Ubuntu – How to boot into recovery mode if it hangs booting single user

11.10bootupstart

How can I boot into recovery mode if it hangs booting into single user mode?

I am trying to boot into "recovery mode" or any single user mode, but upstart is trying to start modem-manager no matter what. It says "modem-manager could not connect to system bus" and sits there retrying, forever.

Can I boot into single user mode and tell upstart to NOT try starting the modem?

Can I boot single user and tell upstart to start a shell after drives are mounted? Thanks for any help in advance…

UPDATE: I was able to use the grub init=/bin/bash trick to get a command prompt on booting. From there I was able to apt-get purge modemmanager. But I still get an error about can't connect to system bus and a hang. Is there a way to put upstart into extra verbose mode so I can see what is causing the hang?

Best Answer

After a lot of Googling the different terms, I found a post that may solve your problem also.

For me that was a bug for Ubuntu 11.10. Take a look at this post for solution. And to repeat the solution here:

Hit Ctrl+Alt+F1 at the blank screen to get you to a non-X terminal (tty1)
Login in with your username and password
Change to root with: sudo -i and enter your password
mkdir -p /run /run/lock
rm -rf /var/run /var/lock
ln -s /run /var
ln -s /run/lock /var
Reboot

Related Solutions

Ubuntu – How to boot into single-user mode from GRUB

To boot into single user mode you edit the boot instructions for the GRUB menu entry you wish to boot and add the kernel parameter/option single. Brief instructions for how to do this are below.

Hold down the left Shift key while rebooting to bring up GRUB menu
Select (highlight) the GRUB boot menu entry you wish to use.
Press e to edit the GRUB boot commands for the selected boot menu entry.

Look near the bottom of the list of commands for lines similar to

linux /boot/vmlinuz-3.2.0-24-generic root=UUID=bc6f8146-1523-46a6-8b\
6a-64b819ccf2b7 ro  quiet splash
initrd /boot/initrd.img-3.2.0-24-generic

Change the middle line in (4) by adding the kernel boot parameter single to the end of the line (i.e. after ro quiet splash).

For this example you would change:
```
6a-64b819ccf2b7 ro  quiet splash
```
to
```
6a-64b819ccf2b7 ro  quiet splash single
```
Press either Ctrl+X or F10 to boot using these kernel options.

Note: These changes are not persistent. Any change to the kernel boot options made this way will only affect the next boot and only if you start that boot by pressing either Ctrl+X or F10 while still in GRUB edit mode.

Ubuntu – How to boot to the recovery mode if it is not listed in Grub

The instruction Remove existing kernel options from the linux line and add single refers to changing the line

linux /boot/vmlinuz-3.5.0-26-generic root=<uuid> ro ipv6.disable=1 quirt splash $vt_handoff

linux /boot/vmlinuz-3.5.0-26-generic root=<uuid> single

which will boot up and show a text-mode terminal with root permissions ("single-user mode") from which fixes can be made.

The Ubuntu recovery mode is entered by setting linux options thusly:

linux /boot/vmlinuz-3.5.0-26-generic root=<uuid> ro recovery nomodeset

This provides a menu which automates some common system fixes, or lets you access a root shell as the single option would.

Best Answer

Related Solutions

Ubuntu – How to boot into single-user mode from GRUB

Ubuntu – How to boot to the recovery mode if it is not listed in Grub

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