I want to use a command line, but don't know how this configuration looks like and where to save it.
According to the source code, it uses GConf to store configuration. Gconf can be manipulated from the command line using gconftool-2 but you do need to understand the schema because
gconftool is pretty low-level and can't ensure that your changes are correct or consistent.
You might find it easier to use the nautilus action configuration tool to change an action and
gconftool to see what gets changed than to make sense of the schema description directly.
When they are exported by going to
tools: export aassistant (also, look at
Edit-Preferences-Export) they contain Gconf settings, but at the same time the settings made in nautilus action configuration tool are
.desktop files created in
/.local/share/file-manager/actions, and those do not contain such settings, except some that stand for the upper levels of a tree-menu.
For example, after creating this setting in Nautilus action configuration tool:
which gives this:
the upper level menus like "Subtitles" and "Download subtitles" contain lines like
ItemsList=3f0b618c-c6fe-436c-86a9-2ebd9b1a77dd;1601ae38-5d78-4214-aeef-b7feb9864fc7;d67b7f55-6b10-418b-bfe8-eb9d4e5e7732;66242038-c8b1-414f-9ef2-4d5bb831a027;, which are gconf settings that cannot really be edited manually in the text file, while the lowest level items (the actions themselves - EN, RO, FR, etc) do not have such code lines and can be edited.