In unix system to view real-time system process activity you can use

top

And some usefull hot keys

t     Displays summary information off and on.
m     Displays memory information off and on.
A     Sorts the display by top consumers of various system resources. Useful for quick identification of performance-hungry tasks on a system.
f     Enters an interactive configuration screen for top. Helpful for setting up top for a specific task.
o     Enables you to interactively select the ordering within top.
r     Issues renice command.
k     Issues kill command.
z     Turn on or off color/mono