Not able to log into single user mode.

pinga123 · 03-02-2011, 11:33 PM

Hi as per the article given.
http://www.cyberciti.biz/faq/grub-bo...gle-user-mode/

I m modifying the boot entry

Code:

grub edit> kernel /vmlinuz-2.6.18-92.el5 ro root=/dev/VolGroup00/LogVol00 rhgb quiet Single

and then booting from it by pressing b.
However the machine is getting booted into runlevel 5.

if the above entry is modified as

Code:

grub edit> kernel /vmlinuz-2.6.18-92.el5 ro root=/dev/VolGroup00/LogVol00 rhgb quiet 1

then it goes into runlevel 1.

I just want to know why Single word is not working?
and
Is booting the system into runlevel 1 is same as single user mode?

corp769 · 03-02-2011, 11:40 PM

Have you tried using "single" and not "Single?" (Notice I didn't capitalize the S in single....)

pinga123 · 03-02-2011, 11:46 PM

Quote:

Originally Posted by corp769

Have you tried using "single" and not "Single?" (Notice I didn't capitalize the S in single....)

Yes i tried that but machine get booted to an environment which looks similar to single user mode but when i type runlevel is says unknown.

Code:

#runlevel
unknown

corp769 · 03-02-2011, 11:50 PM

Try it by adding the following and see if it helps:

Code:

rw init=/bin/bash

pinga123 · 03-02-2011, 11:55 PM

Quote:

Originally Posted by corp769

Try it by adding the following and see if it helps:

Code:

rw init=/bin/bash

modified the entry as below

Code:

grub edit> kernel /vmlinuz-2.6.18-92.el5 ro root=/dev/VolGroup00/LogVol00 rhgb quiet rw init=/bin/bash single

Now i m getting an error as

Code:

/bin/bash :single : no such file or directory
Kernel panic - Not syncing attempting to kill init!

corp769 · 03-03-2011, 12:03 AM

I didn't tell you to add "rw init=/bin/bash single"... I told you to add the following:

Code:

rw init=/bin/bash

pinga123 · 03-03-2011, 12:09 AM

Quote:

Originally Posted by corp769

I didn't tell you to add "rw init=/bin/bash single"... I told you to add the following:

Code:

rw init=/bin/bash

i apologize it was my mistake.
I have tried with following parameter

Code:

grub edit> kernel /vmlinuz-2.6.18-92.el5 ro root=/dev/VolGroup00/LogVol00 rhgb quiet rw init=/bin/bash

Now i m at bash prompt.

Code:

bash-3.2#runlevel
bash :runlevel: command not found

Can you please explain the use of rw init=/bin/bash.

corp769 · 03-03-2011, 12:15 AM

It just gives you a simple bash shell; single user mode for minimal system maintenance. And most likely /usr is not mounted; Type "mount /usr" and you should be set.

pinga123 · 03-03-2011, 12:45 AM

Quote:

Originally Posted by corp769

It just gives you a simple bash shell; single user mode for minimal system maintenance. And most likely /usr is not mounted; Type "mount /usr" and you should be set.

Ok thanks for the explaination.
But my question is still unanswered .
Why m i not able to login into single user mode using Single or single keyword(Is this method not universal)?
Is runlevel 1 is similar to single user mode?
do i need to apply various parameters to log into single user mode?
Which method is universal?

sumeet inani · 03-03-2011, 12:58 AM

for grub2

Quote:

1. If you have Grub 2 set to boot without displaying the menu at all, hold the SHIFT key down until the menu displays. (In Grub it was the ESC key.)
2. Press any key once the menu is displayed to 'freeze' it. Then arrow to the kernel you want to boot.
3. Press "e"
4. Scroll to the end of the "linux /boot/vmlinuz...." line. If displayed, remove "quiet" and/or "splash". Add the word "single" to the end of the line.
5. Press CTRL-X to boot to the Recovery menu.

from http://ubuntuforums.org/showthread.php?t=1195275

pinga123 · 03-03-2011, 01:28 AM

Quote:

Originally Posted by sumeet inani

for grub2

from http://ubuntuforums.org/showthread.php?t=1195275

Finding it very difficult no newbie like me.
are there diff versions of grub available as i m not able to boot using ctrl +x after editing the lines?

sumeet inani · 03-03-2011, 01:54 AM

Quote:

"Single-user mode was traditionally init level 1. It brought down all
multiuser and remote login processes and made sure the system was
running a minimal complement of software. Since single-user mode
provides root access to the system, however, administrators wanted
the system to prompt for the root password whenever it was booted
into single-user mode. The S run level was created to address this
need: it spawns a process that prompts for the root password. On
Linux, the S level serves only this purpose and is not a destination
in itself."

from http://marc.info/?l=redhat-list&m=102242207300936&w=2