Hello Helena
I found this message: http://osgeo-org.1803224.n2.nabble.com/g-mapset-unable-to-read-GIS-LOCK-env-variable-td3121705.html
But I'm not sure if this is still applicable. Ask Glynn or Hamish or even DAniel about this. I searched in init.bat and I did not found anything about GIS_LOCK in there.
About your problem in Linux that I cannot help you.
Antonio Rocha
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