Which command installs all available updates for packages?

The command that installs all available updates for packages is 'apt upgrade'. This command is part of the Advanced Package Tool (APT) system and is specifically used for upgrading all installed packages to the newest versions available in the repositories. It checks for package updates and installs them, ensuring that the system’s installed software is kept up to date with the latest features and security patches.

While 'apt dist-upgrade' is also a valid command for upgrading packages, it performs more advanced functions than 'apt upgrade'. It not only updates existing packages but also manages dependencies intelligently, which can include installing or removing packages as necessary to complete the upgrade. Therefore, 'apt upgrade' is the more straightforward command for simply installing updates without any additional complexities.

The 'apt install' command is used for installing specific new packages, while 'apt search' is used to search for packages in the available repositories. Neither of these commands will upgrade existing packages, which solidifies 'apt upgrade' as the correct choice for installing all available updates for installed packages.