Runit

Runit is a UNIX init system with service supervision — a replacement for sysvinit and other init schemes. It’s small, fast, and follows the Unix philosophy of doing one thing well. Written by Gerrit Pape, it’s been around since the early 2000s and is battle-tested.

Philosophy

Runit is built on the same ideas as daemontools (by DJ Bernstein): each service gets its own supervision directory with a run script, and a supervisor process (runsv) keeps it alive. If the service crashes, it’s automatically restarted. No complex service files, no binary logs, no centralized daemon — just scripts and processes.

Who uses it?

Void Linux — its default init system
Artix Linux — available as an alternative
AntiX — defaults to runit
Embedded systems, containers, minimal installs

How it works

Runit boots in three stages:

Stage 1 (/etc/runit/1)    → One-time initialization (filesystems, udev, etc.)
Stage 2 (/etc/runit/2)    → runsvdir starts, supervises all services
Stage 3 (/etc/runit/3)    → Shutdown (kill processes, unmount, halt)

Services live in /etc/sv/ and are enabled by symlinking into /run/runit/service (or /etc/runit/runsvdir/default/).

Key concepts

Concept	What it means
Service directories	Each service is a directory with an executable `run` script
`runsv`	Supervises one service, restarts it if it crashes
`runsvdir`	Starts/stops supervisors for a collection of services
`sv`	Main control tool — start, stop, restart, status
Runlevels	Directories under `/etc/runit/runsvdir/` (default, single, etc.)
Logging	Optional — add a `log/` subdirectory with its own `run` script

Basic commands

# Start a service
sv up sshd

# Stop a service
sv down sshd

# Restart a service
sv restart sshd

# Check status
sv status sshd

# Enable at boot (create symlink)
ln -s /etc/sv/sshd /etc/runit/runsvdir/default/

# Disable at boot (remove symlink)
rm /etc/runit/runsvdir/default/sshd

Example service

/etc/sv/sshd/run:

#!/bin/sh
exec /usr/bin/sshd -D

That’s it. No config parsing, no dependency declarations, no unit files. If the script exits, runsv restarts it. If you want logging, add log/run:

/etc/sv/sshd/log/run:

#!/bin/sh
exec svlogd -tt /var/log/sshd

Comparison with OpenRC

	OpenRC	Runit
Service format	Shell scripts with `start()`/`stop()`	Executable `run` scripts
Dependencies	Manual (`need`/`use`)	None (automatic via sv)
Supervision	No built-in	Yes — auto-restart on crash
Logging	syslog or separate	Built-in per-service logging
Boot speed	Fast	Very fast
Complexity	Low	Low

Should you use it?

Pick Runit if:

You want the simplest possible supervision system
You like the daemontools model (one script per service)
You want auto-restart on crash
You’re coming from Void Linux and want the same experience

Stick with OpenRC if:

You need dependency management
You prefer shell scripts with start/stop/status functions
You want something more mainstream