On Tue, Jun 15, 2010 at 4:26 PM, Benjamin Kaplan
<benjamin.kap...@case.edu>wrote:
> On Tue, Jun 15, 2010 at 3:55 PM, Dan Stromberg <drsali...@gmail.com>
> wrote:
> >
> > I don't think #!/usr/bin/env python is the right thing - unless a script
> > really doesn't care much what version of python it gets.
> >
> > I used to #!/usr/bin/env everything, but I've been updating my old
> scripts
> > not to. It's just too much trouble, despite the one minor simplification
> it
> > provides.
> >
> > My Ubuntu 10.04 system has a mix of the two, but there are more
> > #!/usr/bin/python's. That concerns me a bit, because I've needed to
> install
> > a half dozen versions of python in the past, and soon will do so on this
> > machine. Of course, I rarely change my $PATH to include one of these
> > alternative python's (which is probably the salient issue), but I don't
> want
> > to be stuck being unable to do so if the need does arise.
> >
> > I spent a year working in PowerShell, to my surprise. What a pain it was
> > not being able to install more than one version at the same time. May
> > Python never have that problem!
> >
>
>
> #!/usr/bin/python doesn't mean you care about what version of Python
> you use, it means you care about what *location* you use.
Nah. It means you want the system default. To an extent.
> If I'm on
> Ubuntu 8.04, it's Python 2.5. If I'm on Ubuntu 10.04, it's Python 2.6.
> And what happens if you bring your script to a distribution that puts
> its python installs in /usr/local/bin?
>
Few to none will. There was a discussion way back in Linux history about
putting standard utilities in /usr/local. It was slapped down. People
wanted it because their Suns and HP's had everything in /usr/local, but
wisely, things were relocated to /usr.
> If you care what version of Python you get, then do
> #!/usr/bin/env python2.6
>
That's not a bad suggestion, but I rarely put my python builds on my $PATH,
and don't really see that changing (but would like to retain the ability in
case I do need it). My main reason for this is that sometimes python will
inspect your $PATH looking for its standard library. Or at least, it did at
one time.
>
> which will run it under a specific version of Python. All Python
> installs include the pythonX.X executable, and then one of those
> executables is symlinked to python.
Yes, this is a good thing to do.
> Common convention on Linux and Mac
> OS X (probably other Unix-based systems as well) is to leave
> /usr/bin/env python pointing to the system's default Python install
> (wherever it is) and to altinstall the other versions of Python (so
> you access them by specifying the version number).
The thing is, this doesn't really point to anything. Each user can change
their $PATH variable - system scripts shouldn't break because of something
so common.
> This is what Ubuntu
> does if you install multiple versions through the package manager.
>
Did you read what I posted?
Ubuntu 10.04 (Lucid Lynx) is mostly using #!/usr/bin/python.
/usr/bin has:
1 #!/usr/bin/envpython2.6
1 #!/usr/bin/python3
1 #!/usr/bin/python -OOt
2 #!/usr/bin/python2.6-dbg
4 #!/usr/bin/env python
12 #!/usr/bin/python2.6
14 #!/usr/bin/envpython
114 #!/usr/bin/python
Lucid has 2.6 (system default) and 3.1.
>
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