Care to share some more context? What command are you using in the x-term? Where is located the archive you want to uncompress?

At any rate, erminig-ng cannot be installed in MyDocs (or any subdirectory of it), since it relies on the executability of a library that cannot be there....For the moment the best location is directly in /home/user, at least until I manage to properly package it in a .deb.