1. download gcc-5.3 source code:
curl ftp://ftp.gnu.org/pub/gnu/gcc/gcc-5.3.0/gcc-5.3.0.tar.bz2 -O
or:
ftp://ftp.gnu.org/pub/gnu/gcc/gcc-5.3.0/gcc-5.3.0.tar.bz2.sig
2. untar it:
tar xvfj gcc-5.3.0.tar.bz2
cd gcc-5.3.0
3. download prerequisites
./contrib/download_prerequisites
4. Compile gcc-5.3
unset CPLUS_INCLUDE_PATH LIBRARY_PATH
./configure --enable-threads=posix --disable-checking --disable-multilib --enable-languages=c,c++ --prefix=/opt/rh/devtoolset-6/root/usr --mandir=/opt/rh/devtoolset-6/root/usr/share/man --infodir=/opt/rh/devtoolset-6/root/usr/share/info
make clean && make -j3
make install
5. Add confige in bash_profile
1). first open ~/.bash_profile
2). append below to it:
scl enable devtoolset-6 bash
Done.
