Runit

Runit is a small, cross‑platform init scheme and service supervisor for Unix‑like operating systems. It aims to be simple, fast, and reliable, providing robust process supervision with a minimal footprint and limited configuration.

Runit consists of a few core programs and a lightweight workflow. The supervisor runs as PID 1 in an init role or can be used as a supervising daemon in other contexts. The main tools are runsvdir, which supervises all services, and runsv, which supervises an individual service. Helper utilities such as chpst are included to set users, environments, and chroots for supervised processes. Services are defined by directories, commonly under /service, each containing a run script that starts the service. If a service has logging, it can include a log directory with its own run script, and runit will start a separate logger process for that service.

Defining and managing a service is straightforward. Create a directory /service/name with a runnable /service/name/run that launches the service. Optional logging is configured by providing /service/name/log/run. The supervisor starts runsv for each service and will automatically restart a service if it exits unexpectedly. Control utilities such as sv allow administrators to start, stop, restart, or query the status of services.

Runit is designed for portability and is used as the default init system in several distributions, including Void Linux, among others. It emphasizes predictable boot times, parallel startup, clean shutdown, and a compact codebase. Licensing is under a BSD-style license.

See also: relation to other init and supervision systems, such as daemontools, and its role as an alternative to more feature-rich init systems.