Trelis 16 run python script and GEOCUBIT

Hello everyone,
I am doing my research about fault these days by using SPECFEM3D and Trelis16.
My computer OS enviornment is Ubuntu under virtual machine.
I would use some python script in directory /SPECFEM3D/CUBIT_GEOCUBIT/ , but I got some problem here.
I input those command into Trelis script tab and run, but some error appeard, the model were constructed but not very correctly. At the same time, I run these script in Trelis command tab but it said XX can not be found. Does it means I have not set a correct working directory of Python? If it is, How can I let Trelis to recognition these scripts in GEOCUBIT?I am not very clear about that(I tried setting enviornment variables in ubuntu but not works.Sorry I am newbie in Linux.).
Who know some details about this problem? I have stuck here for half month.Please give me some help. I am looking forward and very grateful for reply.Thank you.