From Fedora Project Wiki

(add a note about systemd change to use sulogin in rescue.service)
(use the admon/note templates correctly)
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== Entering Rescue Mode ==
 
== Entering Rescue Mode ==
 
=== Using GRUB legacy ===
 
=== Using GRUB legacy ===
{{Admon/note|GRUB legacy was the default boot loader up until Fedora 15.}}
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{{Admon/note||GRUB legacy was the default boot loader up until Fedora 15.}}
 
While your system is starting up, hold down the ''Ctrl'' key or ''Esc'' to see the boot loader menu. After you see the menu:
 
While your system is starting up, hold down the ''Ctrl'' key or ''Esc'' to see the boot loader menu. After you see the menu:
 
* Use the arrows to select the boot entry you want to modify.
 
* Use the arrows to select the boot entry you want to modify.
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=== Using GRUB2 ===
 
=== Using GRUB2 ===
{{Admon/note|GRUB2 has the default boot loader since Fedora 16.}}
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{{Admon/note||GRUB2 has been the default boot loader since Fedora 16.}}
 
While booting the system the GRUB2 menu will be displayed, to boot into the rescue mode follow these steps:
 
While booting the system the GRUB2 menu will be displayed, to boot into the rescue mode follow these steps:
 
* Use the arrow keys to select the boot entry you want to edit
 
* Use the arrow keys to select the boot entry you want to edit
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* Press '''Ctrl-x''' or '''F10''' to boot that entry
 
* Press '''Ctrl-x''' or '''F10''' to boot that entry
  
{{Admon/note|This method should work to change the root passwords up until Fedora 18, i.e. after the system finishes booting you would get a root prompt (#) which you can use to change the root password. However Due to a change in systemd - this change was in effect since Fedora 19 - booting to the rescue mode (single user mode) will prompt you to enter the root password which obviously means you can't use this method to reset the root password.}}
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{{Admon/note|Rescue Mode changes|This method should work to change the root passwords up until Fedora 18, i.e. after the system finishes booting you would get a root prompt (#) which you can use to change the root password. However Due to a change in systemd - this change was in effect since Fedora 19 - booting to the rescue mode (single user mode) will prompt you to enter the root password which obviously means you can't use this method to reset the root password.}}
  
  

Revision as of 09:16, 22 January 2014

Setting up a root password is a mandatory part of a Fedora installation. If you forget or otherwise lose your root password, there are procedures to reset it.

Fedora uses run levels to determine the services being run when you start your system. Run level 1 can be used as a rescue mode. Booting Linux under run level 1, which is also called single user mode, will display a root prompt on bootup, from which you can reset the root password.

Entering Rescue Mode

Using GRUB legacy

Note.png
GRUB legacy was the default boot loader up until Fedora 15.

While your system is starting up, hold down the Ctrl key or Esc to see the boot loader menu. After you see the menu:

  • Use the arrows to select the boot entry you want to modify.
  • Press e to edit the entry.
  • Use the arrows to go to kernel line.
  • Press a or e to append this entry.
  • At the end of the line add the word single or the number 1.
  • Press Enter to accept the changes.
  • Press b to boot this kernel.

A series of text messages scrolls by and after a short time, a root prompt appears awaiting your commands (#).

Using GRUB2

Note.png
GRUB2 has been the default boot loader since Fedora 16.

While booting the system the GRUB2 menu will be displayed, to boot into the rescue mode follow these steps:

  • Use the arrow keys to select the boot entry you want to edit
  • Press e to start editing that entry
  • Use the arrow keys to go to the line that start with linux
  • Go the the end of that line (by pressing End) add a space then the word single or the number 1
  • Press Ctrl-x or F10 to boot that entry
Note.png
Rescue Mode changes
This method should work to change the root passwords up until Fedora 18, i.e. after the system finishes booting you would get a root prompt (#) which you can use to change the root password. However Due to a change in systemd - this change was in effect since Fedora 19 - booting to the rescue mode (single user mode) will prompt you to enter the root password which obviously means you can't use this method to reset the root password.


Note.png
Encrypted partitions
Which ever GRUB version your system has, if you have an encrypted partition, you are prompted for the pass phrase before mounting the filesystems. If have more than one encrypted partition and they all share a global pass phrase, select the option for global pass phrase. Otherwise, enter the pass phrase separately for each partition.

Changing root password

As root, changing password does not ask for your old password. Run the command:

# passwd

Enter your new root password twice. Congratulations! You now have now reset your root password. You can type reboot and press enter to restart your system.

Reset Password When Boot Loader is Password Protected

  1. Boot from the install or rescue CD/DVD.
  2. Select "Rescue installed system."
  3. Answer the prompts for language and keyboard. Starting the network is optional and not needed.
  4. Let the rescue mode mount your file systems in the read/write mode.
  5. Hit Enter to get the shell prompt.
  6. At the prompt, enter the following commands. Do not enter any # mark or the text following it. These comments are shown for explanatory purposes only.
    chroot /mnt/sysimage   # Change to your disk file system
    passwd                 # Change the root password
    exit                   # Exit the chroot environment
    exit                   # Exit the rescue mode

The system now unmounts the file systems and reboots.

Reset Password When BIOS is Password Protected

If you cannot enter rescue mode because you forgot the BIOS password required to select an alternate boot device, you have three options:

  • Refer to your computer's documentation for instructions on resetting the BIOS password in CMOS memory, usually by moving a physical jumper.
  • Physically change the boot order.
  • Temporarily move the system hard disk to another machine, and follow the procedures above to reset the root password.