Beets

Beets is the best command-line tool for viewing, querying, and renaming your music collection.

Because beets is designed as a library, it can do almost anything you can imagine for your music collection. Via plugins, beets becomes a panacea:

• Fetch or calculate all the metadata you could possibly need: album art, lyrics, genres, tempos, ReplayGain levels, or acoustic fingerprints.
• Get metadata from MusicBrainz, Discogs, or Beatport. Or guess metadata using songs’ filenames or their acoustic fingerprints.
• Transcode audio to any format you like.
• Check your library for duplicate tracks and albums or for albums that are missing tracks.