sudo apt update is a necessary prerequisite step before running sudo apt full-upgrade
If you run sudo apt full-upgrade without having previously run sudo apt update, the full-upgrade command will not install the updated packages.
The sudo apt full-upgrade command uses the list of packages in the APT cache, which is updated when sudo apt update is run. If sudo apt update has not been run recently, the list of packages in the APT cache may be out of date, meaning that no updated packages are known to be available.
sudo apt update- It does not install or update packages, it only updates the list of available packages.
- This is a read-only command, it does not modify the system.
- Used to get the latest list of available packages before installing or updating packages.
sudo apt full-upgrade- Install new packages that are required for the upgrade.
- Remove packages that are no longer needed or are obsolete.
- It is a command that modifies the system, since it installs, updates or removes packages.
- It is used to keep the system up to date and secure by installing the latest security and feature updates.
When you run sudo apt full-upgrade without having previously run sudo apt update, the command will perform the following actions:
- It will check the list of packages installed on the system.
- It will check the list of packages in the APT cache (which may be out of date).
- It will not find any updated packages available, since the list of packages in the APT cache has not been updated.
- It will not install anything, since there are no known updated packages available.
It is recommended to always run sudo apt update before running sudo apt full-upgrade. This ensures that the package list in the APT cache is up to date and any available updated packages can be installed.