void-linux/runit

How void-linux/runit works

runit is a Unix service supervision and logging suite. Its principal workflow is system startup into a service-directory supervisor, which launches and monitors service processes; operators issue control commands and inspect status, while optional logging processes rotate and retain service output. The tree also includes process-setup utilities, wait helpers, and supporting runtime libraries. Relationships among sampled supervisors and utilities are clear, but several dispatch details are not excerpted, so those links are shown as unverified rather than asserted.

Main entry points: runsv.c Service supervisor · svlogd.c Log daemon · sv.c Control client · runsvctrl.c Control utility

Components 19

Service supervision

System init src/runit-init.c
Shutdown coordinator src/runit.c
Service directory src/runsvdir.c
Service supervisor src/runsv.c

Operator tools

Control client src/sv.c
Control utility src/runsvctrl.c
Status utility src/runsvstat.c
Wait for up src/svwaitup.c
Wait for down src/svwaitdown.c
Process setup src/chpst.c
Service directory changer src/runsvchdir.c
Login accounting src/utmpset.c

Logging

Log daemon src/svlogd.c
Rotated log files

Runtime utilities

C runtime primitives src/buffer.h
Time primitives src/taia.h

Other components

Service process
Administrator
Service scripts

Connections 21

System init → Shutdown coordinator: starts src/runit-init.c
Service directory → Service supervisor: dispatches
Service supervisor → Service process: executes src/runsv.c
Service supervisor → Service scripts: loads scripts src/runsv.c
Administrator → Control client: requests control
Control client → Service supervisor: writes commands
Administrator → Control utility: invokes
Control utility → Service supervisor: writes commands
Administrator → Status utility: requests status
Status utility → Service supervisor: reads status src/runsvstat.c
Wait for up → Service supervisor: checks status src/svwaitup.c
Wait for down → Service supervisor: checks status src/svwaitdown.c
Service supervisor → Log daemon: pipes output
Log daemon → Rotated log files: writes and rotates src/svlogd.c
Administrator → Process setup: invokes
Administrator → Service directory changer: invokes
Administrator → Login accounting: invokes
Service supervisor → Time primitives: uses timestamps src/runsv.c
Log daemon → Time primitives: uses timestamps src/svlogd.c
Service supervisor → C runtime primitives: uses buffers src/runsv.c
Log daemon → C runtime primitives: uses buffers src/svlogd.c

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