On Fri, 4 Aug 2017, Scott Kitterman wrote:
If the primary concern is what happens when a user types "python", then can we address that in command-not-found and leave /usr/bin/python out of it?
Debian doesn't ship command-not-found by default. One other approach here would be to have /usr/bin/python exec python3 if it's run interactively -- that is, if isatty(0) -- and print an error message and exit otherwise. I don't think it is too bad to print an error message instead of failing the exec, since that's equivalent to what happens if you're missing a shared library or something: the exec succeeds, but the dynamic loader prints an error and exits nonzero.
Ship this /usr/bin/python with python3-minimal, and have the python-minimal package divert it and replace it with the current /usr/bin/python (a symlink to python2.7). This way we can build systems with Python 3 only that behave reasonably, but also allow doing `apt-get install python` to cause /usr/bin/python to start working again.
However, I feel like another reason to care about /usr/bin/python is so that sysadmins responsible for multiple platforms can continue writing #!/usr/bin/python (or #!/usr/bin/env python) scripts and use the same script on all their machines. If I can't do this and need platform-specific scripts, I might as well use some other language or ship compiled binaries. Keeping Python viable for this use case is a large part of why I originally proposed pythonmux: I can write scripts that declare that they're polyglot Python 2/3 and work on both Python 2-only and Python 3-only systems, but a Python 2 script using #!/usr/bin/python will give me an error (as it should!) if there's no Python 2 installed on the machine.
Last time I checked (2015), entirely reasonable versions of RHEL and macOS both shipped only Python 2 and not Python 3. Is it likely to be the case that all UNIXy OSes within security support in 2019 or 2020 will have a /usr/bin/python3 (preferably 3.3+)? If so, that's a viable option. I just want my best migration path from #!/usr/bin/python to not involve rewriting my scripts in Go.
-- Geoffrey Thomas https://ldpreload.com geofft@ldpreload.com