Here’s a quick video on finding out what’s going on when you log into (or sit down at) a Linux machine. We cover the following commands:
w (/who): find out who is currently logged into the machine, and where they're connecting from top: find out which processes are running, how much load they're putting on the CPU, and how much memory they're using. (sudo) netstat -tulpn: Check for listening network ports and which processes/programs are using them.
Some Alternatives to the Tools I show in this Video:
I really like a program called htop, which shows you a bit more information and presents it in a nicer format. I recommend using it, once you’re comfortable with top.
htop (sudo apt-get install htop -- quit with 'ctrl-c' or 'q' once it's running)