At present time Devtoolset-5 (and earlier) cannot be istalled from Software Collection Repository (centos-release-scl) using yum (only Devtoolset-6 and 7 are available). Nevertheless this collection can be downloaded as a list of rpm-packages. Is it possible to enable such EOL collections for yum, or maybe there is another way to install them correctly?
You can install the obsolete devtoolset-3 in this way:
sudo yum --obsolete install devtoolset-3
There was no DTS 5 release. It was skipped to align the DTS version with the GCC major release, once GCC switched to a yearly increasing version number.
DTS versions 3 and 4 are available from the centos-release-scl repository.
While Devtoolset-3 and 4 are located on the site here: http://mirror.centos.org/centos/6/sclo/x86_64/rh, yum will not be able to find them as they were not included in the repodata on the site. These were probably excluded because they are EOL, and have dependency bugs (Bug 1410152). Try using the older Devtoolset-3 packages here, which do not have the dependency issues: https://copr.fedorainfracloud.org/coprs/rhscl/devtoolset-3/
If you really want the packages from the centos.org site, I went with wget to download all the RPMs, then recreated a local yum repo. However, you'll see the dependency issues and yum install devtoolset-3 will fail.
[user1@localhost ~]$ wget -r -p -e robots=off --directory-prefix="/mnt/local-devtoolset3-repo" --recursive --no-clobber --no-parent http://mirror.centos.org/centos/6/sclo/x86_64/rh/devtoolset-3/
[user1@localhost ~]$ sudo yum install createrepo
[user1@localhost ~]$ cd /mnt/local-devtoolset3-repo
[user1@localhost ~]$ createrepo --database .
来源：https://stackoverflow.com/questions/51674966/install-obsolete-devtoolset-collection-for-centos