I understand, but is it at least possible to officially recommend that python, python2, and python3 all exist, that distributions point python to python2, and that scripts specify which of python2 and python3 they are using? This would create a redundant system that doesn't avoids problems even if distributions do decide to ignore the second point. If not, can someone point me to official documentation that recommends that python always invoke Python2, so that I can take the case up with the Arch developers?
Thanks,
Kerrick Staley
On Tue, Mar 1, 2011 at 3:26 PM, Eric Smith
<eric@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.
And by "always" we indeed meant forever. To do otherwise would break scripts even many, many years from now.
Eric.
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