Accurate calculation of CPU usage given in percentage in Linux?

Question

It\'s a question which has been asked many times, however there is no well supported answer I could find.

Many people suggest the use of top command, but if you run

Answer 1

idnt.net has a good description for how to use the /proc/stat cpu data, include a bash-script for extracting cpu and description of the lines. I just wanted to link it here, since I found it valuable.