Petter Reinholdtsen: What should start from /etc/rcS.d/ in Debian

What should start from /etc/rcS.d/ in Debian - almost nothing?

2011-07-30 14:00

In the Debian boot system, several packages include scripts that -are started from /etc/rcS.d/. In fact, there is a bite more of them -than make sense, and this causes a few problems. What kind of -problems, you might ask. There are at least two problems. The first -is that it is not possible to recover a machine after switching to -runlevel 1. One need to actually reboot to get the machine back to -the expected state. The other is that single user boot will sometimes -run into problems because some of the subsystems are activated before -the root login is presented, causing problems when trying to recover a -machine. A minor point is that moving more scripts out of rcS.d/ and -into the other rc#.d/ directories will increase the amount of scripts -that can run in parallel during boot, and thus increase the speed -time.

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So, which scripts should start from rcS.d/. In short, only the -scripts that _have_ to execute before the root login prompt is -presented during a single user boot should go there. Everything else -should go into the numeric runlevels. This means things like -lm-sensors, fuse and x11-common should not run from rcS.d, but from -the numeric runlevels. Today in Debian, there are around 115 init.d -scripts that are starte from rcS.d/, and most of them should be moved -out. Do your package have one of them? Please help us make single -user and runlevel 1 better by moving it.

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Scripts setting up the screen, keyboard, system partitions -etc. should still be started from rcS.d/, but there is for example no -need to have the network enabled before the single user login prompt -is presented.

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As always, things are not so easy to fix as they sound. To keep -Debian systems working while scripts migrate, the scripts need to be -moved from rcS.d/ to rc2.d/ in reverse dependency order, ie the -scripts that nothing in rcS.d/ depend on must be moved first, and then -this migration must be done sequencially while we ensure that the -package system upgrade packages in the right order to keep the system -state correct. This will require some coordination when it comes to -network related packages, but most of the packages with scripts that -should migrate do not have anything in rcS.d/ depending on them. Some -packages have already been updated, like the sudo package, while -others are still left to do. I wish I had time to work on this -myself, but real live constrains make it unlikely that I will find -time to push this forward.

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Tags: bootsystem, debian, english.

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- Petter Reinholdtsen - -

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