Linux Administration Cookbook

How it works...

top queries the kernel to gather information about a running system, making it very fast at reflecting the nature of the box it's been run on. It's also incredibly lightweight, meaning that unless a box is extremely overloaded, there's a good chance top will still run (and if it is overloaded, you've got bigger issues). It's been around since the 1980s; it's tried and tested.

free takes a look at the values available in /proc/meminfo, meaning that while you can query these files yourself (and some people do), free provides a nicer way of looking at values (and gives you the option to refresh on a periodic basis, if that's what you're after).

htop queries the system in much the same way as top (though this isn't necessarily ...