Nagios is a series of free, open source system monitoring applications designed to monitor aspects of host and network services on computer servers. Nagios has the ability to detect and alert users when problems occur in network and host services. Ubuntu Server is based on the Debian Linux operating system, and is compatible with a wide range of server software, including the Nagios software packages.
Open the Terminal application in Ubuntu Server or go to the command line interface. Ubuntu Server is a versatile operating system, and each installation can be visually different. Installations with a graphic user interface can find the Terminal application in the main menu. Versions that only use a command line interface can enter all commands there at the prompt.
Type "sudo apt-get remove nagios-agent," at the command prompt. Press the "Enter" key and enter your root password at the prompt. Press "Enter" again to remove the main Nagios package. "Apt-get" is a command line tool used in Ubuntu for adding, removing and updating software packages.
Type "sudo apt-get --purge autoremove nagios-agent" to remove any extra files linked to the Nagios application. The Purge command removes all configuration files and logs linked to the program, while the Autoremove command removes any dependencies or extra software needed to run an application downloaded by Nagios when it was originally installed.
Type "apt-get update" and press "Enter." This will update the lists of software available to the computer. Type "apt-get --check upgrade" and press "Enter" to upgrade any software packages that have available updates, as well as check that all the installed applications have the appropriate dependencies.