Question: Helping out someone who inherited his environment. He wants to disable some repositories. This is an anonymized output of his `yum repolist`:

```
luke@server1 $ sudo yum repolist
Loaded plugins: rhnplugin, security
This system is receiving updates from RHN Classic or RHN Satellite.
repo id                        repo name                                                 status
acme-rhel-x86-64-server-5      ACME Packages (v.5 for 64-bit)                                 1
epel                           Extra Packages for Enterprise Linux 5 - x86_64             7,745
rhel-x86_64-server-5           Red Hat Enterprise Linux (v. 5 for 64-bit x86_64)         16,133
rhn-tools-rhel-x86_64-server-5 Red Hat Network Tools for RHEL Server (v.5 64-bit x86_64)    564
repolist: 24,443

```

However, doing the following yields no results:

```
luke@server1 $ grep -ri acme /etc/yum.repos.d /etc/yum/pluginconf.d

```

Answer: 
Most likely it is using the rhnplugin to access "RHN Classic." To disable a repository (unsubscribe from a channel) you use the [`rhn-channel`](https://access.redhat.com/solutions/57504)command or the web interface at <http://rhn.redhat.com/>
While `.repo` files are usually placed in `/etc/yum.repos.d` you can specify a different directory by using `reposdir=xxx` in`/etc/yum.conf`.