LM_LICENSE_FILE or MGLS_LICENSE_FILE for RTL simulation

I installed Quartus 13.1 Free Edition and the Modelsim-Altera works fine in Windows 10. In Ubuntu however, the application cannot find the license file and I need to point to it as you said. According to this guide: http://cseweb.ucsd.edu/classes/fa10/cse140l/lab/docs/quartus_install.pdf The license.dat file should be somewhere in the root folder but I can't find it there too. Any idea where the license.dat file could be located in a Linux installation? I have tried performing "ls --recursive | grep license.dat" in the quartus installation folder to no avail too.