Modifying Runlevels on Linux

We, along with our team, are in charge of managing the various Linux systems at our company. In order to comply with the standards throughout the organization, we have been tasked with modifying the run levels for our CentOS and Ubuntu hosts.

For the CentOS hosts, we need to disable the crond service for runlevels 2 and 4. We also must enable the httpd service for runlevels 3 and 5. Then, we need to modify the initialization script for the postfix service with the following changes:

• The service should only be enabled for runlevel 3.
• The start priority should be 78.
• The kill priority should be 35.

Once the script has been updated, the service needs to be deleted and added again to apply the changes.

For the Ubuntu hosts, remove the SysV init links for the nginx service. Then, enable the lighttpd service for runlevels 2 and 5. Finally, add the default SysV init links for the Bluetooth service.

Note: All tasks should be performed as the root user. Also, if a service is not installed as expected (i.e., httpd), this means that the lab has not completed initializing. You may need to wait a couple minutes until the initialization is complete.