Q. By accident my yum command was deleted under Red Hat Enterprise Linux version 5.x. Now I'm not able to download and update system using RHN. How do I fix this issue without reinstalling RHEL again?
A. You can try any one of the following solutions to restore yum:
(a) Copy yum command (/usr/bin/yum) from other working system (same version and architecture) using ssh / scp command.
(b) Download yum rpm itself from RHN. First, log into RHN. Select the "Channels" tab then select the "Red Hat Enterprise Linux" channel for your system in the channel name table. You can search RPM and then select "Package" link. Once downloaded just run rpm command over yum command.
# rpm -ivh --force rpm*
(c) Download yum source rpm from public Red Hat ftp server and rebuild yum rpm:
# wget http://ftp.redhat.com/pub/redhat/linux/enterprise/5Server/en/os/SRPMS/yum-3.0.1-5.el5.src.rpm
# rpm -ivh yum-3.0.1-5.el5.src.rpm
# cd /usr/src/redhat/SPECS
# rpmbuild -bb yum.spec
# rpm -ivh --force /usr/src/redhat/RPMS/noarch/yum-3.0.1-5.noarch.rpm
# yum --version
(d) Grab yum rpm from one of the CentOS mirror and just install it.
(e) Copy yum binary from your backup tape device.
(f) Copy yum RPM from updated media CD / DVD and install the same using rpm command.