Steps for RHEL5 to OLE5 Migration.

[root@sankar-devops ~]#  cat /etc/redhat-release
Red Hat Enterprise Linux Server release 5.10 (Tikanga)

[root@sankar-devops ~]# cat /etc/issue
Red Hat Enterprise Linux Server release 5.10 (Tikanga)
Kernel \r on an \m


[root@sankar-devops ~]#
[root@sankar-devops ~]# yum -y remove rhn-client-tools yum-rhn-plugin up2date subscription-manager
Loaded plugins: rhnplugin, security
There was an error communicating with RHN.
RHN Satellite or RHN Classic support will be disabled.

Setting up Remove Process
No Match for argument: up2date
No Match for argument: subscription-manager
Resolving Dependencies
--> Running transaction check
---> Package rhn-client-tools.noarch 0:0.4.20-77.el5 set to be erased
--> Processing Dependency: rhn-client-tools = 0.4.20-77.el5 for package: rhn-setup
--> Processing Dependency: rhn-client-tools = 0.4.20-77.el5 for package: rhn-check
---> Package yum-rhn-plugin.noarch 0:0.5.4-26.el5 set to be erased
--> Running transaction check
---> Package rhn-check.noarch 0:0.4.20-77.el5 set to be erased
--> Processing Dependency: rhn-check >= 0.0.8 for package: rhnsd
---> Package rhn-setup.noarch 0:0.4.20-77.el5 set to be erased
--> Running transaction check
---> Package rhnsd.x86_64 0:4.7.0-10.el5 set to be erased
--> Finished Dependency Resolution

Dependencies Resolved

======================================================================================================================================
 Package                             Arch                      Version                             Repository                    Size
======================================================================================================================================
Removing:
 rhn-client-tools                    noarch                    0.4.20-77.el5                       installed                     0.0
 yum-rhn-plugin                      noarch                    0.5.4-26.el5                        installed                    182 k
Removing for dependencies:
 rhn-check                           noarch                    0.4.20-77.el5                       installed                     0.0
 rhn-setup                           noarch                    0.4.20-77.el5                       installed                     0.0
 rhnsd                               x86_64                    4.7.0-10.el5                        installed                     72 k

Transaction Summary
======================================================================================================================================
Remove        5 Package(s)
Reinstall     0 Package(s)
Downgrade     0 Package(s)

Downloading Packages:
Running rpm_check_debug
Running Transaction Test
Finished Transaction Test
Transaction Test Succeeded
Running Transaction
  Erasing        : rhn-setup                                                                                                      1/5
  Erasing        : rhnsd                                                                                                          2/5
  Erasing        : rhn-check                                                                                                      3/5
  Erasing        : rhn-client-tools                                                                                               4/5
warning: /etc/sysconfig/rhn/up2date saved as /etc/sysconfig/rhn/up2date.rpmsave
  Erasing        : yum-rhn-plugin                                                                                                 5/5
warning: /etc/yum/pluginconf.d/rhnplugin.conf saved as /etc/yum/pluginconf.d/rhnplugin.conf.rpmsave

Removed:
  rhn-client-tools.noarch 0:0.4.20-77.el5                             yum-rhn-plugin.noarch 0:0.5.4-26.el5                         

Dependency Removed:
  rhn-check.noarch 0:0.4.20-77.el5              rhn-setup.noarch 0:0.4.20-77.el5              rhnsd.x86_64 0:4.7.0-10.el5           

Complete!
[root@sankar-devops ~]#

[root@sankar-devops ~]# cd /etc/yum.repos.d

[root@sankar-devops yum.repos.d]#rm -rf *

[root@sankar-devops yum.repos.d]# ll
total 0
[root@sankar-devops yum.repos.d]# wget http://yum.oracle.com/public-yum-el5.repo
--2018-05-09 00:44:08--  http://yum.oracle.com/public-yum-el5.repo
Resolving yum.oracle.com... 184.25.162.159
Connecting to yum.oracle.com|184.25.162.159|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 4886 (4.8K) [text/plain]
Saving to: `public-yum-el5.repo'

