How can I fix broken sudo - sudo: parse error in /etc/sudoers near line 23? [duplicate]

I am getting this error:

sudo: parse error in /etc/sudoers near line 23
sudo: no valid sudoers sources found, quitting
sudo: unable to initialize policy plugin

I was trying to disable password authentication so I don't have to type password every time I want to install something, but I probably changed it in a not very good way. I am a newbie to Ubuntu, I got sick of Windows :)

So far I've found some people suggesting booting in single user mode, but I'm afraid of messing things up more.

How can I fix this error?

Solution 1:

Fixing this is dead simple, and it is answered elsewhere on askubuntu.

Short answer, use:

pkexec editor_of_choice

Solution 2:

Hold Shift immediately while booting so that you get the GRUB screen. Select the recovery mode. Choose to drop to a root terminal. Run mount -n -o remount,rw / and then visudo. It'll let you fix your problems with the file and save. It won't let you save a malformed file.

Solution 3:

Folowing solution is for remote servers, it works!

http://ubuntuforums.org/showthread.php?t=2036382&p=12144840#post12144840

then just use visudo to add wheel, etc

1. Rename your current file

   mv /etc/sudoers{,.bak}

2. Create a new one vi /etc/sudoers with the following basic content:

   # /etc/sudoers
   #
   # This file MUST be edited with the 'visudo' command as root.
   #
   # See the man page for details on how to write a sudoers file.
   # Defaults    env_reset
   # Host alias specification
   # User alias specification
   # Cmnd alias specification
   # User privilege specification
   root    ALL=(ALL) ALL
   # Allow members of group sudo to execute any command after they have
   # provided their password
   # (Note that later entries override this, so you might need to move
   # it further down)
   %sudo ALL=(ALL) ALL
   #
   #includedir /etc/sudoers.d
   # Members of the admin group may gain root privileges
   %admin ALL=(ALL) ALL
   

3. Run visudo and add your custom stuff.

Solution 4:

If u messed up your sudoers file.You'll need to:

• Reboot into recovery mode (hit escape during boot, choose the recovery mode option on the grub screen)
• Choose the 'Enable networking' option (if you don't your filesystem will be mounted as read-only. who knew)
• Chosee the 'Drop to root shell' option
• run visudo, fix your file
• Reboot with normal grub option

source :- http://mario.net.au/content/recover-etcsudoers-ubuntu-1204