Error while installing xilinx on Ubuntu

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http://ubuntuforums.org – While installing Xilinx on Ubuntu 12.04, It shows actually the error 'Could not create destination path /opt/Xilinx/13.4/ISE_DS'.. The software consists of executable text file called xsetup. I run that file using terminal. my root accout is disabled.. and With out using root account, how to install it actually ? (Hardware)