In a fresh Ubuntu, not having the locales setup, it shows warning every time while installing any software/library and while stopping/restarting as well.
You can setup the required locales easily.
The following example shows the simple steps to setup the en_IN UTF-8 locale.
Edit or Create the file /var/lib/locales/supported.d/local and add the required local in the file as follows
you can add more locales in new lines.
reconfigure your system’s locales by issuing the command