How to check jenkins is installed in centos or not?

Go to your /var/lib/jenkins/ there will be a file called config.xml

View that file cat config.xml and there should be a xml entry called:

<version>YourVersionNumber</version>

Or on the Jenkins home screen when it is running click the About button and you will see the version number there.

The generic start up for Jenkins is:

java -jar jenkins.war

Which can be found here

As you've installed it through yum, this command should do

sudo service jenkins status

This one also (it's the same):

sudo /etc/init.d/jenkins status

If they return a missing file error, e.g. something like

env: /etc/init.d/jenkins: No such file or directory

, it's not installed - at least not through a package manager.