Disable output buffering

Is output buffering enabled by default in Python's interpreter for sys.stdout?

If the answer is positive, what are all the ways to disable it?

Suggestions so far:

1. Use the -u command line switch
2. Wrap sys.stdout in an object that flushes after every write
3. Set PYTHONUNBUFFERED env var
4. sys.stdout = os.fdopen(sys.stdout.fileno(), 'w', 0)

Is there any other way to set some global flag in sys/sys.stdout programmatically during execution?

---

_{If you just want to flush after a specific write using print, see How can I flush the output of the print function?.}