On 08/23/2012 03:18 PM, Pat Riehecky wrote:
> On 08/18/2012 03:57 PM, David Sommerseth wrote:
>> Hi,
>>
>> I've been running Scientific Linux since the 6.0 days, and single-user mode
>> have basically behaved how I have expected it those few times I needed it.
>> As I usually set up my boxes root accounts with passwords disabled,
>> single-user mode needs to be without root password.
>>
>> Today, after having upgraded from 6.3, I needed to enter single-user mode at
>> boot. And I was asked for a password at boot time. Is this change intentional?
>>
>> # cat /etc/redhat-release
>> Scientific Linux release 6.3 (Carbon)
>> # rpm -qa | grep -i sl_password_for_singleuser | wc -l
>> 0
>> # grep SINGLE /etc/sysconfig/init
>> SINGLE=/sbin/sushell
>>
>> If this change was intentional, how can I go back to the old behaviour? I
>> double checked the behaviour with an old VM with SL6.1, and that behaves as
>> expected.
>>
>>
>> kind regards,
>>
>> David Sommerseth
>
> Hi David,
>
> The behavior shouldn't have changed. You've provided just about all the
> relevant details in your email, so there isn't really anything I want to ask
> for more information.
>
> Can I have you try setting /etc/sysconfig/init => SINGLE to /sbin/sulogin
> rebooting and setting it back to /sbin/sushell? Perhaps something got 'stuck'
> wrong....
>
> /sbin/sushell is a shell script, so can I have you verify its contents? Mine
> looks like:
>
> #!/bin/bash
>
> [ -z "$SUSHELL" ] && SUSHELL=/bin/bash
>
> exec $SUSHELL

Hi Pat,

First of all, tanks a lot for your answer, and to Stephan for his input as 
well.  I checked /sbin/sushell and the SINGLE variable in /etc/sysconfig/init. 
  And it was currently working just as expected - in both modes.

But as I knew it had been failing, I added an extra disk to the VM I have with 
SL6.3.  Double checked adding 's' to the kernel command line gave me a shell 
without asking for password.  Then I added this disk to /etc/fstab ... and 
removed the extra disk.  This time, I was asked for a root password when 
booting up - both when I was asking for 's'ingle user-mode and without it. 
Adding the disk back, and the "proper" behaviour is back too.

So that's the issue I hit, as I in my real setup had just added and configured 
a new disk with encryption on my VM - but messed up the encryption key.  When 
I then wanted to rescue the system, instead of solving it via 'single-user 
mode' I had to use guestfish on the root filesystem of the failing machine and 
disable the new disk in /etc/cryptotab and /etc/fstab.  Then I could start 
setting up the disk again with a proper key.

But the hint from Stephan, setting EMERGENCY=/sbin/sushell in 
/etc/sysconfig/init did the trick.  So that's what I need to set on all my boxes.

Lesson learnt: Emergency mode supersedes single-user mode, especially with 
filesystem failures.


Thanks all!


kind regards,

David Sommerseth