Problem scenario
You want to see options for the yum-config-manager command. How do you find which repositories can be enabled for a Red Hat Enterprise Linux server?
Solution
Run this command: sudo yum repolist all
With the output on the left, you will need what is left of the "/" (forward slash) if one appears in a command like this: sudo yum-config-manager --enable rhui-REGION-rhel-server-rhscl
Let's say you see this output below from the sudo yum repolist all command:
rhui-REGION-rhel-server-source-supplementary/7Server/x86_64 Red Hat Enterprise Linux Server 7 Supplementary (SRPMs) disabled
To use this output, as a single example, you will want only the rhui-REGION-rhel-server-source-supplementary as the argument to the "enable" flag option with your yum-config-manager command. The format of the output gives more details that would not necessarily be used in subsequent commands.
The rhui-REGION-rhel-server-extras is a common package to want or need to enable.