A lot of python scripts still use #!/usr/bin/python instead of specifying python2 or python3. I created a quick bash script to replace the python symlink in /usr/bin/python that allows you to use an environment variable PYTHON to indicate whether python refers to python2 or python3:

#!/usr/bin/env bash
test "$PYTHON" != "python2" -a "$PYTHON" != "python3" && unset PYTHON
exec /usr/bin/"${PYTHON:-python3}" "$@"

Then to use it, just export PYTHON=python2 or python3, then run your scripts. The setting will remain in effect until you exit the session.

A script like this would be useful for choosing which version of python should be run for these kinds of ambiguous scripts. It's better than simply pointing the /usr/bin/python symlink to either python version because the setting only takes effect for that particular login session instead of for the whole system. The only problem that I can see with it is that /usr/bin/python is owned by the python package and will be overwritten when the python package is updated.

So I guess what I'm asking is, any chance this script could replace the /usr/bin/python symlink in the python package?

Thanks!