Windows 7 - Windows doesn't seem to keep my system environment variables

jazzvibes · 07-25-2010

Hi all,

As far as I can tell, my problem seems to be quite simple. The solution, however, may not be quite as simple.

The application I am trying to make work is python 3. I also have python 2 installed, but that works fine.

The problem is at the command prompt I would like to be able to type

Code:

python3

and have it launch the python 3 shell. Currently, all I get is

Code:

'python3' is not recognized as an internal or external command,
operable program or batch file.

If I type

Code:

C:\Users\Jazzvibes>python
Python 2.6.5 (r265:79096, Mar 19 2010, 21:48:26) [MSC v.1500 32 bit (Intel)] on
win32
Type "help", "copyright", "credits" or "license" for more information.
>>>

it already launches python 2 (which is correct).

I have already tried to put python3 as a system and user environment variable, in As far as I know the same way as python is set up. I changed this at the system properties window and then going to environment variables on the "Advanced" tab.

if I type

Code:

set

at the command prompt, I believe it should confirm this (please correct me if i'm mistaken)

Code:

python=C:\Python26\python.exe
python3=C:\Python31\python.exe

So, have I done something wrong, or left a step out? Please let me know if you need more info.

I should point out that typing a hard link to python3 using the address above does work, but I would like the shortcut for convenience (and to work out why it doesn't work in the first place)

My system for the record is Windows 7 64bit. Although both python installations are 32 bit versions (although i'm fairly sure that is trivial)

Regards,
Jazzvibes

SailingNut · 07-26-2010

I have never done anything like you are attempting to do. (Setting up an alias for an executable)

I would tackle the problem by creating .cmd or .bat files that are in the path that then calls the proper executable and passes along all parameters.

For example, your batch file for python 3 would be called python3.bat (captain obvious to the rescue

) and you would include the following code:

Code:

 
C:\Python31\python.exe %1 %2 %3 %4 %5 %6 %7 %8 %9

I'm not sure you need to include all of those command line parameter pass-throughs but it can't hurt.

Ztruker · 07-26-2010

Add C:\Python31 to the end of the existing path environment variable. You do this by adding a ; (semi colon) then the path to C:\Python31. That will make it accessible from a Command Prompt.

strollin · 07-26-2010

In order to access your environment variable from the command line you need to bracket it with % like this: %python3%. In order to use the environment variable in a batch file you need to bracket it with %% like this: %%python3%%

jazzvibes · 07-27-2010

Woah thanks! Some good working solutions.
ZTruker has suggested the one that is most like the original though. I looked in the path variable to find C:\Python26, and added C:\Python31 and now it works exactly as expected.

the batch file method and the %python3% method both worked well too.

Windows 7 - Windows doesn't seem to keep my system environment variables

Windows doesn't seem to keep my system environment variables problems?