Change the OSX system language in a script

Question

Manually I just go into the system preferences, change the language ordering, and restart my app so it starts up in the default system language. Then I can run automated tests with the app running in that language.

In the command line, there is a built-in OSX utility languagesetup but this requires sudo and it has to prompt for the new language (i.e. there is no obvious command line option).

I don't know AppleScript well enough to use that but I would be open to using it.

Answer 1

You can open an application using a different language by adding an -AppleLanguages option:

/Applications/Calendar.app/Contents/MacOS/Calendar -AppleLanguages '(de)'

Another option is to add an AppleLanguages array to the property list of the application:

defaults write -app Calendar AppleLanguages -array de; open -a Calendar

languagesetup just changes the first item in the AppleLanguages array in /Library/Preferences/.GlobalPreferences.plist.

Answer 2

There's no need to change the system default language (for most apps, at least). System Preferences » Language & Text doesn't change the system default language anyway, it's just configuration of your user profile.

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The following script writes the list of preferred languages (first German, then English):

defaults write -g AppleLanguages -array de en

Run this, then open your application. Add or remove language IDs as needed.

To list your current language configuration:

$ defaults read -g AppleLanguages
(
    en,
    de
)