[SOLVED] sysvinit detailed sequence

ilesterg · 04-09-2018, 03:56 PM

Hi!

I'm trying to figure out a boot issue on a Cent6 machine, and I'm trying to figure out what's causing it to stop booting. I can provide the exact error but I'm trying to figure that out myself. I was thinking I might need to understand the exact sequence of bootup so I was looking for documents on that, but I can't find any.

This is for cent/rhel 6 (with sysvinit, obviously), setup for runlevel 3 (/etc/inittab).

TIA.

scasey · 04-09-2018, 06:43 PM

Look at /var/log/boot.log -- that captures the messages as displayed on the screen during boot. If your logs are rotated, you'll hopefully have one without the error so you can see the entire boot sequence.

ilesterg · 04-09-2018, 08:07 PM

Thanks, that's what I am looking at, but I wish to see what actions are done per step..the thing is, one server stopped booting at some point and I was trying to trace what it was doing using the scripts in /etc/rc.d but I don't have an info on the sequence of these scripts.

I'm also attaching a screenshot of the last thing on the boot console. Any idea what I should check next? https://imgur.com/a/LHhLZ

chrism01 · 04-09-2018, 08:10 PM

Quote:

info on the sequence of these scripts.

Look in /etc/rc3.d

ilesterg · 04-10-2018, 12:53 PM

Quote:

Originally Posted by chrism01

Look in /etc/rc3.d

Yup, I understand that those are the scripts for the runlevel.

So this is the boot process:

Code:

Bios > mbr > grub > kernel > init > runlevel

I'm convinced that the issue happens somewhere between kernel loading and init 3, but I can't figure out where. Also, I understand that the following scripts are in sequence, but I can't put them in the big picture:

Code:

/etc/rc.d/rc.sysinit
/etc/rc.d/rc.local

Sorry if I'm missing something obvious here.

chrism01 · 04-10-2018, 08:49 PM

There's a good step by step here https://access.redhat.com/documentat...utdown-process.

In response to your specific qns:
/etc/init.d - contains actual service programs / daemons startup scripts
/etc/rc3.d - numbered symlinks to /etc/init.d - defines order in startup scripts are called

/etc/rc.sysinit - called just after kernel start - before rcX.d
/etc/rc.local - called absolutely last - used to eg startup a script/dameon you want where you can't be bothered to crate a proper script in init.d & assoc symlinks for various startup levels (runlevels)

HTH

ilesterg · 06-05-2018, 12:59 AM

Thanks a lot to all those who responded. Much appreciated!