What command is used to update package information in Debian-based systems?

The command used to update package information in Debian-based systems is indeed apt update. This command is essential in the apt package management system, which is widely used in distributions such as Ubuntu and Debian.

When you run apt update, the system retrieves the latest information about available packages and their versions from the repositories configured on your system. This ensures that when you later decide to install or upgrade packages, you are using the most current versions available. Regularly updating package information is a crucial part of system maintenance, as it allows users to receive the latest security updates and features.

In contrast, other commands mentioned serve different purposes. For instance, apt upgrade is used after running apt update; it actually performs the process of upgrading installed packages to their latest versions based on the updated information. apt install is utilized to install new packages, while apt remove is used to uninstall existing packages. Each command performs a specific function within package management, highlighting the importance of apt update as a prerequisite to ensure the effectiveness of subsequent actions.