I'm setting up PyDev for Eclipse, and I have to choose a version of Python for the interpretor. I want to use Python3, and I've been using python3 as my interpretor, so I thought /usr/bin/python3 would have been the obvious choice. However, another option there is python3mu. I ran this in the terminal and it seemed to function exactly like python3. My questions are: Which one is the correct one to use as the interpretor for Eclipse? and What is the difference between the two?

EDIT: Just wanted to let you guys know that my google-fu was not good enough to find out what python3mu was.

  • Check this out link
    – tomasz74
    Nov 11, 2012 at 21:32
  • @tomasz74 Ahh, so this is a version without many of the modules added on by default? And so I should use the regular one right? Also, just put that link in an answer, and I'll give you the green check mark.
    – Amndeep7
    Nov 11, 2012 at 21:34
  • No, 'mu' has nothing to do with minimal Nov 11, 2012 at 21:36
  • 1
    Related question on Stack Overflow: Difference between python3 and python3m executables.
    – wjandrea
    Nov 12, 2017 at 5:40

1 Answer 1


In python 3, some compile options (the abi flags) are reflected in the binary name and the name of cached bytecode in __pycache__ directories. mu means--with-pymalloc and --with-wide-unicode

See also http://docs.python.org/dev/library/sys#sys.abiflags and http://www.python.org/dev/peps/pep-3149/

  • I've looked at the links, and it appears that these only apply to libraries and such. Maybe I'm wrong, but I don't think that that applies to the version of Python you're running. Could you please explain a bit more?
    – Amndeep7
    Nov 11, 2012 at 21:41
  • 1
    ABI means "Application Binary Interface". This includes signatures of all functions and constants as used in a program and is a sort of contract between libraries and applications. e.g. in --with-pymalloc builds, memory allocation works differently. If libraries don't know this about the binary, they'll try to do things that make python crash :) Nov 11, 2012 at 21:45
  • As a programmer who does not work much with python (read and write files only), do I need the python3..m or can I remove it?
    – Timo
    Jan 1, 2021 at 13:36

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