You saw how to use
ps in Processes for listing process characteristics at any given time.
ps is good for getting a snapshot of the current processes, but it does little to tell you how processes change over time. Using
ps alone, it's not terribly easy to pick out processes that are using too much CPU time or memory.
top program displays the current system status and many of the fields that you might see in a
ps listing, but it also updates the display every second. By default,
top shows the most active processes (that is, those currently taking up the most CPU time).
You can send commands to
top with keystrokes. These are some of the most important commands:
Updates the display immediately
Sorts by current ...