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Groups > comp.lang.python > #51296

Re: Python Script Hashplings

Date 2013-07-26 11:47 +0100
From Tim Golden <mail@timgolden.me.uk>
Subject Re: Python Script Hashplings
References <51F12B41.3050004@Gmail.com> <51F12E31.1070502@mrabarnett.plus.com> <51F2517D.2070009@Gmail.com>
Newsgroups comp.lang.python
Message-ID <mailman.5143.1374835648.3114.python-list@python.org> (permalink)

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On 26/07/2013 11:37, Devyn Collier Johnson wrote:
> 
> On 07/25/2013 09:54 AM, MRAB wrote:
>> On 25/07/2013 14:42, Devyn Collier Johnson wrote:
>>> If I execute a Python3 script with this haspling (#!/usr/bin/python3.3)
>>> and Python3.3 is not installed, but Python3.2 is installed, would the
>>> script still work? Would it fall back to Python3.2?
>>>
>> Why don't you try it?
>>
>>> I hope Dihedral is listening. I would like to see another response
>>> from HIM.
>>>
>>
> Good point, but if it falls back to Python3.2, how would I know? Plus, I
> have Python3.3, 3.2, and 2.7 installed. I cannot uninstall them due to
> dependencies.

Devyn, I'm not a *nix person so someone can point out if I'm wrong, but
my understanding is that the shebang line (or whatever you want to call
it) just tells the shell: run this command to run this file. So you can
put "#!/usr/bin/fish-and-chips" as the first line and it will try to run
the file using /usr/bin/fish-and-chips.

If you put #!/usr/bin/python3.3 the shell will use the executable
/usr/bin/python3.3. It doesn't know or care about Python or its
versions: it won't go looking for some alternative binary. If
/usr/bin/python3.3 isn't there, the shell will fail to run the code with
some kind of error message.

If you or your package manager symlink /usr/bin/python3 to whatever the
latest Python 3.x is on your system then you can safely use
/usr/bin/python3 throughout and let the symlink do the work!

TJG

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Re: Python Script Hashplings Tim Golden <mail@timgolden.me.uk> - 2013-07-26 11:47 +0100

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