What gcc versions are available within the farm Golias?

A: Various gcc versions are available through cvmfs in the directory /cvmfs/sft.cern.ch/lcg/contrib/gcc. Set the following command to list all installed gcc versions:

[username@ui3 ~]$ ll /cvmfs/sft.cern.ch/lcg/contrib/gcc

Simply run setup.sh (or setup.csh) for a chosen gcc version to set a required enviroment.

Example:

[username@ui3 ~]$ source /cvmfs/sft.cern.ch/lcg/contrib/gcc/4.9.3/x86_64-slc6/setup.sh
[username@ui3 ~]$ gcc --version
gcc (GCC) 4.9.3 Copyright (C) 2015 Free Software Foundation, Inc. ...