warning: setlocale LC_ALL

What is LC_ALL:

LC_ALL is the environment variable that overrides all the other localisation settings 

The value 'LC_ALL=C' is essentially an English-only environment that specifies the ANSI C locale.

You'll typically set $LANG to your preference. The individual LC_xxx variables override a certain aspect. LC_ALL overrides them all. The locale command, when called without argument gives a summary of the current settings.

LC_* var priority

LC_ALL > LC_* > LANG

locale def file:

/usr/share/i18n/locales
vi /etc/default/locale

LANG & LANGUAGE

LANG: specifies the default locale for all unset locale variables
LANGUAGE: most programs use this for the language of its interface

warning: setlocale LC_ALL solution

export LC_ALL="en_US.UTF-8" export LANGUAGE="en_US.UTF-8"