CentOS 6 gcc 버전 업데이트

$ yum install centos-release-scl-rh centos-release-scl
$ yum check-update
$ yum install devtoolset-7-gcc-c++
$ source /opt/rh/devtoolset-7/enable
$ gcc --version
gcc (GCC) 7.3.1 20180303 (Red Hat 7.3.1-5)
Copyright (C) 2017 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

아래도 가능..

yum install devtoolset-7-gcc-c++ (GCC 7.3.1)
yum install devtoolset-8-gcc-c++ (GCC 8.3.1)
yum install devtoolset-9-gcc-c++ (GCC 9.1.1)

아래와 같이 devtoolset-7-gcc-c++ 을 enable..

$ vim /etc/profile.d/enabledevtoolset-7.sh
#!/bin/bash
source /opt/rh/devtoolset-7/enable