How to install Debian 10 (Buster) in English language but with German locales?

Question

Based on this question considering Debian 9 (Stretch), maybe there are some updates available.

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I want to use English language with German locales.

Is there an option available to select this configuration already during Debian installation (maybe within Advanced options -> Expert install)?

Up to now I would use the following approach:

1. Choose language: English - English
2. Country, territory or area: other -> Europe -> Germany
3. Country to base default locale settings on: de_DE.UTF-8

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Unfortunately, pairing English language with German locales is not provided by default as you can also see in the next screenshot:

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However, Ubuntu and its derivates provide such an option already during installation in the next step after selecting the desired language:

Afterwards, checking locale leads to:

user@pc:~$ locale
LANG=en_US.UTF-8
LANGUAGE=
LC_CTYPE="en_US.UTF-8"
LC_NUMERIC=de_DE.UTF-8
LC_TIME=de_DE.UTF-8
LC_COLLATE="en_US.UTF-8"
LC_MONETARY=de_DE.UTF-8
LC_MESSAGES="en_US.UTF-8"
LC_PAPER=de_DE.UTF-8
LC_NAME=de_DE.UTF-8
LC_ADDRESS=de_DE.UTF-8
LC_TELEPHONE=de_DE.UTF-8
LC_MEASUREMENT=de_DE.UTF-8
LC_IDENTIFICATION=de_DE.UTF-8
LC_ALL=

=> This is exactly what I want in Debian.

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Question:

Is there any possibility to choose the desired configuration already during installation? Or is it only possible to adjust this after completing the whole installation progress?

Answer 1

If you choose the expert installer you can add one or more additional locales and then choose the default locale, but you need to change your LC_XXX variables manually as described by Stephen Kitt.

Regarding the locale settings this is the same as using the default installation method and running sudo dpkg-reconfigure locales afterwards.

The selections would look like this:

1. In grub choose Advanced options -> and Graphical expert install or Expert install:
2. Select a language: English - English
3. Select your location: other -> Europe -> Germany
4. Configuring locales: United States - en_US.UTF-8
5. Configuring (additional) locales: de_DE.UTF-8
6. Select the default locale for the installed system: en_US.UTF-8

And modify the individual locale settings as needed when the installation completes.

To update the global locale settings you could use:

sudo update-locale LANG=en_US.UTF-8 $(printf 'LC_%s=de_DE.UTF-8 '\
 NUMERIC TIME MONETARY PAPER NAME ADDRESS TELEPHONE MEASUREMENT IDENTIFICATION)

Or add the variables to your local shell initialization file. To add the German settings to your ~/.bashrc if the default locale is en_US.UTF-8, you could use:

printf 'export LC_%s=de_DE.UTF-8\n'\
 NUMERIC TIME MONETARY PAPER NAME ADDRESS TELEPHONE MEASUREMENT IDENTIFICATION >> ~/.bashrc