APT package manager is a built-in command-line tool for Debian-based distributions like Ubuntu to mange your applications in your Linux system.

DNF is the default package manager for RHEL-based distributions like Fedora and AlmaLinux to help you manage your system packages.

You are Arch based users, so I expect that you already know about the Pacman package manager; if not, it’s just a built-in command line tool to manage your system packages.

The grep command is used to perform regular expressions to find out strings and patterns from the file that match a regular expression.