In all honesty, this fix really depends on what os loader your box is running on. Normally on modern linux distros like entreprise 4 , the loader will be GRUB.

in this case, how to load Grub into single user mode? :

Restart your box, and when the GRUB splash screen appears follow these steps:

1. Select/highlight the kernel you wish to boot using the up/don arrow keys.
2. Press the e key to edit the entry.
3. Select/highlight the line starting with the word kernel.
4. Press the e key to edit the line.
5. Append the letter S to the end of the line.
6. Press ENTER to accept the changes.
7. Press the b key to boot the kernel with the modified command line.

This will take you into single user mode and should provide a bash shell to execute commands.

Once you have shell access, you will probably need to chroot to your system using the command:

chroot /mnt/sysimage

From this point on you probably can use the passwd command to change the root password.


In you are using the LILO boot loader, when you see the LILO promt, type: linux single
When you reach the # prompt, type:

passwd root

Once you reset the password you can then reboot and boot your box normally.

IF LILO is not set to wait at the boot menu, you can halt the boot process by pressing any key in the split second before lilo tries to boot the kernel.

By the way, in case you want to change the lilo timeout value, you can do it from:

/etc/lilo.conf  ( 0 means no wait )

Cheers
Felipe