Which command checks for available updates in an Ubuntu system?

The command that checks for available updates in an Ubuntu system is specifically designed to update the package index, which contains information about the most recent versions of packages and their dependencies. The command ‘apt update’ connects to the appropriate repositories configured in the system and retrieves the latest information, allowing the user to see which packages have updates available.

Using ‘apt upgrade’ would not check for updates; instead, it would apply any updates that are already known to the system based on the information retrieved from previous invocations of ‘apt update’. The command ‘apt install’ is used for installing new packages rather than checking for updates, while ‘apt remove’ is used to uninstall packages from the system. Thus, ‘apt update’ is essential for obtaining information on available updates before proceeding with any installations or upgrades.