follow this step to install freesurfer .
first
untar the file ‘freesurfer-Linux-centos64…tar.gz’
than copy to the directory you want .
sudo cp -r /home/clancy/Downloads/freesurfer-Linux-centos64.../freesurfer /usr/local/
than set the environment
sudo gedit /etc/bash.bshrc
export FREESURFER_HOME=/usr/local/freesurfer
source $FREESURFER_HOME/SetUpFreeSurfer.sh
than open a new terminal ,you’ll find the version infomation and other information, it means you have finished the install successful.