As it happens, the os.listdir() problem is just the tip of the iceberg of Python 3's Unix problems . Here are two more ways that it helps Unixprogrammers, from the release notes :

Some system APIs like os.environ and sys.argv can also presentproblems when the bytes made available by the system is notinterpretable using the default encoding. Setting the LANG variableand rerunning the program is probably the best approach.

Since the release notes are not explicit, let me fill them in