This would be the data export pair to the existing "--set-tag-from-file=FIELD=filename" option.
As it stands, there is no easy way to extract comment content when the field contains multi-line data.
E.g. using:
metaflac --show-tag=CUESHEET "flacfile.flac" >"cuesheet.cue"
..yields the correct data, but includes the "CUESHEET=" header in the file...which is undesirable.
Josh Coalson
2009-01-02