apt-get

Useful apt / apt-get commands

Full upgrade

 apt update
 apt upgrade
 reboot

Install or upgrade PHP

 apt update
 apt install php7.4

apt-get is the old system

Before doing anything, always update the catalog:

 apt-get update

Tell me what you would upgrade:

 apt-get --simulate upgrade

Install OR upgrade e.g mutt

 apt-get install mutt