Use modern compilers in RHEL

Often we need a more modern compiler than is included in Red Hat / CentOS for HPC systems. Once an admin sets up GCC Toolset they can be loaded by any user thereafter.

To install and use a recent GFortran version, have the system admin do like:

yum install gcc-toolset-12-gcc-gfortran

Thereafter, users without sudo use the new Gfortran version for that Terminal session only by:

scl enable gcc-toolset-12 bash

Prior to CentOS / RHEL 8, this was known as Developer Toolset devtoolset.