Originally Posted by abefroman
Can files/directories have Greek characters? If I selected English when installed Linux?
Yes, as long as you use a locale that uses a character encoding
that is a superset of Greek or includes Greek as part of it. The character encodings that fulfill such condition are those based on UNICODE, such as UTF-8 and UTF-16. The former is used mostly in Linux distros, the latter is used in MS Windows.
So answering your question, if you choose an English locale that uses UTF-8 as character encoding (say, en_US.utf8), you'll be able to use Greek characters (and Chinese, Cyrillic, whatever). If you have already created the directories/files under a different encoding, you can fix the damage using a utility such as convmv.