Sometimes, e.g. if you moved your data to an external device which is not permanently available, or even if you just want to use separated databases for managing your photos, it is useful to to start darktable isolated. It is be possible to launch darktable with the --libraryparameter, to force darktable to use a specific database file:
However, with this approach your "default" config files and thumbnail cache is edited as well. For me, that's annoying.
If you start darktable in an isolated home directory, each database comes with its own config files and image cache. Just copy .config/darktableand .cache/darktableto your external device (the library file is located in .config/darktable/library.db):
Take care, to update the path to your photos in library.db(film_rolls is the relevant table). I will write a few sentences about moving darktables photos in another post .
However, /media/EXTERNAL/Photos2011is the isolated home directory and you have kind of this structure:
.cache/ └── darktable ├── mipmaps └── mipmaps.fallback .config └── darktable ├── darktablerc ├── keyboardrc ├── keyboardrc_default └── library.db Photos └── 201112 └── IMG0001.CR3
Remember, the paths to your images has to be updated!
Now you have to set the HOME environment variable to your new directory and start darktable: