How to Reset Root Passwords on RHEL 7 and CentOS 7 Linux SystemsIf you have forgotten your root password on a RHEL 7 server or a CentOS 7 server, you can reset your root password as long as you have access to the GRUB 2 bootloader. (The following example was performed on a RHEL 7.5 server)
To access the GRUB 2 bootloader, boot your system and wait for the GRUB 2 menu to appear:
Boot System and wait for GRUB 2 menuBoot your system and wait until the GRUB2 menu appears. On some systems you may need to press the "Escape" key to access the GRUB 2 menu.
Highlight OS EntryHighlight your Operating System and then press "e" to edit.
Find line beginning linux
Find the line beginning with linux. In this example the line begins linux16.
Manually Edit Line
Using the arrow keys and the delete key, manually delete the following entries rhgb and quiet from the line.
Next, append the following statement to the end of the line init=/bin/sh
Don't worry if your command is spread across more than one line. A continuation character "\ will be inserted automatically.
Ctrl +X to reboot using the specified options
To reboot your system now using the options specified, press the keys Ctrl +X
Once the system has re-booted, you will be presented with a shell prompt without having to enter any user name or password information
At this command prompt you will need to enter the following commands below:
Load Local SELinux Policy
Load the installed SELinux policy: /usr/sbin/load_policy -i
Remount "/" Filesystem in Read/Write mode
Remount the "/" root filesystem in Read/Write mode: mount -o remount,rw /
Issue passwd Command
Issue the passwd command to reset the root account password: passwd
Remount "/" Filesystem as Read Only
Remount the "/" root filesystem in Read Only mode: mount -o remount,ro /
Now reboot the system
You can now reboot the system. You can issue the command "exec /sbin/init 6" to reboot.
Once your system is backup, you should be able to login with the new "root" password.
Login with New Password
You should now have arrived at the login screen. Here you will be able to login with your root account using your new password. (You may need to login as a normal user then "su" to root depending on your system set-up)