[Python-Dev] Another update for PEP 394 -- The "python" Command on Unix-Like Systems

Jason Swails jason.swails at gmail.com
Thu Feb 14 07:35:49 EST 2019


> On Feb 14, 2019, at 3:44 AM, Antoine Pitrou <solipsis at pitrou.net> wrote:
> On Thu, 14 Feb 2019 00:57:36 -0500
> Jason Swails <jason.swails at gmail.com> wrote:
>> I literally just ran into this problem now.  Part of a software suite I've
>> written uses Python to fetch updates during the installation process.  Due
>> to the target audience, it needs to access the system Python (only), and
>> support systems as old as RHEL 5 (Python 2.4 and later, including Python
>> 3.x in the same code base, using nothing but the stdlib).  The shebang line
>> was "#!/usr/bin/env python"
>> It's been working for years, but was only now reported broken by a user
>> that upgraded their Ubuntu distribution and suddenly had no "python"
>> executable anywhere.  But they had python3.
>> I suspect suddenly not having any "python" executable in a Linux system
>> will screw up a lot more people than just me.  The workaround was ugly.
> I'm not sure what you mean.  Isn't the workaround to install Python 2
> in this case?

I release the software, so the problem is not my machine, it’s others’. The installation process also fetches a local miniconda distribution for the Python utilities that are part of the program suite (and the python programs are optional and typically not installed when this suite is deployed on a supercomputer, for instance). But the software needs to check for updates before it does any of that (hence my concern — this script needs to be able to run before the user does *anything* else, including installing dependencies). 

This would also be the first time we’d have to give different installation instructions for different versions of the same Linux distro. 

The workaround from a users perspective is simple for me, but I can’t make that same assumption for all of my users. This is an impediment to keeping the user experience as simple as possible. 

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