Use Python 3 in scripts

[Ross Burton]

Now that Python 2 is EOL, would it be sensible to change the hashbangs in all the scripts to use #! /usr/bin/env python3?

There's an increasing number of systems without Python 2 at all, and they don't need to have a python binary available. For example, my Debian chroot for development in doesn't have a /usr/bin/python but has Python 3 installed.

[Marc Herbert]

https://lwn.net/Articles/780737/ Revisiting PEP 394

[Marc Herbert]

would it be sensible to change the hashbangs in all the scripts to use #! /usr/bin/env python3?

Isn't this equivalent to dropping support for python2? Which some people will keep using even after it stops being supported.

[Ross Burton]

They'd still be able to use python2 genconfig. Using the unversioned name breaks for people without an unversioned symlink, so someone's going to be upset either way.

[Marc Herbert]

Just for fun, sharing a very "creative" workaround I've seen once:

#!/bin/sh
"true" '''\'
if [check some stuff]; then
    exec python2 "$0" "$@"
else
    exec python3 "$0" "$@"
fi
exit 127
'''
import ...

[Ulf Magnusson]

I'm fine with changing the hashbangs to use python3. Installing the wheels on Python 2 should still work, because entry_points creates bounce scripts with their own hashbangs, and manually running python script.py on older systems probably isn't too bad. More important to have stuff be seamless on modern systems.

I wonder if there are systems where python points to Python 3 and python3 isn't available. Probably rare at least, going on https://www.python.org/dev/peps/pep-0394/#for-python-runtime-distributors.