I'm trying to have everything ready to install a new desktop with a few command line instructions.
Unfortunately, to install the language packages, I couldn't find how to do it.

I can run

gnome-language-selector

But it doesn't seems to be usable in command line directly. I need to go on with clicks...

An other thing that could be done is that I do those clicks and find out which packages have been installed and read the changes in /etc/environment and /etc/default/locale (and other /etc/... file?) but the list of packages is probably different depending on the packages installed (Firefox, Thunderbird, LibreOffice, Gnome, ...)

Is there a tool for that? Like let's say :

gnome-language-selector --install fr

or a package that has all necessary dependencies :

sudo apt-get install super-language-pack-fr

Thanks,