https://wiki.jenkins-ci.org/display/JENKINS/Installing+Jenkins+on+Red+Hat+distributions

Step 1:
sudo yum install wget -y

Step 2:
sudo wget -O /etc/yum.repos.d/jenkins.repo http://pkg.jenkins-ci.org/redhat/jenkins.repo

Step 3:
sudo rpm --import https://jenkins-ci.org/redhat/jenkins-ci.org.key

Step 4:
sudo yum install jenkins

Step 5:
sudo yum install java

Step 6:
sudo service jenkins start 

Step 7:
sudo chkconfig jenkins on

Step 8:
Go to AWS RHEL Instance and find the security wizard used --> Go to Security Groups -->select the security wizard -->Actions --> Edit inbound Rules -->Type --> ALL TCP --> Save

Step 9:
Find the public IP Address of your instance

Step 10: 
Enter public ip followed by Port 8080. Ex: http://35.160.91.135:8080

Step 11:
Initial jenkins screen shows admin password location --> Copy that location

Step 12: 
sudo cat "/Admin/Password/Location". Ex: sudo cat /var/lib/jenkins/secrets/initialAdminPassword

Step 13:
Install suggested plugins and create user profile



SCRIPT
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Follow the instructions below to install jenkins on RHEL/CentOs 

Hint: To run multiple commands in a sequence one after the other, seperate commands with semicolon ";".

sudo yum install wget -y;sudo wget -O /etc/yum.repos.d/jenkins.repo http://pkg.jenkins-ci.org/redhat/jenkins.repo;sudo rpm --import https://jenkins-ci.org/redhat/jenkins-ci.org.key;sudo yum install jenkins;sudo yum install java;sudo service jenkins start;sudo chkconfig jenkins on



Jenkins Build fail 
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add this under git ref spec
+refs/heads/master:refs/remotes/origin/master