WARNING backup your Darktable database before any actions, usually it located in ~/.config/darktable/*.db
Also be careful with rm command, it is better also to backup all files
Delete, rename, create tags
dtag list used tags
dtag -d 'wood' delete tag wood
dtag -r 'old name' -n 'new name' rename tag
Cleanup database
dt_db --help
Dump metada to stdout in JSON format
dt_dump
Restore meta from stdin, there is a lot of command line flags
dt_restore --help
Restore dump, enable tag add and delete, ignote tag 'winter', dry mode
cat dump.json | ./dt_restore --at --dt -i winter -n
Find non imported files in roll directories
dt_files --nf
Find orphaned xmp and delete them, use with care (remove echo)
dt_files --ox | xargs -0 echo rm -v
Find updated xmp files and run darktable to re-import them
darktable $(./dt_files --ui)
Helpers to send and receive export/import files
meta_get
meta_send
Config files for helpers
meta.conf
meta.conf.example