title: Sudo not working - "sudo: effective uid is not 0, is sudo installed setuid root?"
body: <p>I have been trying to allow access to the normal user of an EC2 amazon server ('ec2-user') to a certain library. </p>
  
  <p>I did: "sudo chown -R ec2-user /usr" which I realize now had been a fatal mistake. It worked, but sudo is gone. If I try to use sudo I get: "sudo: effective uid is not 0, is sudo installed setuid root?"</p>
  
  <p>I tried "chmod u+s /usr" like it is suggested in another answer. It does not solve the issue. </p>
  
  <p>I guess that there is something basic I am missing. Forgive my newb ignorance.</p>