How do I share my database between 2 computers on the same network. One is Windows 10, the other is Ubuntu 20.04. My database resides in the Windows partition but was built using Ubuntu. When I supply the correct path to my Windows version I don't know how to make it use that DB. I've tried New DB but cannot make it point to the existing DB. It wants to create a brand new one.
There are two ways.
The simpler way is to create a new, empty tree then import your existing database into it.
You should then be able to save the tree and convince Gramps to use the existing file location.
Or, more tricky, you can do this from the command line.
In Windows, instead of opening Gramps in the normal way, open the console mode.
Issue an open command
python gramps.py -O /your-path-to-gramps/.gramps/grampsdb/47320f3d
Note that you need the 8-character hexadecimal database identity, not the name of the tree.
Once opened in this manner, the tree becomes one of your "recent trees" and so is easily accessible next time you wish to open it.
This comes from the Gramps user manual here