Update Asterisk

Hello everyone! I still have Asterisk 1.4.21.2 (since we installed it) and I think it’s time to update it also because we should already be at 1.8!
Problem that I don’t know how to update the latest version, only download it, install it and reconfigure everything!
I don’t know how to update from the terminal, if there is any guide, or if you’ve already done! Especially after everything is working!
Thank you!

Did you even try to run a search for this topic on old threads?

This is just one of the numerous hits:

viewtopic.php?f=1&t=79924&p=163561&hilit=upgrade&sid=f79ef978701076fb612d2358a8241aee#p163561