# Slicer --no-main-window --python-script in windows command prompt not working

**URL:** <https://discourse.slicer.org/t/slicer-no-main-window-python-script-in-windows-command-prompt-not-working/6481>\
**Category:** Development\
**Created:** [April 12, 2019, 3:16pm UTC](https://discourse.slicer.org/t/slicer-no-main-window-python-script-in-windows-command-prompt-not-working/6481 "2019-04-12T15:16:21Z")\
**Posts on this page:** 1\
**Showing post:** 25

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [April 17, 2020, 2:36pm UTC](https://discourse.slicer.org/t/slicer-no-main-window-python-script-in-windows-command-prompt-not-working/6481/25 "2020-04-17T14:36:05Z")

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> [@tbillah](#):
>
> what’s the difference between `SlicerPython` and `PythonSlicer` ?

We had to rename SlicerPython to PythonSlicer, because some Python IDEs (specifically PyCharm, but potentially others) only recognized Python\*.exe files as Python interpreters. We have not removed SlicerPython for backward compatibility but eventually it will go away (see [related issue](https://github.com/Slicer/Slicer/issues/4843)).

> [@tbillah](#):
>
> On the other hand, when an extension (some python packages) is installed using `ExtensionManger` , which python has knowledge of the python packages?

My understanding is that regardless of which launcher (Slicer.exe or PythonSlicer.exe) executes python-real.exe, extensions should be added to path/pythonpath. However, this does not seem to be the case. @jcfr do you know why?

Slicer modules will only be available if you execute SlicerApp-real.exe.

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