I have 2 versions of python installed on windows, 2.7.3 and 3.3. Some of my scripts are 2.x and some 3.x. Is there an easy way when executing these scripts from a command line to direct them to the appropriate interpreter?
3 Answers
Note: For Windows use the new Windows Python launcher (available with Python 3.3 and downloadable here for earlier releases) which recognizes Unix shell shebangs. You can read about it here.
Most Linux distributions will create python2 and python3 aliases for the installed Python 2.x and Python 3.x interpreter (if not you can just create the symbolic links yourself anywhere on your $PATH, the env command will take care of finding them), so you should just need to set the appropriate interpreter as the first line of your script:
#!/usr/bin/env python2
or
#!/usr/bin/env python3
This will direct the shell to use the appropriate interpreter, if you set the script files to be executable and just invoke them directly on the shell. E.g.:
$ chmod +x script.py
$ ./script.py
3 Comments
Pedro Romano
The poster didn't mention that Windows was the OS initially. :(
U2ros
Yes, but its still possible to mess with PATH and aliases, i ll give it a shot
Pedro Romano
@U2ros See my improved answer with the reference to the new Windows Python launcher. That should be the ideal solution.
Try this first: I am on OS X, but when I want to use Python 2.6 instead of Python 2.7 (its a numpy/scipy thing), I simply run python2.6 whatever.py to run whatever.py in Python 2.6. Try that first.
If that doesn't work, then you can use virtualenv - the virtual environment builder for Python.
http://pypi.python.org/pypi/virtualenv
I am sure there are similar alternatives, too.
1 Comment
U2ros
On ubuntu, im doing exactly that ;>
Pedro Romano's answer is the most elegant way of doing this.
But if you don't want to download and install the Python launcher, create a batch file as described below. You can also create a shortcut, copy C:\Python27\python.exe to C:\Python27\python27.exe, etc.
I'm guessing C:\Python27 and C:\Python33 are already on your system path. If so, you can create a batch file called python2.7.bat in C:\Python27\ which contains:
C:\Python27\python.exe %1
and a similar file (e.g. python3.3.bat) in C:\Python33\
Now, you can run python2.7 script.py from anywhere in command prompt and it should work :)
python2andpython3, however you don't mention what OS or installation packages you're using.