Software
skarnet.org

s6-linux-init

What is it ?

s6-linux-init is a set of minimalistic tools used to create a s6-based init system, including a /sbin/init binary, on a Linux kernel.

The resulting architecture follows the Unix philosophy (one job → one tool) as closely as possible, and is fully dedicated to the s6 way of managing a system:

• s6-svscan runs as process 1 for the whole machine lifetime.
• Every daemon is supervised.
• No logs are ever lost.
• Policy is entirely left to the user. Typically, any service manager can be run on top of s6-linux-init.

Nevertheless, the architecture is fully compliant with various empirical and historical specifications. For instance, it provides:

• utmp management compatible with sysvinit
• runlevel management, with a configurable default, overridable from the kernel command line
• sysvinit-like commands to shut the system down, including a shutdown command that follows the LSB specification

• Why s6-linux-init ?
• An overview of s6-linux-init
• A quickstart guide for the impatient

Installation

Requirements

• A Linux-based system with a standard C development environment
• GNU make, version 3.81 or later
• skalibs version 2.9.0.0 or later
• execline version 2.5.2.0 or later
• s6 version 2.9.0.0 or later

The following optional dependencies are also supported:

• If you're using musl and want nsswitch-like functionality: nsss version 0.0.2.0 or later
• If you want secure utmp functionality: utmps version 0.0.3.0 or later

All those dependencies are build-time and run-time, except possibly skalibs, which is not needed at run time if you are linking all the other packages against the static version of libskarnet.

Licensing

s6-linux-init is free software. It is available under the ISC license.

Download

• The current released version of s6-linux-init is 1.0.3.0.
• Alternatively, you can checkout a copy of the s6-linux-init git repository:

   git clone git://git.skarnet.org/s6-linux-init 

• There's also a GitHub mirror of the s6-linux-init git repository.

Compilation

• See the enclosed INSTALL file for installation details.

Upgrade notes

• This page lists the differences to be aware of between the previous versions of s6-linux-init and the current one.

Reference

General

• A rationale for this package
• An overview of s6-linux-init
• A quickstart page

Commands

Unless more details are provided in an Exit codes section of a specific page, all these commands exit 0 on success, 111 if they encounter a temporary error (such as a system call failure) and 100 if they encounter a permanent error (such as a misuse).

• The s6-linux-init-maker program
• The s6-linux-init program
• The s6-linux-init-hpr program
• The s6-linux-init-shutdown program
• The s6-linux-init-shutdownd program
• The s6-linux-init-telinit program
• The s6-linux-init-logouthookd program
• The s6-linux-init-echo program
• The s6-linux-init-umountall program

Related resources

• s6-linux-init is discussed on the skaware and supervision mailing-lists.
• There is a #s6 IRC channel on Freenode. Sometimes people are there and even answer questions.