who - show who is logged on

To print who command output without options

$ who

To print the heading of the columns displayed

$ who -H

To print the login names and total number of logged on users

$ who -q

To show only hostname and user associated with stdin

$ who -m

To add user's message status as +, - or ?

$ who -T

To view the time of last system boot

$ who -b

To check the current runlevel

$ who -r

To print dead processes
$ who -d

To see active processes spawned by init

$ who -p

To print last system clock change

$ who -t

To list users logged in

$ who -u

To print same as -b -d --login -p -r -t -T -u

$ who -a

regards,

T.Dhanasekar