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Single User Mode - Boot Recovery

Use single user mode to assist in troubleshooting system boot issues or for password recovery. Entering single user mode is platform-specific, so follow the appropriate steps for your x86 or ARM switch.

Entering Single User Mode on an x86 Switch

  1. Boot the switch, as soon as you see the GRUB menu.

                           GNU GRUB  version 2.02~beta2-22+deb8u1
         
     +----------------------------------------------------------------------------+
     |*Cumulus Linux GNU/Linux                                                    | 
     | Advanced options for Cumulus Linux GNU/Linux                               |
     | ONIE                                                                       |
     |                                                                            |
     +----------------------------------------------------------------------------+     
    
  2. Use the ^ and v arrow keys to select Advanced options for Cumulus Linux GNU/Linux. A menu similar to the following should appear:

                           GNU GRUB  version 2.02~beta2-22+deb8u1
         
     +----------------------------------------------------------------------------+
     | Cumulus Linux GNU/Linux, with Linux 4.1.0-cl-1-amd64                       | 
     | Cumulus Linux GNU/Linux, with Linux 4.1.0-cl-1-amd64 (sysvinit)            |
     |*Cumulus Linux GNU/Linux, with Linux 4.1.0-cl-1-amd64 (recovery mode)       |
     |                                                                            |
     +----------------------------------------------------------------------------+  
    
  3. Select Cumulus Linux GNU/Linux, with Linux 4.1.0-cl-1-amd64 (recovery mode).

  4. Press ctrl-x to reboot.

  5. After the system reboots, set a new password.

    # passwd
    Enter new UNIX password: 
    Retype new UNIX password: 
    passwd: password updated successfully
    
  6. Reboot the system:

    # sync
    # reboot -f
    Restarting the system. 
    

Entering Single User Mode on an ARM Switch

  1. From the console, boot the switch, interrupting the U-Boot countdown to enter the U-Boot prompt. Enter the following:

    => run cl_bootrecover
    
  2. After the system boots, the shell command prompt appears. In this mode, you can change the root password or test a boot service that is hanging the boot process.

    Welcome to rescu
    root@switch:~# passwd
    Enter new UNIX password: 
    Retype new UNIX password: 
    passwd: password updated successfully
    
  3. Reboot the system.

    root@switch:~# reboot
    Restarting the system.