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Hi Freesurfers, 
I’m trying to use mergecontrasts-sess to merge two contrasts of an analysis, but  I get this: 
mergecontrasts-sess: Command not found.

I tried with other Fs-Fast commands and they work. I am running on a Ubuntu 18.04, 64 bit. I downloaded the 6.0.0. Freesurfer
version from the official page.

Could you help me?
Thanks a lot 

Paula