Check_MK is a complex addon for Nagios/Icinga and consists of three subprojects. The check and inventory system Check_MK is a general purpose Nagios plugin for retrieving data. It adopts a new approach for collecting data and obsoletes NRPE, check_by_ssh, NSClient, and check_snmp. It features a significant reduction of CPU use on the Nagios host and automatic inventory of items to be checked, and is especially useful with larger Nagios installations. "MK Livestatus" gives immediate and fast access to live and historic Nagios status data. It's a supported backend for many addons including NagVis, NagiosBP, and Thruk. "Check_MK Multisite" is a feature complete replacement for the Nagios GUI, and uses MK Livestatus as a backend. It is very fast, and supports efficient distributed monitoring.
selector is a command line utility for dynamic string selection. As you type a list of substrings separated by ";" or a regexp, the display is updated in real time to show only the matching lines. The main usage of selector is as an efficient search in the shell command history. With the correct option, it will inject the selected line into the terminal input buffer, allowing the user to edit the line and execute it as a standard command.