Yes, most people know of them :-) I just felt like presenting them to people who might not know of them and their strengths. Why not present tools, although many know of them already? I think it is important to talk freely about any software, as there is always someone who might not know them. I appreciate this myself, and i am actually also new with *nix systems. If everyone had the same approach to information as you, i would not be a part of it.
It's probably worth adding to this article as you find new utilities or new ways to use them - look at all the great suggestions in this comment page!
All the suggestions here is amazing. I will take a look at this later. At least make an edit with a list of the suggested software. Did not see this coming :-) Thank you everyone.
I didn't know about apachetop and glances.
I was actually trying to install an app like zabbix before I stumbled on this thread. If these tools can help me monitor the servers, that's even better!
Thanks @adionditsak for sharing.
I for one did not know about glances and apachetop, thanks OP