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Amul Agrawal
Asked: 2019-11-29 00:37:42 +0800 CST

Can't login after entering correct username and password

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I wanted to change the name before hostname on my Ubuntu terminal (the x in x@y ) To do so I replaced old x in /etc/passwd and /etc/shadow with newname

Now when I am trying to open Ubuntu, its not opening up; it is redirecting me to lock screen

username 18.04

2 Answers

  1. Best Answer

    That's because a username mustn't be change manually (it's not about just changing username inside /etc/passwd and /etc/shadow files); the /home directory wasn't created, so it didn't find where it can login, and finally return to the login screen in order to say at user that he must fix this issue. Here are differents ways to fix that :

    • Connect using tty console :

      1. use the shortcut Ctrl + Alt + F1 to open the tty terminal
      2. try to login -> if it didn't work, try login with root access
      3. revert change in /etc/passwd and /etc/shadow files
      4. after revert are effected, use sudo usermod -l newUsername oldUsername command to change the old username oldUsername with a new one newUsername everywhere needed
      5. logout / reboot, you can return to GUI using Ctrl + Alt + F7

    • If you can't connect to a login using the tty console

      1. reboot your computer and start Ubuntu in recovery mode (or command line mode don't know exactly how it is named)
      2. revert change in /etc/passwd and /etc/shadow files
      3. after revert are effected, use sudo usermod -l newUsername oldUsername command to change the old username oldUsername with a new one newUsername everywhere needed
      4. reboot your computer

    • If no one of these methods works, then you can try to restore username by using a live session

      1. use this following commands to mount your partition :

        sudo fdisk -l    ###find the partition which contains your data

sudo mount /dev/sdaN /mnt  ####N is the partition number (can be sdbN, sdcN too)
sudo mount --bind /dev /mnt/dev
sudo mount --bind /sys /mnt/sys
sudo mount --bind /run  /mnt/run
sudo mount --bind /proc /mnt/proc
sudo chroot /mnt           ####after this command, you re inside your previous Ubuntu partition
      2. revert change in /etc/passwd and /etc/shadow files
      3. after revert are effected, use sudo usermod -l newUsername oldUsername command to change the old username oldUsername with a new one newUsername everywhere needed
      4. reboot your computer

    If no one of these methods works (I really doubt), I couldn't help more

    • 1

  2. Both /etc/passwd and /etc/shadow are not meant to be edited manually / with a text editor.

    This won't help you much, but in order to change your username you should have used the usermod command.

    I can think of two possible solutions:

    1. If you have another user on your system, log in, and revert the changes you did on both mentioned files.

    2. Use a bootable medium, like an USB stick or a CD-ROM with Linux, boot your PC and mount the hard drive of your installed Linux. Then revert the changes.

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