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[Python-Dev] Support the /usr/bin/python2 symlink upstream

R. David Murray rdmurray at bitdance.com
Tue Mar 1 23:21:48 CET 2011 
On Tue, 01 Mar 2011 16:26:05 -0500, Eric Smith <eric at trueblade.com> wrote:
> On 3/1/2011 4:19 PM, Kerrick Staley wrote:
> > Hello,
> > There is a need for the default Python2 install to place a symlink at
> > /usr/bin/python2 that points to /usr/bin/python, or for the
> > documentation to recommend that packagers ensure that python2 is
> > defined. Also, all documentation should be changed to recommend that
> > "#!/usr/bin/env python2" be used as the shebang for Python 2 scripts.
> > This is needed because some distributions (Arch Linux, in particular),
> > point /usr/bin/python to /usr/bin/python3, while others (including
> > Slackware, Debian, and the BSDs, probably more) do not even define the
> > python2 command. This means that a script has no way of achieving
> > cross-platform compatibility. The point at which many distributions
> > begin to alias /usr/bin/python to /usr/bin/python3 is due soon, and for
> > the next couple of years, it would be best to use a python2 or python3
> > shebang in all scripts, making no assumptions about plain python, which
> > should only be invoked interactively. This email from about 3 years ago
> > seems relevant: :
> > http://mail.python.org/pipermail/python-3000/2008-March/012421.html
> > Again, this issue needs to be addressed by the Python developers
> > themselves so that different *nix distributions will handle it
> > consistently, allowing Python scripts to continue to be cross-platform.
> >
> 
> I believe we agreed at the language summit last year (or maybe even the 
> year before) that "python" would always be python2.x, and "python3" 
> would be python3.x.
> 
> And by "always" we indeed meant forever. To do otherwise would break 
> scripts even many, many years from now.

It sounds like the distributions aren't going to cooperate with us.
Arch has already switched.  Gentoo will allow the user to switch
/usr/bin/python to point to python3, and I suspect this will become
the default at some point.

I'm not sad about that, myself.

--David
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