I'm using freesurfer v5.3.0 and having problems with the number of threads opened by `mri_em_register`. It automatically opens up as many threads as there are in the system, but I need to limit that. 

I have seen this post with the same problem: MailScanner has detected a possible fraud attempt from "secure-web.cisco.com" claiming to be https://www.mail-archive.com/freesurfer@nmr.mgh.harvard.edu/msg41604.html

In the end, it seems to be solved by setting OMP_NUM_THREADS to 1 in the mri_em_register script, but it is a binary file. I don't know how to set it. 

Kind regards,

Gunes