windows batch-file environment-variables setx

How to use setx command in a windows batch file

I am trying to create a windows batch file to automatically set the environment variable to use python 2.4 or python 3.3.

Both python 2.4 and 3.3 are installed on my system. Here is my code:

::To toggle between Python24 and Python 33
@echo on
if (%PYTHONHOME:~-2%) == "24" (setx PYTHONHOME "C:\Python33" && setx PATH %PATH:Python24=Python33% ) else (setx PYTHONHOME "C:\Python24" && setx PATH %PATH:Python33=Python24% )
pause

To start with I have PYTHONHOME set to C:\Python24

But the above script gives the following error:

SUCCESS: Specified value was saved.
ERROR: Invalid syntax. Default option is not allowed more than '2' time(s).
Type "SETX /?" for usage.

My PYTHONHOME still points to python 24 and nothing is changed. The setx command does not change the environment variable. What is causing this error?

Solution

The Windows command line error:

ERROR: Invalid syntax. Default option is not allowed more than '2' time(s).
Type "SETX /?" for usage.

Summary:

You are using a setx command and assigning it multiple tokens when only one is allowed.

How to reproduce this error on Windows:

Open a windows cmd terminal and enter these commands. This throws the error:

C:\Users\Charity>setx FANCYPANTS string with spaces

ERROR: Invalid syntax. Default option is not allowed more than '2' time(s).
Type "SETX /?" for usage.

Do the same command, but quote your string like this:

C:\Users\Charity>setx FANCYPANTS "string with spaces quoted"
SUCCESS: Specified value was saved.
C:\Users\Charity>

The variable was set, restart the cmd terminal here to load changes.

C:\Users\Charity>echo %FANCYPANTS%
string with spaces quoted

The environment variable is saved. Now delete it.

C:\Users\Charity>setx FANCYPANTS ""
SUCCESS: Specified value was saved.

restart the cmd terminal here to load changes. Print contents again.

C:\Users\Charity>echo %FANCYPANTS%
%FANCYPANTS%

the variable FANCYPANTS was deleted and no longer exists.