I changed /etc/sudoers file rights to 0740, because I wanted to edit it as root. I could edit it.
What is happening now is that I can't change it back to 0440. I can't sudo anymore. I always get this error message :
sudo: /etc/sudoers is mode 0740, should be 0440 sudo: no valid sudoers sources found, quitting sudo: unable to initialize policy plugin
Does somebody know how to get back to normal ?