100%[============================================================================================>] 4,886       --.-K/s   in 0s   

2018-05-09 00:44:09 (12.5 MB/s) - `public-yum-el5.repo' saved [4886/4886]

[root@sankar-devops yum.repos.d]# wget https://linux-update.oracle.com/rpms/ULN-CA-CERT.sha2 -O /usr/share/rhn/ULN-CA-CERT
--2018-05-09 00:44:16--  https://linux-update.oracle.com/rpms/ULN-CA-CERT.sha2
wget http://public-yum.oracle.com/RPM-GPG-KEY-oracle-el5 -O /etc/pki/rpm-gpg/RPM-GPG-KEY-oracleResolving linux-update.oracle.com... 137.254.56.42
Connecting to linux-update.oracle.com|137.254.56.42|:443... connected.
HTTP request sent, awaiting response...

[root@sankar-devops yum.repos.d]# ll
total 8
-rw-r--r-- 1 root root 4886 Feb 12 20:32 public-yum-el5.repo

[root@sankar-devops yum.repos.d]# wget https://linux-update.oracle.com/rpms/ULN-CA-CERT.sha2 -O /usr/share/rhn/ULN-CA-CERT
--2018-05-09 00:47:43--  https://linux-update.oracle.com/rpms/ULN-CA-CERT.sha2
Resolving linux-update.oracle.com... 137.254.56.42
Connecting to linux-update.oracle.com|137.254.56.42|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 7727 (7.5K) [text/plain]
Saving to: `/usr/share/rhn/ULN-CA-CERT'

100%[============================================================================================>] 7,727       11.4K/s   in 0.7s 

2018-05-09 00:49:50 (11.4 KB/s) - `/usr/share/rhn/ULN-CA-CERT' saved [7727/7727]

[root@sankar-devops yum.repos.d]# wget http://public-yum.oracle.com/RPM-GPG-KEY-oracle-el5 -O /etc/pki/rpm-gpg/RPM-GPG-KEY-oracle
--2018-05-09 00:52:11--  http://public-yum.oracle.com/RPM-GPG-KEY-oracle-el5
Resolving public-yum.oracle.com... 184.84.98.170
Connecting to public-yum.oracle.com|184.84.98.170|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1397 (1.4K) [text/plain]
Saving to: `/etc/pki/rpm-gpg/RPM-GPG-KEY-oracle'

100%[============================================================================================>] 1,397       --.-K/s   in 0s   

2018-05-09 00:52:12 (88.8 MB/s) - `/etc/pki/rpm-gpg/RPM-GPG-KEY-oracle' saved [1397/1397]

[root@sankar-devops yum.repos.d]# gpg --quiet --with-fingerprint /etc/pki/rpm-gpg/RPM-GPG-KEY-oracle

pub  1024D/1E5E0159 2007-05-18 Oracle OSS group (Open Source Software group) <build@oss.oracle.com>
      Key fingerprint = 99FD 2766 28EE DECB 5E5A  F5F8 66CE D3DE 1E5E 0159
sub  1024g/D303656F 2007-05-18 [expires: 2015-05-16]

[root@sankar-devops yum.repos.d]# yum -y upgrade yum* enterprise-release-notes oracle-logos rpm* redhat* system-config*
Loaded plugins: security
el5_latest                                                                                                     | 1.4 kB     00:00   
el5_latest/primary                                                                                             |  29 MB     05:29   
el5_latest                                                                                                                15734/15734
ol5_UEK_latest                                                                                                 | 1.2 kB     00:00

[root@sankar-devops yum.repos.d]# yum update

[root@sankar-devops yum.repos.d]# cat /etc/issue

Oracle Linux Server release 5.11

Kernel \r on an \m