Hi folks,
In the language summit discussion about the /usr/bin/python symlink
back in 2015 [1], Matthias mentioned the possibility of using the
"alternatives" system to manage what an unqualified reference to
"/usr/bin/python" meant in a traceable way.
While Guido was reluctant to support distros or sysadmins providing a
system level /usr/bin/python -> /usr/bin/python3 link when Petr
Viktorin subsequently updated PEP 394 to allow for the symlink not
existing at all [2], it's now public info that the recommendation [3]
(which I agree with) from Red Hat's Python maintenance team for the
Python 3.6 based RHEL 8 release is for sysadmins to use the
alternatives system to explicitly choose which option they consider
most appropriate for their organisations (i.e. no unqualified symlink,
link to Py3, or continue linking to Py2 for now).
The other thing that's changed since the PEP was last updated is that
Brett Cannon wrote a version of the Python Launcher that runs on *nix
systems instead of Windows: https://crates.io/crates/python-launcher
This means that for distros that choose to package that launcher,
they'll have the option of making /usr/bin/python a symlink to
/usr/bin/py instead of a direct link to any particular version.
Given those developments since the last update, is there anything we
want to change in the PEP's current recommendations? Or do we think
Petr's last set of updates are sufficient for the time being, and we
can instead take another look once we're further through 2019 and the
2020 support deadline for Python 2.7 is getting closer?
Cheers,
Nick.
P.S. "Nah, leave the PEP alone for now" is a perfectly reasonable
response, as the updates in [2] already covered the main cases we were
concerned about for Fedora/RHEL, which were the switch to not shipping
/usr/bin/python by default, and the switch to making end users
reconfiguring /usr/bin/python to refer to python3 an officially
supported user action at the distro level.
[1] https://lwn.net/Articles/640296/
[2] https://github.com/python/peps/pull/630
[3] https://developers.redhat.com/blog/2018/11/14/python-in-rhel-8/
--
Nick Coghlan | ncoghlan(a)gmail.com | Brisbane, Australia
