I Use a lot linux in my job so i will post here all the command i use a lot or discoverd during my daily use.

Search in history

In my day i usuly use the same command again and again exemple i regulary connect with ssh to the test server to check that everything is correct. I discovert that commad
ctrl + R
that can search for you in your history

Replay a command

This arrive everyday to me you have to excute a commande in sudo but you forget to tape sudo before the command instead of retape all the command you can juste use :
sudo !!

!! will repeat the last command you tape.

Search the biggest file.

Some time i have to check what file or directory is taking all the place on my system. For this i use

du -hms * | sort -nr | head