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Ubuntu's Success Story: the Upstart Startup Manager (Linux Boot Camp p.2)

Apr 08, 2010, 16:32 (1 Talkback[s])
(Other stories by Akkana Peck)

"Boot Camp Part I explained how Linux boots, using the old "SysV init" system of scripts. But some modern Linux distros have been gradually migrating to a newer model, called Upstart.

"Upstart has been around since 2006, but it's only in the last year or so that it's taken a major role in booting distributions like Ubuntu and Fedora. Debian and OpenSuSE are reportedly joining in soon, while it's available as an optional component on most other distros. No distro uses it as the sole boot method yet: even Fedora 12 and the upcoming Ubuntu 10.04 keep a lot of functionality in SysV scripts.

"An event-based model

"The normal SysV boot process is synchronous -- meaning things happen one at a time, one after the other. First you run S10sysklogd, and only when that's finished you can start running S11klogd. If anything in the boot process takes a long time, everything else has to wait.

"Upstart, in contrast, is event based. An "event" can be something like "booting" ... or it can be a lot more specific, like "the network is ready to use now". You can specify which scripts depend on which events. Anything that isn't waiting for an event can run whenever there's CPU available.

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