check_mk

Check a host manually

$ cmk -nv [hostname]

$ cmk -I [hostname]

$ cmk -I

$ cmk -O

$ cmk -d [hostname]

$ cmk --list-hosts

$ cmk -R

cmk [options] [hostname]

Checkmk (formerly Check_MK) is a comprehensive IT monitoring solution built on Nagios monitoring core concepts. The cmk command is the central CLI tool for managing hosts, services, and configuration.
The system uses agents installed on monitored hosts that collect metrics and status information. The cmk command processes this data, discovers available services, performs checks, and manages the configuration.
Discovery (cmk -I) scans hosts for monitorable services. Configuration changes require activation with cmk -O or cmk -R. The tool supports distributed monitoring, agent bakery for deployment, and extensive plugin architecture.

-I, --discover

Discover new services on hosts.

Remove vanished services and discover new ones.

Check host and show verbose output.

Dump agent output from host.

Reload configuration without restart.

Restart monitoring core.

List all configured hosts.

List all available check plugins.

Show Checkmk directory paths.

Manage extension packages (install, remove, list).

Enable debug output.

Changes to configuration must be activated before taking effect. The commercial editions (CEE, CME) have additional features not in Raw Edition. Large-scale discoveries can be resource-intensive. Agent-based monitoring requires agents deployed on target hosts.

Check_MK was created by Mathias Kettner in 2008 as an extension to Nagios to simplify configuration and improve performance. It evolved from a plugin to a complete monitoring solution. In 2019, the project rebranded to Checkmk and tribe29 GmbH (now Checkmk GmbH) was founded. The Raw Edition remains open source while commercial editions add enterprise features.

nagios(8), icinga2(8), prometheus(1), zabbix(1)