[Python-Dev] PEP 394 request for pronouncement (python2 symlink in *nix systems) (original) (raw)

Antoine Pitrou solipsis at pitrou.net
Sun Feb 12 16:21:53 CET 2012

On Sun, 12 Feb 2012 19:04:30 +1000 Nick Coghlan <ncoghlan at gmail.com> wrote:

PEP 394 [1] aims to document our collective recommendation for allowing shebang lines to specifically request some version of 2.x, without requiring that it be exactly 2.7 (or 2.6, etc).

I'd let this drift for a while, but the imminent release of 2.7.3 makes it necessary to push for a final pronouncement. Kerrick has the necessary Makefile.pre.in patch up on the tracker [2] to add the hard link for the python2 name.

Why hard links? Symlinks are much more introspectable. When looking at a hard link I have no easy way to know it's the same as whatever other file in the same directory.

I also don't understand this mention:

“The make install command in the CPython 3.x series will similarly install the python3.x, idle3.x, pydoc3.x, and python3.x-config binaries (with appropriate x), and python3, idle3, pydoc3, and python3-config as hard links. This feature will first appear in CPython 3.3.”

This feature actually exists in 3.2 (but with a symlink, fortunately):

$ ls -la ~/opt/bin/pydoc3 lrwxrwxrwx 1 antoine antoine 8 oct. 15 21:24 /home/antoine/opt/bin/pydoc3 -> pydoc3.2*

Regards

Antoine.

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