Whowatch is an interactive and easy to use UNIX tool that allows users to monitor in real-time via the Terminal users currently logged on to the machine.
Using a simple text-based user interface, Whowatch can detect both telnet and ssh connections. It also allows to view and browse process tree, send kill signals, etc.
To install Whowatch on Ubuntu (11.10/11.04/10.10/10.04), run this command from the Terminal:
sudo apt-get install whowatch
Start it now with this command: