Mining Litecoins as User in Debian I followed this tutorial https://litecoin.info/Debian_Linux_cryptocoin_mining_rig_setup_guide and set up a Mining rig (Debian 6.0.10). Sometimes I modified it (downloaded later graphics drivers than in the Tutorial sugestet etc) but it works and I can mine on a pool.

But I can mine only if I log in as root. If I log in as a normal user and type cgminer --verbose -T, I get the following error:

 [2015-02-15 22:36:50] Started cgminer 3.7.2                    
 [2015-02-15 22:36:50] Loaded configuration file /home/martin/.cgminer/cgminer.conf                    
No protocol specified
No protocol specified
No protocol specified
 [2015-02-15 22:36:50] CL Platform 0 vendor: Advanced Micro Devices, Inc.                    
 [2015-02-15 22:36:50] CL Platform 0 name: AMD Accelerated Parallel Processing                    
 [2015-02-15 22:36:50] CL Platform 0 version: OpenCL 2.0 AMD-APP (1642.5)                    
 [2015-02-15 22:36:50] Error -1: Getting Device IDs (num)                    
 [2015-02-15 22:36:50] clDevicesNum returned error, no GPUs usable                    
 [2015-02-15 22:36:50] All devices disabled, cannot mine! 


I tried setting all privileges in the folders in root - which are used for litecoin mining - to 777 and to change the owner to the usual user, but it didn't work. I copied the file /root/.cgminer/cgminer.conf to /home/user/.cgminer/cgminer.conf, set the user and the right to this file, but this didn't solve the problem too. 

But why can only root access the OpenCL functions which are used, why can not the normal user do so?

Thank you.
You should be able to add your current user to the plugdev group in Linux to be able to access the GPU as a standard user.  This can be accomplished by the following command:


  sudo usermod -G plugdev -a whoami


There may be some additional bits of information that are relevant in the README on the cgminer website.