Init : someone could comment this ?

[Linus Walleij]

On Tue, 8 Jan 2008, Les Mikesell wrote:

> People running fedora will expect to use sysV style init configuration to 
> control it.

Now, I think Lennart is right in pushing the concept behind Upstart and 
the new InitKit, both of which break the init config paradigm and its 
runlevels.

The reason was actually outlined in Miguel de Icaza's "Let's Make Unix Not 
Suck" a few years back. It outlined some weaknesses of the Unix pipe and 
filter and signalling system: pipes are unidirectional, data is not typed, 
signals are crude in essence. Component-based thinking through CORBA led 
to the invention of Bonobo, then the condensed DCOP and eventually D-Bus 
which actually does the tricks most sought after: bidirectional messages 
between processes, typed messages, a strict namespace, broadcast messages.

The SysVInit system currently suffers from not being able to use such a 
mechanism.

Upstart solved it, basically, but has some design flaws and is used in 
init-compatibility mode in Ubuntu. So now InitKit is coming along.

It's worth sacrificing runlevels to reach the next step of unsucky Unix.

POSIX does not mandate init and its runlevels, nor does the Single Unix 
spec. I think there is a good reason for: it was awkward, so it wasn't 
standardized. If everyone though it was a good idea they would have 
standardized it back when POSIX was written. (I wasn't a member of the 
committes tho, so who knows.)

Linus