Change language in Firefox and Thunderbird

Just after I installed Debian, I immediately felt the need to install Firefox and Thunderbird, as they are my favorite web and mail browsers.

As they are not present in the debian repositories, I had to use the ones from linuxmint (I added to my /etc/apt/sources.list):

deb http://debian.linuxmint.com/latest testing main contrib non-free

And after I installed Firefox and Thunderbird, I found myself with a Firefox in Afrikaans and Thunderbird in Arabic. Why this weird combination?

It is because of a bug in the Linux Mint repositories. When you go to install the browsers, they pick the first language pack they find, in alphabetical order!

In order to go back to english, you need to remove the language packs, using the package manager, and then install the english ones:

$ sudo apt-get remove firefox-l10n-af thunderbird-l10n-ar

This command alone actually automatically asked to install the English language packs. You can install also other languages by browsing in the repository:

$ apt-cache search firefox | grep l10n

For some reason, though, after this operations, the browsers did not work, so I tried:

$ sudo apt-get install firefox thunderbird

And everything worked like a charm, in a familiar language.