Re: [ale] systemd talk from July has slide deck online now

From: Steve Litt <>
Date: Wed, 9 Sep 2015 01:04:12 -0400

On Tue, 8 Sep 2015 18:22:04 -0700
Colin Booth <> wrote:

> s6-svscan is designed to be a stage 2 init and supervision root but
> can happily run as a non-init process under another service. Compared
> to runit, where pid1 is runit, and it forks out different scripts for
> each stage, when run as an init s6 uses a script for stage 1, execs
> into s6-svscan for stage 2, and uses a script again for stage 3. I use
> s6-svscan as an init at home and as a runsvdir/svscan (daemontools)
> non-pid1 supervision scanner at work.
> >
> > * s6-rc: This is coming out this month: I haven't used it. From
> > what I understand, this has raised the bar by combining a top
> > quality PID1 with the s6 service manager.
> >
> s6-rc has nothing to do with pid1 init and everything to do with
> solving some major problems that supervision suites have. The base s6
> service already handles init if you want it to. s6-rc is a system for
> handling service ordering dependencies and the ability to call oneshot
> scripts from inside of a supervision context.

Thanks Colin,

I used Suckless-Init as PID1 and had Suckless-Init pass the baton to
s6, using LittKit to enable service startup ordering in s6 and
intermixing oneshots and longruns in s6.

If I want to use s6 as my init, what do I do, just put into my Grub
kernel line init=/usr/bin/s6 or whatever the s6 executable is?

Is s6-rc something you add to s6, or is it a totally different thing?

Am I understanding you right that s6-rc enables you to order the
startup of managed services, and intermingle those managed services
with one-shots, as necessary?

Also, am I understanding you correctly that, when used as an init, s6
starts by running a stage 1 script, then execs itself into a
supervision program, and when the user chooses to shut down, runs the
shutdown script? If all of the above is true, it sounds challenging to
run the wait loop, to reap zombies and receive signals, in the same
PID1 that is the service manager. I guess I'll have to read the code.



Steve Litt
August 2015 featured book: Troubleshooting: Just the Facts
Received on Wed Sep 09 2015 - 05:04:12 UTC

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