The hostname command is a basic tool in Linux systems that allows you to query or set the computer name. In Linux systems, every machine has a unique name, which we call "hostname". This name allows devices to be identified and accessed within the network. The hostname command can be used to view or change the settings of the current hostname. This command is particularly useful when diagnosing network problems and configuring servers and other network devices.

The md5sum command is a tool that allows you to calculate and check the MD5 (Message Digest Algorithm 5) sum value of files. MD5 is a one-way hash function that produces a fixed-length 128-bit (32 hexadecimal characters) digest from an input string. This hash is often used to verify the integrity of files, since even a small change in the file results in a completely different hash value. In this tutorial, we'll cover the basic usage of the md5sum command on a Debian system.