If you lost the root password on system running HP-UX, perform the following steps:
Ask all other users to log off the workstation.
Type the command sync four times to clear the buffer cache.
If you have installed sudo, or if you have enabled a user other than root to reboot the machine, reboot your workstation.
If you can not reboot the machine, press the reset button to force a reboot. Don’t press the reset button unless you can’t get the machine to reboot any other way.
During the reboot, press the ESC key to interrupt the reboot.
This will bring you to the BOOT_ADMIN prompt. From here, boot to the ISL with the command boot scsi.X.0 isl where scsi.X.0 is the SCSI address of your internal disk drive. (To find that address, use the path command at the BOOT_ADMIN prompt.)
Now you are at the ISL prompt. Boot up into single user mode with the command hpux -is (or if you are still running 9.X use the command hpux -is boot disk(scsi.X;0)/hp-ux, where again scsi.X.0 is the SCSI address of your internal disk drive.)
After the machine has come up in single user mode, you can try to set the root password by running the passwd command. If the program will run, you can enter the new password now. Reboot again (command reboot) and you are done.
If the passwd program will not run in the single user mode, manually edit the /etc/passwd file (be careful!) and take out the root password (second field), leaving the 2 colons side by side.
Now, quickly reboot the machine (reboot) and log in as root. No password is required. Immediately run the passwd command and set a password for root.
It’s important to minimize the time between removing the root password from the /etc/passwd file and resetting the password with the passwd command.
During this time, your system is wide open.