Sudo – Fix ‘Permission Denied’ for All Sudo Commands


I just typed "sudo chmod 770 ." on my /usr/bin directory by mistake

[acc]:/usr/bin$ sudo chmod 770 .

Now every time i run a sudo command I get a "Permission denied" error

[acc]~$ sudo
bash: /usr/bin/sudo: Permission denied

When I open a new terminal, i get: "bash: groups: command not found"

Please help me resolve this… 🙁

Best Answer

You should boot from a LiveCD then do the following:

  1. Mount your Ubuntu installation by clicking on the device's icon in the file manager.
  2. Open a terminal and cd into the /usr/bin folder of that installation you mounted from above.
  3. Run this command to give all users execute permissions

    sudo chmod -R a+x .
  4. Run this command to give all users read permissions

    sudo chmod -R a+r .
  5. Run this command to remove all users (except root's) write permissions

    sudo chmod -R o-w .
  6. Reboot and see if it works.
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