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.

The exiftool command can be used to read or write metadata for different file formats from the command line, which can be especially useful when you need to process automated files in larger quantities. In this description, we will review some of the more general usage examples, as well as test a complete automation shell script that copies IPTC data from JPG files to EPS files.

Unfortunately, the more common compression programs work on only one thread, so they can't take advantage of today's modern, multi-core processors. In this description, we will learn about the pigz program, which can be used to run the compression process on multiple threads, thereby taking advantage of all the processor cores.