When I run perl, I get the warning:
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
LANGUAGE = (unset
All the previous answers are wrong. The message is clear - missing locale. The solution is to add the appropriate locale. You do that by editing the /etc/locale.gen file, remove the # sign in front of the locale being reported as missing and then issuing the command:
$ sudo locale-gen
This will actually generate the locales specified in /etc/locale.gen and therefore the message will not be shown.