It could be useful to merge a number of mp3 files into one using the following command:
ffmpeg -i "concat:file1.mp3|file2.mp3|file3.mp3|file4.mp3|file5.mp3|file6.mp3|file7.mp3|file8.mp3" -acodec copy _all_files_combined.mp3
The command above will combine mp3 files listed in -i option into one large audio file called _all_files_combined.mp3.
Check out video tutorial version located on my Youtube channel Linux Tutorials at: https://youtu.be/1YM_G7nPQo4