<s>[INST] How to avoid .pyc files? Can I run the python interpreter without generating the compiled .pyc files?
 [/INST] From "Whatâs New in Python 2.6 - Interpreter Changes":

Python can now be prevented from
  writing .pyc or .pyo files by
  supplying the -B switch to the Python
  interpreter, or by setting the
  PYTHONDONTWRITEBYTECODE environment
  variable before running the
  interpreter. This setting is available
  to Python programs as the
  sys.dont_write_bytecode variable, and
  Python code can change the value to
  modify the interpreterâs behaviour.

Update 2010-11-27: Python 3.2 addresses the issue of cluttering source folders with .pyc files by introducing a special __pycache__ subfolder, see What's New in Python 3.2 - PYC Repository Directories.
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