centos7 使用SCL（SoftwareCollections）安装 gcc8

$ sudo yum install centos-release-scl
$ sudo yum install scl-utils

$ # gcc gdb valgrind systemtap
$ sudo yum install devtoolset-8

$ scl --list
devtoolset-8

$ scl enable devtoolset-8 bash

$ # bashrc
$ # source /opt/rh/devtoolset-8/enable

$ gcc --version
gcc (GCC) 8.2.1 20180905 (Red Hat 8.2.1-3)
Copyright (C) 2018 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.