Forgot root password in LINUX ?

Resolution:

You can change your root password from single user mode or rescue mode. Getting into single use mode depends on your bootloader:

GRUB

Booting into single user mode using GRUB is accomplished by editing the kernel line of the boot configuration. This assumes that either the GRUB boot menu is not password protected or that you have access to the password if it is.

If the GRUB boot menu is password protected and you do not have access to the password, then you will need to use a rescue disk to boot the system. Follow the instructions given by the rescue disk boot process to recover your installation and then chroot to your system image (usually accomplished by issuing the command chroot /mnt/sysimage). From this point you should be able to use the passwd to change the root password of the system.

At the boot prompt, select the kernel that you wish to boot with and press 'e' (for edit). You will now be taken to a screen where you can edit the boot parameters. Move the cursor to the kernel line and press 'e' again. Now append an 'S' to the end of the line, press Return, and then 'b' (for boot). The system will now start in single user mode and you can change the root password using the passwd command.

LILO

When the system comes to the LILO: prompt, type linux single . When you get the # prompt you will need to type passwd root. This will update the password to a newer one. At this point you can type exit and your system should return to the boot sequence. Alternatively, you can reboot your system with the shutdown -r now or reboot commands. The system should boot up normally. You can now use your new root password to gain root access.

If LILO is configured to not wait at the boot menu (timeout value in /etc/lilo.conf set to 0) you can still halt the boot process by pressing any key in the split second before LILO boots the kernel.

Forgot BIOS Password

To fetch the BIOS password , you will need:

• A #1 or #2 Phillips-head screwdriver, or (less likely) a T-15 TORX driver or a 1/4" hex nutdriver, to open the case

• Needle-nosed pliers if you are working with jumpers

• A small flashlight or headlamp

With tools at hand, perform the following steps:

1. Turn the PC off (this means a total shutdown, not merely standby or hibernate mode) and disconnect the AC power cord.

2. Remove the cover from your system (this step may require tools, undoing a thumbscrew, or flipping a latch or two).

3. Refer to the user manual for the motherboard to find out how to "reset CMOS" memory. You may also find a label for specific jumper or switch settings marked on the system board.

4. Change the switch setting or jumper position to a specific position or remove the jumper entirely as prescribed in the manual to clear or reset the CMOS memory.

5. Wait 20-30 seconds for the memory to clear out from lack of power.

6. After 20-30 seconds put the switch or jumper the way it was before for normal use.

7. Reconnect the power cord and start up the system to see if the settings have changed to defaults.

8. Shut the PC down, disconnect the power cord, replace the cover, reconnect the power, and power up the PC.

9. Enter the BIOS setup program to configure the system as needed. This may include setting the date and time, selecting disk drive parameters, and selecting which devices the system uses to boot up with first.

If your system does not have a "reset CMOS" jumper or switch , the only option is to locate and remove the coin-style battery cell (or on some very old PCs, the battery pack), as shown in , that provides the power to the CMOS memory.