Why is overriding the LANG environment variable not changing the language for me?

Question

I'm trying to run an application in another language as my current environment. To start out simple, I wanted to change the language of ls.

Here's what I read all over the place (see below for related questions): set LANG to one of the supported locales, e.g.:

LANG=nl_NL.UTF-8 ls /nonexistent

to have it show Dutch (NL) output.

However, I still get English output:

$ LANG=nl_NL.UTF-8 ls -al /nonexistent
ls: cannot access /nonexistent: No such file or directory

My current environment:

$ locale
LANG=en_GB.UTF-8
LANGUAGE=en_GB:en
LC_CTYPE="en_GB.UTF-8"
LC_NUMERIC="en_GB.UTF-8"
LC_TIME="en_GB.UTF-8"
LC_COLLATE="en_GB.UTF-8"
LC_MONETARY="en_GB.UTF-8"
LC_MESSAGES="en_GB.UTF-8"
LC_PAPER="en_GB.UTF-8"
LC_NAME="en_GB.UTF-8"
LC_ADDRESS="en_GB.UTF-8"
LC_TELEPHONE="en_GB.UTF-8"
LC_MEASUREMENT="en_GB.UTF-8"
LC_IDENTIFICATION="en_GB.UTF-8"
LC_ALL=

To be sure, I've checked:

• The locale is supported:

  $ grep nl_NL /usr/share/i18n/SUPPORTED 
  nl_NL.UTF-8 UTF-8
  nl_NL ISO-8859-1
  nl_NL@euro ISO-8859-15
  

• The locale is generated:

  sudo locale-gen nl_NL.UTF-8
  

  and sudo dpkg-reconfigure locales also shows it's generated.

• Installed the Dutch language pack (already installed):

  sudo apt-get install language-pack-nl
  

What else have I tried?

• Using export to set both LANG and LANGUAGE instead of prepending the command.
• Setting also LC_ALL.

Ironically, some (only some!) GUI applications are actually in Dutch, but I haven't configured that at all!

I'm on Kubuntu 12.04(.2), as far as that matters.

Similar questions (to no avail):

• Is it possible to change language for user interface temporarily?
• How to override the system locale on a single command?
• Temporarily change language for terminal messages/warnings/errors (demonstrated to be working, but not working for me)
• How do I add locale to ubuntu server?

What's wrong on my system? Where to debug this further?

Answer 1

Because LANGUAGE, which takes precedence over LANG, is set and unchanged.

$ LANGUAGE=nl ls /nonexistent
ls: kan geen toegang krijgen tot /nonexistent: Bestand of map bestaat niet

More info is in the GNU gettext documentation:

GNU gettext gives preference to LANGUAGE over LC_ALL and LANG for the purpose of message handling, but you still need to have LANG (or LC_ALL) set to the primary language; this is required by other parts of the system libraries.