A simple script to get a list of all locales installed on the server:

<?php //to display ALL installed locales
system('locale -a');
?>

If you slightly modify the script, you can view only the locales for a specific language (ru - Russian, en - English):

<?php //to display only locales in UTF-8
system('locale -a | grep UTF');
?>

Copy this script into a file named test.php, upload it to the website folder, and open yoursite.com/test.php