# External calling at Slicer 3D

**URL:** https://discourse.slicer.org/t/external-calling-at-slicer-3d/136
**Category:** Development
**Created:** [April 17, 2017, 10:18pm UTC](https://discourse.slicer.org/t/external-calling-at-slicer-3d/136 "2017-04-17T22:18:50Z")
**Posts on this page:** 1
**Showing post:** 1

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### Author: ![Alba\_Garcia\_de\_la\_Ca](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/alba_garcia_de_la_ca/32/181_2.png) [@Alba\_Garcia\_de\_la\_Ca](https://discourse.slicer.org/u/Alba_Garcia_de_la_Ca)
#### Post date: [April 17, 2017, 10:18pm UTC](https://discourse.slicer.org/t/external-calling-at-slicer-3d/136/1 "2017-04-17T22:18:50Z")

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Hi everybody,

I am programming an extension module for Slicer 3D. In one step I need to call an external command (Elastix). At this point is when I obtain the following error:

 ![](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/1X/6e7cf603bea688a3821efdb228bd5f65599bcb13.jpg)

I have not been able to solve it yet. Do you know how get rid of this problem? It works when I execute the call in a terminal.

I look forward to hearing from you. Thanks in advance.

Sincerely,

Alba.

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