead                                     print dead processes

       -H, --heading                    print line of column headings

       -l, --login                                      print system login processes

       --lookup                            attempt to canonicalize hostnames via DNS

       -m                                     only hostname and user associated with stdin

       -p, --process                     print active processes spawned by init

       -q, --count                        all login names and number of users logged on

       -r, --runlevel                     print current runlevel

       -s, --short                          print only name, line, and time (default)

       -t, --time                                       print last system clock change

   -T, -w, --mesg                                   add user’s message status as +, - or ?

       -u, --users                                     list users logged in

       --message                        same as -T

       --writable                         same as -T

       --help                                display this help and exit

       --version                                       output version information and exit

If FILE is not specified, use /var/run/utmp.  /var/log/wtmp as FILE is common.  If ARG1 ARG2 given, -m presumed: ‘am i’ or ‘mom likes’ are usual.