Error running FreeCAD script using python2 on Ubuntu

[umardastgir]

Hello everyone,

I am having problem understanding how FreeCAD runs using Python. So I have FreeCAD installed on a remote Linux Machine (Runs Ubuntu 18.04). I installed freecad using the following two commands:

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sudo add-apt-repository ppa:freecad-maintainers/freecad-stable
sudo apt-get install freecad

After installing I tried running a small script I wrote:

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import sys
PATHTOFREECADBINFOLDER = "/usr/lib/freecad/lib/"
sys.path.insert(0, PATHTOFREECADBINFOLDER)
import FreeCAD
sys.exit()

I tried running this command using Python 2 (sudo python script.py)
However, I always get the following error:

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import FreeCAD
ImportError: dynamic module does not define init function (initFreeCAD)

I am not sure whats going on as I have freecad installed (directory: /usr/lib/freecad) and it has all the required folders.

Please note that I have tried running this using Python3 and it runs fine! The /usr/lib/ also contains freecad-python3, and if I change the PATHTOFREECADFOLDER to point to this, it run (after creating some symbolic links, as explained in the last comment in the link below)

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https://forum.freecadweb.org/viewtopic.php?t=33684

Can someone please guide me on how to get FreeCAD up and running using python 2?

[kkremitzki]

First off, you generally should not run sudo python or sudo pip, and in this particular case you definitely don't need to do so.

Secondly, with the version you're running, /usr/lib/freecad/lib is a symlink managed by sudo update-alternatives --config freecad, which points to either /usr/lib/freecad-python2/lib or -python3/lib. Try ls -l /etc/alternatives/freecadlib--I'm guessing it's pointed at Python 3, which would explain it working one way and not the other. If that's the case, run the update-alternatives command and pick the other version.

Edit: Also, don't forget to clean up whatever symlinks you created...

Edit2: You also don't need the sys.exit() call in the end, your script will just end and exit normally. The situation where you'd need to use that would be something like:

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if early_exit_condition:
  sys.exit()
 # proceed with normal execution

[umardastgir]

Thanks for your reply.

I tried running the command sudo update-alternatives --config freecad. However, I get the following response:

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There is only one alternative in link group freecad (providing /usr/bin/freecad): /usr/lib/freecad/bin/freecad-python3
Nothing to configure.

How can I change it to point to python 2?

[NormandC]

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sudo apt install freecad-python2

Then use the update-alternatives command again.

[umardastgir]

Thank for the response NormandC. I have installed freecad using apt-get install freecad-python2 and now I have another folder in the /usr/lib directory (freecad-python2). I ran the update-alternatives --config freecad command and chose Python 2 . Now, when I execute the script, I get:

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No modules found in /usr/lib/freecad-python2/Mod
During initialization the error No module named freecad occurred

In the freecad-python2 directory, I only have the lib directory. I also have /usr/lib/freecad-python2 and /usr/lib/freecad directories and /usr/lib/freecad-python3 also contains only lib sub-directory. However, in the /usr/lib/freecad I have other directories (Lib Mod Gui and Ext). Do I need to make symlinks to proceed and solve this error?

[kkremitzki]

Is PATHTOFREECADBINFOLDER still "/usr/lib/freecad/lib/"?

[umardastgir]

No. I modified it to PATHTOFREECADBINFOLDER = "/usr/lib/freecad-python2/lib/" but one strange thing I noticed is that it was giving me the same error for both paths (PATHTOFREECADBINFOLDER = "/usr/lib/freecad-python2/lib/ and PATHTOFREECADBINFOLDER = "/usr/lib/freecad/lib/). Anyways, I created symlinks of the /usr/lib/freecad-python2/Ext/ and /usr/lib/freecad-python2/Mod/ directories to /usr/lib/freecad/Ext/ and /usr/lib/freecad/Mod/ and now everything seems to be working perfectly.

[kkremitzki]

It may be working but you've manually modified a system location which is going to cause you problems down the road. Can you try removing the symlinks and using the original value for that variable, /usr/lib/freecad/lib?

[umardastgir]

I removed the symlinks and changed the variable name to /usr/lib/freecad/lib and now I get the following error:

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No modules found in /usr/lib/freecad-python2/Mod
During initialization the error No module named freecad occurred
Traceback (most recent call last):
  File "3DFileFormatConversion.py", line 127, in <module>
    import importDAE
ImportError: No module named importDAE

[kkremitzki]

Can you paste your full script and full traceback/command output from running it? The error messages are not making sense with regards to what you've shared on the 1st post.