The script will install GCC 5.4.0 on your CentOS 7 system, make sure you have root right. See https://jdhao.github.io/2017/09/04/install-gcc-newer-version-on-centos/ for more details.

gcc-5.4.0-install.sh

echo "Downloading gcc source files..."
curl https://ftp.gnu.org/gnu/gcc/gcc-5.4.0/gcc-5.4.0.tar.bz2 -O

echo "extracting files..."
tar xvfj gcc-5.4.0.tar.bz2

echo "Installing dependencies..."
yum -y install gmp-devel mpfr-devel libmpc-devel

echo "Configure and install..."
mkdir gcc-5.4.0-build
cd gcc-5.4.0-build
../gcc-5.4.0/configure --enable-languages=c,c++ --disable-multilib
make -j$(nproc) && make install

In my case, this script is giving error:

configure: error: error verifying int64_t uses long long 
make[2]: *** [configure-stage1-gcc] Error 1

I solved this by installing gcc-c++

yum install gcc-c++ -y

@jdhao thank you for posting this...it was very helpful! Now I need to downgrade back to gcc 4.8, but I am unable to. Any advice on how to do so?

@miamartin8, I think you can just install gcc 4.8. Multitiple gcc installation is fine, you can just add --prefix /gcc/install/path to indicate where you want to install it instead of the default location. After installation, you can manipulate your $PATH variable to indicate which gcc you want to use.

Ref: https://askubuntu.com/questions/891835/what-does-prefix-do-exactly-when-used-in-configure

too dependent on yum can be problematic since it requires sudo.

@knasim, yeah, that is true. If you do not have sudo rights, you also have to compile the dependencies from source.
At the time of writing this script, I had sudo rights, so I just installed the dependency via yum.

@jdhao
do I need to add this in my profile?

export PATH=/usr/local/bin:$PATH
export LD_LIBRARY_PATH=/usr/local/lib64:$LD_LIBRARY_PATH

or optional?