Ubuntu – Reset root password of a VM

passwordsrootUbuntu

I removed (distrattament) my "sudo" user from sudo group user, I can't use root because I don't know a password for root.

I have an Ubuntu virtual machine and when I open Recovery Menu is limited read-only menu.
If I select "root Drop to root shell prompt"
the message is "Give root password for maintenance" … but I don't know the root password.

How can I reset root password?

Best Answer

To recover the root password, you will need to boot into single user mode. In many distrobutions there is a drop down option to let you select at the boot loader. If you are using GRUB, you can select the version of the OS kernel you would like to boot, hit the "edit" key (e I believe), and then append the word "single" to the end of the kernel parameters string. You can find Ubuntu specific instructions here.

Once you have booted into single user mode, you should see a prompt like this:

sh#

To reset the root password, type:

passwd root

At this point you will be prompted to enter a new password and to confirm the password. You can also modify the /etc/sudoers file to add your user back to the sudoers group.

Related Solutions

How to restore sudo privilege with Linux live CD

You'll have to boot into recovery mode to gain root (system-wide) access in order to repair

If you have a single-boot (Ubuntu is the only operating system on your computer), to get the boot menu to show, you have to hold down the Shift key during bootup.

From the boot menu, select recovery mode

After you select recovery mode and wait for all the boot-up processes to finish, you'll be presented with a few options. In this case, you want the Drop to root shell prompt option.

/etc/group is the file that defines the groups on the system

You can then use adduser username admin to readd your user to the admin group.

Alternatively you can use the vigr command to edit the /etc/group file safely

format example;

group-name:x:group-number:user1,user2
admin:x:110:username

Linux – recovery of password for root in Ubuntu 12.10

Ubuntu, by default, has no password for the user root.

If you locked yourself out of your system,

select "recovery mode" in the grub boot menu, when starting your machine. If you don't see a boot menu, you may need to press Shift during a time window of a few seconds after BIOS stage.

This gives you root access and the power to grant your regular user account its administrative privileges.
Enable write access on /¹.
```
mount -o remount,rw /
```
Add admin to the groups of your account.
```
usermod -a -G admin [account name]
```
Reboot and everything should be back to normal.

¹ I'm not sure whether the recovery mode of Ubuntu 12.10 mounts the root file system or just the initramfs.

Best Answer

Related Solutions

How to restore sudo privilege with Linux live CD

Linux – recovery of password for root in Ubuntu 12.10

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