วิธีการเปลี่ยน password ให้ทำตามนี้
4.4 Losing Your Root Password
If for some reason you lose your root password you can change it by following these steps:
1) Reboot your machine.
2) From GNOME, log out, and choose the reboot option. Or from the login screen, click ‘System’ then ‘Reboot’. From console mode, press Ctrl-Atl-Del (which in Linux reboots the system in a controlled fashion). You will see the shutdown sequence begin.
3) Allow the system to reboot to the GRUB splash screen, and then press “e”. Select the line containing “kernel”, and press “e” again. GRUB will display the line in edit mode.
4) Add “single” to the end of the line, and press return. GRUB will return you to the previous screen.
5) Press “b” to boot the system into what will now be single user mode. The system will come part of the way up, and then drop you into a root shell – the prompt will look like this: sh-2.05# _
6) Type “passwd” and press return. The system will ask you for a new password. Type in your new password, then to retype it as confirmation (it will not display on the screen). If the two entries do not match, it will ask you to try again. It will also warn you if it thinks the password is too obvious; you can ignore the warning, but if you are on a computer that either isn’t behind a firewall or is in a public area, this is not recommended.
7) Once the new password is in place, type “exit” and press return to allow the system to finish booting. Passwords should be something you can remember without writing down, but not something anyone else could figure out. Dictionary words and passwords that are all numbers are not recommended. Subtle misspellings, funny capitalizations (Linux is case sensitive), and substituting numbers or special characters for letters make good passwords. For instance, the first letters of the words in a phrase can work, too. Some good examples are:
With the new MD5 password security, passwords are no longer limited to eight characters as in older versions of UNIX. The limit is on your own memory, typing accuracy, and patience.
Important: Please remember to change the default root password as soon as you become acqainted with your system.