you have many tools to look at the behavior of your system.
1- The most commonly used is "ps". it has lots of options, and (if not suffcicient ) you can feed its output to "grep" to filter through.
Please refer to the man page of ps and worked out examples for more informations.
2- "top" gives a real time view of your processes (their ID, memory and CPU usage, ...). Again, refer to man pages for all the options.