Resetting root password by booting into Single User Mode from Linux GRUB

2021-07-05 By Aaron 72850 Views linux single user mode root password

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The root is the username or account that, by default, has access to all commands and files on a Linux or other Unix-like operating system. It is also referred to as the root account, root user, and superuser.

For the LayerStack client, you can use LayerPanel and click Reset Password for resetting the new password directly.

resetserverpassword

In case if you are using the ISO method for installing the Linux operation system, then you have to use Single User Mode to reset the root password.

This guide outlines the steps to reset root passwords in various Linux distributions such as CentOS, Ubuntu and Debian.

CentOS 8

Log in to the server via Console option from LayerPanel v2.0 and click Send CtrlAltDel button to reboot the server and access the boot menu.
Once the GRUB boot prompt shows up telling to press any key, perform this action to enter the GRUB prompt. (There will only be a few seconds to press a key to stop the automated booting process if this is not done on time, the server would need to be restarted again)
From the GRUB boot prompt, press the E button to edit the first boot option.
Find the kernel line starting with linux and change ro to rw init=/sysroot/bin/sh.
```
# rw init=/sysroot/bin/sh
```
Press CTRL+X or F10 to save the changes and boot the server into single-user mode.
Access the system with the below command.
```
# chroot /sysroot
```
Type in the command passwd to set the new password. The password would need to be entered twice.
```
# passwd
```
Run the below command to force file-system relabeling.
```
# touch /.autorelabel
```
Reboot the system: reboot -f.
```
# reboot -f
```
Wait for some time, as the relabeling will take a few minutes to get completed. Once this is completed, the server will be restarted once again automatically.
Test the newly reset password once the login screen shows up.

CentOS 7

Log in to the server via Console option from LayerPanel v2.0 and click Send CtrlAltDel button to reboot the server and access the boot menu.
Once the GRUB boot prompt shows up telling to press any key, perform this action to enter the GRUB prompt. (There will only be a few seconds to press a key to stop the automated booting process if this is not done on time, the server would need to be restarted again)
From the GRUB boot prompt, press the E button to edit the first boot option.
Find the kernel line starting with linux16 and change ro to rw init=/sysroot/bin/sh.
```
# rw init=/sysroot/bin/sh
```
Press CTRL+X or F10 to save the changes and boot the server into single-user mode.
Access the system with the command: chroot /sysroot and press ENTER.
```
# chroot /sysroot
```
Type in the command passwd to set the new password. The password would need to be entered twice.
```
# passwd
```
Reboot the system: reboot -f.
```
# reboot -f
```
Test the newly reset password once the login screen shows up.

Alternative Method for CentOS 8 & 7

Log in to the server via Console option from LayerPanel v2.0 and click Send CtrlAltDel button to reboot the server and access the boot menu.
Once the GRUB boot prompt shows up telling to press any key, perform this action to enter the GRUB prompt. (There will only be a few seconds to press a key to stop the automated booting process if this is not done on time, the server would need to be restarted again)
From the GRUB boot prompt, press the E button to edit the first boot option.
At the GRUB menu, select the kernel line starting with linux16 and press END key. This will take you to the end of the line. Here type in rd.break console=tty1.
```
# rd.break console=tty1
```
Press CTRL+X or F10 to save the changes and boot the server into single-user mode.
The server will be booted into the switch-root prompt.
When using rd.break, the system will be directly mounted on /sysroot in read-only mode and it needs to be remounted in read/write mode. The below command helps in this.
```
# mount -o remount,rw /sysroot
```
Switch into a chroot jail using the below command, where /sysroot is treated as the root of the filesystem tree.
```
# chroot /sysroot
```
Type in the command passwd to set the new password. The password would need to be entered twice.
```
# passwd
```
Reboot the system: reboot -f.
```
# reboot -f
```
Test the newly reset password once the login screen shows up.

CentOS 6

Log in to the server via Console option from LayerPanel v2.0 and click Send CtrlAltDel button to reboot the server and access the boot menu.
Once the GRUB boot prompt shows up telling to press any key, perform this action to enter the GRUB prompt. (There will only be a few seconds to press a key to stop the automated booting process if this is not done on time, the server would need to be restarted again)
From the GRUB boot prompt, press the E button to edit the first boot option.
At the GRUB menu, select the line that starts with kernel and then press the E button to edit the kernel.
Add the text single to the end of this line and press ENTER to save the changes.
Press the B button to boot the server to these temporary options to reset the root password.
The server will boot up to the root shell. Type in the command passwd to set the new password. The password would need to be entered twice.
```
# passwd
```
Once this has been completed, reboot the server and verify access to the server using the new password.
```
# reboot 
```
Test the newly reset password once the login screen shows up.

