How to boot into Single user mode

[M Merajuddin]

We changed the yp host on our domain. Upon doing so
one of our HP/UX K220 UX 10.10 is not letting us log
on as any user, incuding root.

Question(s):
- Is there anyway to log on to system without going into single user mode
- How do I boot this machine into single user mode, so that I can log on and
disable yp?
Detail steps would really be helpful.

I am embarassed to ask, the HP Admin is on vacation and I only handle AIX. Ive
tried moving the Key to the Service (Wrench) mode, but dont see any options
that will take me to single user mode. Other crisis have not allowed me to
review any On/Off-line documentations
if they are available.

Thanks in Advance!

[Mitch Wolf]

Hi

Not sure why you can't log in as root if you are on console unless
/etc/securetty is not right. Anyway if you are logged in.
#/sbin/shutdown - will boot to single user.

If you cannot log in at all then a hard reset will be needed. At console do
1)ctrl/b 2)rs 3)Y to confirm.
When system boots you will get a 10sec interupt boot process press a key at
this time.

01)Y - continue boot process
02)Y - to interact with isl
03)isl: hpux -is will boot to single user
fix whatever is needed then do
#/sbin/reboot

also cat /etc/securetty to see whats there console
should be listed if file exists

hope this helps

Mitch

[Evan Day_1]

See Mitch Wolf's followup for instructions on how to get into single user mode.

Regarding NIS, though, you should check (as well as you can) that there is an
entry for root in your /etc/passwd file. Even when using NIS for password
lookups it's strongly advised to keep root in your local /etc/passwd and set up
/etc/nsswitch.conf to fallback to files in the event that the NIS
masters/slaves are down.

You should have an entry in /etc/passwd that reads:
root:encrypted_password:0:3::/sbin/sh

Then, in /etc/nsswitch.conf, look for this line:
passwd: compat

-or-

passwd: nis [NOTFOUND=continue] files

Hope this wasn't too confusing...
-Evan

[M Merajuddin]

Both responses were very helpful in resolving my
problems!

Thank you Very Much!

[Thomas Bradley, jr.]

Hello everyone,
I'm running HP-UX 10.20 and whenever I bring the system into single-user mode
by executing the command - init S or s I am still able to telnet into the
system from a Windows workstation. I am trying to complete system backups on a
server housing several Oracle databases and if I can telnet into the system it
must be possible for our DBAs to restart the database and process transactions
while the database is running rendering my backups useless. Would appreciate
any help in solving this problem. Thanks.


--- Thomas

[Alan Riggs_1]

The command "shutdown -y 0" will drop your system to single user mode. If your
goal is simply to prevent database activity, though, it probably makes more
sense to shutdown your databases for cold backups without dropping the rest of
your system into single-user.

[Vibert Hart_2]

Well,

There may be two solutions to your problem.

1. Work with you DBA to do "Hot-Backups", the database could be open while the
backups are going. Of course the database needs to be in archive log mode. The
DBA can write a script that logs in "svrmgrl" and issue the command "alter
tablespace begin backup. Then at OS level you cp or fbackup.

2. The simulate the single user mode you could write a script that is called
from the /etc/profile file, that check for user names in a file list. If name
not there then exit. Of course "root" needs to be there.

Vibert