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

When to use Runit

Runit is suitable for users who want a minimal supervision-based init with automatic service restart on crash. Its service model (one executable run script per service) is straightforward and requires no dependency declarations.

Users coming from Void Linux will find Runit familiar. For users who need dependency management between services, OpenRC or Dinit may be more appropriate.

Learn more