topic Re: sigle user mode in Operating System - HP-UX

sigle user mode

khilari — Sun, 01 Jan 2006 15:45:26 GMT

Hi people, i was looking for a document or something regarding all the activities and actions one can do once he is in the single user mode. Any suggestions

Re: sigle user mode

Bill Hassell — Sun, 01 Jan 2006 19:19:04 GMT

Single user mode is a special condition where there is no networking, no services (like printing) and no applications are started. Nothing is mounted except / and /stand. So at the very start of single user mode, only the commands founf in /sbin are available.

You'll see commands like vi are missing, but no problem--just mount the 3 required filesystems:

mount /var
mount /tmp
mount /usr

and now in single user mode, you can run vi and most of the commands in /usr/bin. Some commands in /usr/bin will not work because they need networking started.

Re: sigle user mode

Chauhan Amit — Mon, 02 Jan 2006 01:24:23 GMT

As explained by Bill Single user mode is a special condition where there is no networking, no services (like printing) and no applications are started.

Here are the major actions which you can do:

a) Change root password
b) Check system logs for error messages , if your system is not booting to Multi-user mode.
c) check network logs to isolate networking related issues
d) check scripts which are failing during startup and modify them using vi

Here is the procedure to go to the single user mode:

Step1. During the systemâ s boot sequence it will usually wait and display the following or
similar messages if Autoboot is enabled:
Processor is booting from first available device.
To discontinue, press any key within 10 seconds.

Step2. Press any key before the 10 seconds elapses.
Step3. If the primary or alternate boot path is set correctly, you may boot using the
commands boot pri or boot alt, respectively.
Step4. The system console will display a message similar to the following:
Interact with IPL (Y, N, or Cancel)?>
Enter y at the prompt, otherwise, the command specified in the Auto-File String is
executed.

Booting...
Boot IO Dependent Code (IODC) revision 1
HARD Booted.
ISL Revision A.00.43 Apr 12, 2000
ISL>

Step5. At the the ISL> prompt you have many possible options to continue.
â ¢ For standard Multi User Mode boot:
hpux
â ¢ For Single User Mode boot:
hpux â i

Re: sigle user mode

Muthukumar_5 — Mon, 02 Jan 2006 01:27:49 GMT

He can able to,

1) change root passwd when expired and deactivated
2) Stop to give access to lan access
3) Not able to use NFS
4) Getting all privillages

Refer http://docs.hp.com/en/B2355-60127/init.1M.html this.

-Muthu

Re: sigle user mode

Arunvijai_4 — Mon, 02 Jan 2006 01:34:46 GMT

Hello, Single user mode is mainly for system administrator's purpose to maintain and troubleshoot the server. You can analyse log files, change root password, modify mount options, etc.. ..

http://www.faqs.org/faqs/hp/hpux-faq/section-255.html

-Arun

Re: sigle user mode

Sivakumar TS — Mon, 02 Jan 2006 09:22:46 GMT

Dear Mujtaba,

Check out this link....

http://www.westwind.com/reference/OS-X/commandline/single-user.html

Its good !

With Regards,

Siva.

Re: sigle user mode

Raj D. — Mon, 02 Jan 2006 12:57:49 GMT

Hi Mujtaba ,

In short , single user mode used for debugig , and troubleshooting purpose , and as described above.

Usually , for reseting root password , or for any FS related issues , or checking logfiles , we can use single user mode. If any device driver or service causing problem in Multiuser mode i.e runlevel 3 or 4 , you can also start in single user mode and mount /usr and troubleshoot that , and check in /sbin/rc3.d/S... files.

Hope this will help,

hth,
Raj.

Re: sigle user mode

Kent Ostby — Mon, 02 Jan 2006 14:57:06 GMT

Basically, you are gaining root access to the system with a bare minimum of of services started up.

Once you are there, you can do anything.

You can change passwords, mount filesystems, start networking, etc.

You will be booted with only the root VG active and with nothing mounted except slash.

So if you want to use vi, you need to follow the instructions listed above.

Re: sigle user mode

Ted Buis — Thu, 05 Jan 2006 18:27:10 GMT

It is best to boot up in single user mode rather than trying to use init to drop down to it. That isn't always clean. Another use for single user mode, if you don't have OnLineJFS and need to expand the lvols /var, /usr, or /opt. Since they have to be unmounted to do this, single user mode is one easy way to do it.