OpenRC

OpenRC is a dependency-based init system and service manager for Unix-like operating systems. It originated in Gentoo Linux and was developed by Roy Marples to provide a lightweight, portable, and fast alternative to monolithic init daemons. OpenRC emphasizes correct startup and shutdown ordering through explicit service dependencies while enabling parallel startup where possible.

The core concept of OpenRC is the use of service scripts and runlevels. System services are defined by scripts located in /etc/init.d, and their startup order is determined by dependencies declared within those scripts using keywords such as need, after, before, and use. Runlevels control which services are active at different stages of boot or shutdown, with common levels including boot, default, and shutdown. OpenRC provides a small toolset for managing these elements: rc-update to add or remove services from runlevels, rc-status to report service states, and rc-service to start, stop, restart, or reload a service.

OpenRC is designed to be portable and lightweight. It has been adopted by several distributions beyond Gentoo, most notably Alpine Linux and Artix Linux, where it serves as an alternative to other init systems. The project aims to minimize complexity by avoiding a single monolithic daemon and instead coordinating a set of scripts and a small coordinating program to manage services and their dependencies.

In usage, OpenRC offers a straightforward model for administrators who prefer explicit dependency-based control over service management. While it provides many of the same lifecycle operations as other init systems, its design emphasizes clarity, modularity, and parallelism without relying on a central daemon.