Module 1 · The terminal, without fear Lesson 2 of 15

Processes, ports and logs

Worked example

When a site is down the questions are the same every time: is the process running (ps), is anything listening on the port (ss -tulpn), and what does the last hundred lines of the log say (tail -n 100)?

Your practice task

Start a small web server locally, find its process id, find the port it listens on, and kill it — then start it again in the background.

Do this before moving on. Reading a solution teaches the shape of it; typing it teaches you.

Key takeaway

A running program is a process with an id; a service listens on a port; a log is a file that tells you what happened. Those three sentences are most of production troubleshooting.

Almost there

15 lessons left of 15

Finish every lesson to unlock the certificate. Each one ends in a practice task — do them and the final project brief writes itself.