Add cover image to audio file with ffmpeg
Credit to baeldung/linux
Pretty simple command but it took me a while to find it.
INFO
The below command works for mp3, m4a, mp4, ogg, wma
ffmpeg -i song.mp3 -i image.jpg -map_metadata 0 -map 0 -map 1 -acodec copy song_with_cover.mp3
For .flac
audio files use the below command
ffmpeg -i song.flac -i image.jpg -map_metadata 0 -map 0 -map 1 -acodec copy -disposition:v attached_pic song_with_cover.flac