Grub and Kernel parameter init=/bin/bash

sumncguy · Post by **sumncguy** » 2015/10/23 15:45:52

I just had a thought. In fact, I fire up a new VM this weekend. Do nothing to the server other than modify the kernel parameters and see what happens.

sumncguy · Post by **sumncguy** » 2015/10/26 17:49:20

From the http://centos.mirrors.wvstateu.edu/6.7/isos/x86_64/ mirror I downloaded
CentOS-6.7-x86_64-bin-DVD1.iso

I created a new VM with all defaults using VMWare Workstation.
I accepted all defaults when the OS was loading.
I allowed the OS to boot.
I opened a terminal window and entered "reboot"
I interrupted the boot loader.
When presented with the boot loader menu, I entere "a"
I then moved to the end of the Kernel boot line and added the parameter "init=/bin/bash" without quotes and hit enter.
I was brought to the prompt shown in the graphic.
The results are also shown in the graphic ...not mention of Ubuntu. \

gerald_clark · Post by **gerald_clark** » 2015/10/26 18:56:45

/com/ubuntu/upstart

AlanBartlett · Post by **AlanBartlett** » 2015/10/26 20:59:22

sumncguy wrote:From the http://centos.mirrors.wvstateu.edu/6.7/isos/x86_64/ mirror I downloaded
The results are also shown in the graphic ...not mention of Ubuntu.

Yes there is. Look at the image you have posted, line number eight (8) reads --

init: Failed to connect to socket /com/ubuntu/upstart: Connection refused

avij · Post by **avij** » 2015/10/26 21:47:30

You two are barking at the wrong tree. There really is an "init: Failed to connect to socket /com/ubuntu/upstart: Connection refused" message when CentOS 6 is booted with init=/bin/bash and init 3 is invoked. $DEITY knows why.

If normal reboot commands don't work, echo b > /proc/sysrq-trigger should do the trick.

sumncguy · Post by **sumncguy** » 2015/10/27 19:31:55

Geez finally .. thank you avij ...

sumncguy · Post by **sumncguy** » 2015/10/27 19:41:41

... and Im back to say that avij .. you, at least from my point of view, can hold the title of wizard. I have been trying to get this problem solved for maybe a week and everyone was basically saying I was crazy. Makes a new guy kind of doubt himself.

Can you explain in new guys system admin speak why there is a reference to Ubuntu and why none of the 5 "standard" methods of reboot/shutdown doesnt work ?

Thanks again for answering and solving my problem. .

gerald_clark · Post by **gerald_clark** » 2015/10/27 19:51:49

I suspect your VM doesn't to a proper BIOS emulation.

avij · Post by **avij** » 2015/10/27 20:12:04

Upstart has its origins at Ubuntu/Canonical and some labels still contain the literal "ubuntu" in them, much like there are a few references to "rhel" in CentOS. Merely changing those labels would likely break something that depends on them named "ubuntu". So they're likely to stay as is.

When a system is booted normally, upstart's init is used as the init process. When you use something else as the init process, such as /bin/bash, upstart's init won't be used. However, the shutdown, reboot, init etc. commands that are installed rely on being able to tell upstart's init that it's now time to shutdown, reboot, change to some other runlevel etc. When they're unable to contact upstart's init, odd things may happen as you've seen.

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