Dave Angel davea at ieee.org
Mon Apr 5 18:15:54 CEST 2010

Wolfman wrote:
> Hello- was hoping someone could give me a hand in permanently setting
> I downloaded Python2.6 to a ThinkPad that came installed with
> Python2.2, and I can not run IDLE as something automatically sets
> TCL_LIBRARY and TK_LIBRARY to C:\IBMTools\Python22\ each time i open a
> new command line window or reboot the machine.
> i have set them to the appropriate Python26 sub-directory via command
> line and IDLE opens just fine and dandy, but as soon as I close the
> command window or reboot computer it sets them back to the
> aforementioned C:\IBMTools\Python22 subdirectory
> how can i permanently SET TCL_LIBRARY and TK_LIBRARY?
> thanks
It can be dangerous to change the system-wide default Python that 
presumably was used for administration on your Thinkpad.  I have a later 
Thinkpad (with XP), and it did not come with any Python.

But if you want to change environment variables persistently on Windows, 
you can go to the Control Panel.  The specifics below are with XP, but 
it'll be similar for other versions between Win2k and later.

     Advanced tab
           Click button labeled Environment Variables
  The upper section contains variables specific to your own logon, while 
the lower panel has variables that will be set for all users.  I believe 
in most cases, a variable defined in both places will get the "user" 
value.  But for PATH, the two are combined into a single, longer 
string.  And perhaps that's true for some others as well.

If you have trouble finding that page ("Environment Variables"), see if 
you can find the System Properties panel.  It has an Advanced tab, and 
you can continue as above.

Once you've set these, any new copy of CMD.exe will get the new values, 
and they are remembered across boot.  However, typing  start from an 
existing DOS box just gets a copy with the same variables you've defined 


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