Yum not installing 7zip
An issue I had with yum not installing 7zip on a CentOS machine
Earlier I had an issue with yum not installing 7zip (or indeed anything) on a CentOS machine. I was trying to run;
sudo yum install p7zip
The fix (provided by @braziel) was to run the following 4 lines of code, which seem to update yum effectively.
rpm --import http://apt.sw.be/RPM-GPG-KEY.dag.txt
rpm -K rpmforge-release-0.5.2-2.el5.rf.*.rpm
rpm -i rpmforge-release-0.5.2-2.el5.rf.*.rpm