This an Easy and Step-by-Step Guide to Install and Quickly Getting-Started the Oracle 11g R2 Database on a Red Hat Enterprise Linux 6.x System.
To have a Nice Journey through this WoWtUt Relax and Take the Time of Reading, Understanding and Executing Carefully the Instructions Contained here.
To the Article Bottom you Find Links to Oracle 11g Database Detailed Troubleshooting Guides.
Open a Terminal Window
(Press “Enter” to Execute Commands)
su
If Got “User is Not in Sudoers file” then see: How to Enable sudo
Check you hostname and IP is on /etc/hosts.
Get your hostname:
hostname
Get your IP:
/sbin/ifconfig
You will Find your Ip under the Output “lo” Section.
Check if Hostname and IP are already inserted into the Enabled Hosts File.
cat /etc/hosts
If It’s Not Present then Insert it!
nano /etc/hosts
Insert:
Example: ‘127.0.0.1 localhost.localdomain localhost’
Ctrl+Shift+v to Paste Content on nano
Ctrl+x to Save and Exit from nano Editor :)
Add you Host IP to the List of Hosts Granted of Connection with the X Server
xhost +yourIP
Example: #xhost +127.0.0.1
If you Do Not Dispose of RHEL Subscription.
Install dependencies
sudo yum install binutils glibc compat-libstdc++-33 glibc-common
glibc-devel glibc-headers elfutils-libelf elfutils-libelf-devel
elfutils gcc gcc-c++ ksh libaio libaio-devel libgcc libstdc++-devel
make numactl-devel sysstat mksh
Add Groups and User
groupadd -g 502 oinstall
groupadd -g 503 dba
groupadd -g 504 oper
groupadd -g 505 asmadmin
useradd -u 502 -g oinstall -G dba,asmadmin,oper -s /bin/bash -m oracle
passwd oracle
Take Note of the oracle User Pass :)
Create the directories where Oracle will be installed and give right ownership and permission
mkdir -p /u01/app/oracle/product/11.2.0/
chown -R oracle:oinstall /u01
chmod -R 775 /u01
Set Kernel’s Parameters
nano /etc/sysctl.conf
Then hit Ctrl+x to Save and Exit from nano EditorAdd or amend the following lines in the /etc/sysctl.conf file.
#### Oracle 11g Kernel Parameters ####
fs.suid_dumpable = 1
fs.aio-max-nr = 1048576
fs.file-max = 6815744
kernel.shmall = 818227
kernel.shmmax = 4189323264
kernel.shmmni = 4096
# semaphores: semmsl, semmns, semopm, semmni
kernel.sem = 250 32000 100 128
net.ipv4.ip_local_port_range = 9000 65500
net.core.rmem_default=262144
net.core.rmem_max=4194304
net.core.wmem_default=262144
net.core.wmem_max=1048576
Comment out these lines below than give an error
#net.bridge.bridge-nf-call-ip6tables = 0
#net.bridge.bridge-nf-call-iptables = 0
#net.bridge.bridge-nf-call-arptables = 0
nano /etc/security/limits.conf
Add the following lines to the /etc/security/limits.conf file.
#### oracle User Settings 4 Oracle 11g ####
oracle soft nproc 2047
oracle hard nproc 16384
oracle soft nofile 1024
oracle hard nofile 65536
oracle soft stack 10240
nano /etc/selinux/config
Disable Secure Linux by editing the /etc/selinux/config file, making sure the SELINUX flag is set as follows.
SELINUX=disabled
Run the following command to Load the New Kernel Parameters.
/sbin/sysctl -p
Unzip the Oracle 11g Database, Set oracle as Owner and Move it into the oracle’s Home
cd </path/2>
unzip linux_11gR2_database_1of2.zip
unzip linux_11gR2_database_2of2.zip
chown -R oracle:oinstall database
mv database /home/oracle
su oracle
Edit .bashrc file
nano ~/.bashrc
Insert:
# Oracle Settings
TMP=/tmp; export TMP
TMPDIR=$TMP; export TMPDIR
ORACLE_HOSTNAME=myHOSTNAME; export ORACLE_HOSTNAME
ORACLE_UNQNAME=DB11G; export ORACLE_UNQNAME
ORACLE_BASE=/u01/app/oracle; export ORACLE_BASE
ORACLE_HOME=$ORACLE_BASE/product/11.2.0/dbhome_1; export ORACLE_HOME
ORACLE_SID=dbSID; export ORACLE_SID
PATH=/usr/sbin:$PATH; export PATH
PATH=$ORACLE_HOME/bin:$PATH; export PATH
LD_LIBRARY_PATH=$ORACLE_HOME/lib:/lib:/usr/lib; export LD_LIBRARY_PATH
CLASSPATH=$ORACLE_HOME/jlib:$ORACLE_HOME/rdbms/jlib; export CLASSPATH
Replace [HOSTNAME] with IP and [DBSID] with SID Name
In this Example Respectively:
HOSTNAME = 127.0.0.1
DBSID = SID
Load New .bashrc Settings.
bash
Latest and Optional to Add Cross-Shell Compatibility edit also oracle’s .bashrc.
nano ~/.bashrc
Add as Latest Entry the Line.
bash
cd /home/oracle/database
./runInstaller
If you Get: “Check if the DISPLAY variable is set. Failed”. Look Link Below.
Link2+ Oracle 11g Database Troubleshooting.
On the first screen If you Do Not Dispose of an Oracle Subscription Just Leave Blank eMail and Un-Check the Demand of Security Update Support then Click on Next
Then Confirm on Warning and Follow.
On “Select Installation Option” Select “Install database software only” and Click on Next
On Step 3 Leave Default “Single instance database installation” and Click on Next
On Step 4 Select your Language and Click on Next
On Step 5 Leave Default Enterprise Edition and Click on Next
On “Installation Location” Set All As Here Below and Click on Next
Oracle Base: /u01/app/oracle
Software Location: /u01/app/oracle/product/11.2.0/dbhome_1
.
These are the Same Settings Inserted into the .bashrc File…
On “Create Inventory” if you Setup the Path on .bashrc Like Here Leave Default and Click on Next
On “Operating System Groups” if you Setup the Path on .bashrc Like Here Leave Default and Click on Next
On “Prerequisite Checks” you will Get Easily a “Warning Message” about some Missing Requirements.
Just Check: “Ignore All” and Follow Up with Installation…
On the “Summary” Click on “Save Response File” to Take Note of Settings and then Click on Finish
The Installation Product Procedure should Start… Wait Until Successful Achievement. 
Right Before the End of Process a Pop-Up Window will Show the Path to Two Configuration Scripts you Need to Execute on Terminal!
Latest Oracle Should Confirm you of a Successful Installation End.) 
How to Create and Run an Oracle 11g Listener:
https://127.0.0.1:1158/em
And you can Login with:
Username: SYS
Password: oracleDatabasePassword
From the Drop-down below Select >> Connect as SYSDBA
You Should be able to Access the Database by the Enterprise Manager!
Enjoy this “Step by Step” Clear Installation and Getting Started…
Good Luck! :)