Debian & Ubuntu

Log in to the server via Console option from LayerPanel v2.0 and click Send CtrlAltDel button to reboot the server and access the boot menu.
Once the GRUB boot prompt shows up telling to press any key, perform this action to enter the GRUB prompt. (There will only be a few seconds to press a key to stop the automated booting process if this is not done on time, the server would need to be restarted again)
From the GRUB boot prompt, press the E button to edit the first boot option.
In the GRUB menu, find the kernel line starting with linux /boot/ and add init=/bin/bash at the end of the line.
```
# init=/bin/bash
```
Press CTRL+X or F10 to save the changes and boot the server into single-user mode. Once booted the server will boot into the root prompt.
Type in the command mount -o remount,rw /
```
# mount -o remount,rw /
```
Type in the command passwd to set the new password. The password would need to be entered twice.
```
# passwd
```
Reboot the system: reboot -f.
```
# reboot -f
```
Test the newly reset password once the login screen shows up.

Rocky Linux

Log in to the server via Console option from LayerPanel v2.0 and click Send CtrlAltDel button to reboot the server and access the boot menu.
Once the GRUB boot prompt shows up telling to press any key, perform this action to enter the GRUB prompt. (There will only be a few seconds to press a key to stop the automated booting process if this is not done on time, the server would need to be restarted again)
From the GRUB boot prompt, press the E button to edit the first boot option.
Find the kernel line starting with linux and change ro to rw init=/sysroot/bin/sh.
```
# rw init=/sysroot/bin/sh
```
Press CTRL+X or F10 to save the changes and boot the server into single-user mode.
Access the system with the below command.
```
# :/# chroot /sysroot
```
Type in the command passwd to set the new password. The password would need to be entered twice.
```
# :/# passwd
```
Run the below command to force file-system relabeling.
```
# :/# touch /.autorelabel
```
Reboot the system: reboot -f.
```
# :/# reboot -f
```
Wait for some time, as the relabeling will take a few minutes to get completed. Once this is completed, the server will be restarted once again automatically.
Test the newly reset password once the login screen shows up.

Alternative Method for Rocky Linux

Log in to the server via Console option from LayerPanel v2.0 and click Send CtrlAltDel button to reboot the server and access the boot menu.
Once the GRUB boot prompt shows up telling to press any key, perform this action to enter the GRUB prompt. (There will only be a few seconds to press a key to stop the automated booting process if this is not done on time, the server would need to be restarted again)
From the GRUB boot prompt, press the E button to edit the first boot option.
At the GRUB menu, select the kernel line starting with linux and press END key. This will take you to the end of the line. Here type in rd.break console=tty1.
```
# rd.break console=tty1
```
Press CTRL+X or F10 to save the changes and boot the server into single-user mode.
The server will be booted into the switch-root prompt.
When using rd.break, the system will be directly mounted on /sysroot in read-only mode and it needs to be remounted in read/write mode. The below command helps in this.
```
# mount -o remount,rw /sysroot
```
Switch into a chroot jail using the below command, where /sysroot is treated as the root of the filesystem tree.
```
# chroot /sysroot
```
Type in the command passwd to set the new password. The password would need to be entered twice.
```
# passwd
```
Reboot the server by executing the below command.
```
# :/# reboot -f
```
The server will be rebooted back into the login prompt from where the newly set password can be used to log in to the system.

Fedora

Log in to the server via Console option from LayerPanel v2.0 and click Send CtrlAltDel button to reboot the server and access the boot menu.
Once the GRUB boot prompt shows up telling to press any key, perform this action to enter the GRUB prompt. (There will only be a few seconds to press a key to stop the automated booting process if this is not done on time, the server would need to be restarted again)
From the GRUB boot prompt, press the E button to edit the first boot option.
Find the kernel line starting with linux, linux16 or linuxefi, change ro to rw init=/sysroot/bin/sh.
```
# rw init=/sysroot/bin/sh
```
Press CTRL+X or F10 to save the changes and boot the server into single-user mode.
Remount the hard drive with read-write permission.
```
# mount –o remount,rw /sysroot
```
Access the system with the command: chroot /sysroot and press ENTER.
```
# chroot /sysroot
```
Type in the command passwd to set the new password. The password would need to be entered twice.
```
# passwd
```
Reboot the system: /sbin/reboot -f.
```
# /sbin/reboot -f
```
Test the newly reset password once the login screen shows up.

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