How to use setx command in a windows batch file

Question

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?

Answer 1

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.