When you start Jenkins, the configuration is created along with the initial default administrator account.
You can use the default admin username and password to access the Jenkins UI.
The Jenkins default password is stored in the
$JENKINS_HOME/secrets/initialAdminPassword file (the exact location of the Jenkins default password is presented in the Jenkins console log).
Default Jenkins Password:
The Jenkins default username is admin.
The Jenkins default password :
$JENKINS_HOME/secrets/initialAdmin
Password file on the server, that is usually located at:
/var/lib/jenkins/secrets/initialAdminPassword
Default Username File with default Password
admin /var/lib/jenkins/secrets/initialAdminPassword