The monitoring letter 'w'

In linux you can see who in logged in and which procesws is runnig currently just by typing a letter in terminal

$ w                //this shows who is logged in and what they doing

This prints login name, JCPU, PCPU, idle time, login time, tty, the remote host.

The JCPU time is the time used by all processes attached to the tty. It does not include past background jobs, but does include currently running background jobs. 

The PCPU time is the time used by the current process, named in the "what" field.

COMMAND-LINE OPTIONS

-h

Don't print the header.

-u

Ignores the username while figuring out the current process and cpu times. To demonstrate this, do a "su" and do a "w" and a "w -u".

-s

Use the short format. Don't print the login time, JCPU or PCPU times.

-f

Toggle printing the from (remote hostname) field. The default if for the from field to be printed, although your system administrator or distribution maintainer may have compiled a version in which the from field is not shown by default.

-V

Display version information.

user

Show information about the specified user only.