[Python-Dev] New update to PEP397 (original) (raw)

[Python-Dev] New update to PEP397 - Python launcher for Windows

Glenn Linderman v+python at g.nevcal.com
Fri Jul 22 01:12:45 CEST 2011

On 7/20/2011 11:35 PM, Mark Hammond wrote:

Virtual commands in shebang lines:

Virtual Commands are shebang lines which start with strings which would be expected to work on Unix platforms - examples include '/usr/bin/python', '/usr/bin/env python' and 'python'. Optionally, the virtual command may be suffixed with a version qualifier (see below), such as '/usr/bin/python2' or '/usr/bin/python3.2'. The command executed is based on the rules described in Python Version Qualifiers below.

I note in passing that '/usr/bin/env python' is hard-coded in the launcher, which conforms to the above documentation. But there is no hard requirement in Unix, if I correctly understand it, that '/usr/bin/env' be separated from 'python' (or whatever) by exactly one space. While I doubt it is frequently used with other than a single space, I think it would be legal to have 2 or 3 or 10 spaces, and maybe even tabs or a mixture, and it would work on Unix... but not in the launcher.

It would somewhat complicate the launcher code to have an additional case to check for /usr/bin/env, skip following white space, and then compare to python, but it would be more robust.

If it is thought that hard-coding a single space covers most of the uses, it should at least be emphasized in the documentation that only commands of than nature containing a single space will work with the launcher.

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