Starting from this question, I realized that the proper usage of bash commands to handle FASTA files* could be, for those (like me) not proficient with the usage of the terminal, a difficult task. Also, I feel it is important to learn how to use them correctly. Could you point me out what are, in your personal experience, the most important commands useful in FASTA lists manipulation? Possibly, I would prioritize commands wich are easy to use and, possibly, versatile.
If you want, I agree to treat the topic as a community wiki.
*Extract IDs, remove certain sequences, edit descriptions, listing only the sequences that start with A and similar.