1) Break the boot sequence by adding ‘rd.break’ at kernel stanza in grub. To do this, restart your system and when the GRUB splash screen comes:
Select/highlight the kernel you wish to boot using the up/down arrow keys.
Press the e key to edit the entry.
Select/highlight the line starting with the word kernel or linux.
Press the e key to edit the line.
Add ‘rd.break’ at the end.
Press ENTER to accept the changes.
Press the ‘ctrl + x’ key to boot the kernel with the modified command line.
2) The system will provide a shell which will be from initramfs:
Entering emergency mode. Exit the shell to continue.
Type "journalctl" to view system logs.
You might want to save "/run/initramfs/rdsosreport.txt" to a USB stick or /boot
after mounting them and attach it to a bug report.
3) Root filesystem will be mounted read-only at ‘sysroot’ directory:
switch_root:/# mount | grep -i sysroot
/dev/mapper/rhel-root on /sysroot type xfs (ro,relatime,attr2,inode64,noquota)
4) Remount it with read-write mode:
switch_root:/# mount -o remount,rw /sysroot
5) Chroot into it:
switch_root:/# chroot /sysroot/
6) Change the password:
Changing password for user root.
BAD PASSWORD: The password is shorter than 8 characters
Retype new password:
passwd: all authentication tokens updated successfully.
I had to use the following step to reset a the root password on a Solaris system the other day. You will need physical access to the system to use these steps.
Press Stop-A on the console or Ctrl-] and send brk from a remote console connection to access the Open Boot PROM (OBP).
NOTE : If you are using TeraTerm-Pro, you send a break from the menu.
Insert a bootable Solaris CD/DVD and boot into single-user mode with boot cdrom -s
If a JumpStart boot server is located on the system’s subnet, and the system was properly configured for JumpStart, you may instead boot over the network into single-user mode with boot net -s
Make a mount point within the /tmp file system by typing mkdir /tmp/mnt
Mount the root partition of your boot disk in /tmp/mnt
e.g. #> mount /dev/dsk/c0t0d0s0 /tmp/mnt
NOTE : To check the device name use the format command.
Edit /etc/shadow with TERM=vt100 vi /tmp/mnt/etc/shadow
Remove the encrypted part of the root password (the second field; fields are separated by colons), save, and exit.
Unmount the file system with umount /tmp/mnt
Reboot the system and assign a new password at a shell prompt with the passwd command.
If you are unable to run vi above, you can edit /etc/shadow using the ed editor.
# ed /tmp/mnt/etc/shadow
s/:………….:/::/ (Note: there are 13 dots in the second field)
We’ve had an Oracle Manage Server (OMS) running here at work for some time now. I think it was setup by a DBA who worked here years ago. The previous DBA didn’t use it so when I came to the job he told me to just login locally to OEM and not worry about using it.
I had some spare time the other day and thought I would have a look into what it could do. One of the first problems I ran into though was that I had to reset my password. Of course I didn’t have the admin password, and the last DBA doesn’t work here any more. So I had to find out how to reset the sysman password. Continue reading Resetting the OMS password