我正在尝试这样做
$ sudo yum install gnome-tweak-tool
我立即得到了这样的答复：
Loaded plugins: langpacks, presto, refresh-packagekit
http://yum.postgresql.org/9.1/redhat/rhel-18-x86_64/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found : http://yum.postgresql.org/9.1/redhat/rhel-18-x86_64/repodata/repomd.xml
Trying other mirror.
Error: failure: repodata/repomd.xml from pgdg91: [Errno 256] No more mirrors to try.
http://yum.postgresql.org/9.1/redhat/rhel-18-x86_64/repodata/repomd.xml: [Errno 14] HTTP Error 404 - Not Found : http://yum.postgresql.org/9.1/redhat/rhel-18-x86_64/repodata/repomd.xml
我想我搞乱了 yum repo，有什么办法可以解决这个问题吗？