sudo: /etc/sudoers is owned by uid 501, should be 0 not mounting for recovery [duplicate]
You can boot into single user mode by pressing Cmd-S on startup (see OS X: How to start up in single-user or verbose mode for details) which should give you a root shell. Then run
mount -uw /
chown root:wheel /etc/sudoers
chmod 440 /etc/sudoers
reboot
to fix the problem and restart.
You can fix this via AppleScript, without needing to reboot, or even log out & back in, or an existing root shell, or... All you need is a valid administrator password.
Run this command:
osascript -e 'do shell script "chown root:wheel /etc/sudoers; chmod 440 /etc/sudoers; chmod -N /etc/sudoers" with administrator privileges'
...and then authenticate as an administrator when requested.
Explanation: this is a bit indirect. It uses the shell command osascript to run a short AppleScript that uses the do shell script command to run a short shell script. The reason for the shell->AppleScript->shell thing is to use the with administrator privileges option, which has much the same effect as sudo but will work even if /etc/sudoers is completely messed up.
For macOS Mojave, here is what worked for me:
- Start up in recovery mode (Cmd+R during boot up)
- Disk Utilities > Select Macintosh HD, and Mount
- Close Disk Utilities
- Utilities > Terminal
- Type:
chown root:wheel "/Volumes/Macintosh HD/etc/sudoers" - Reboot
You may also need to change the ownership of ts, back in the Terminal:
sudo su
sudo chown -R root:wheel /var/db/sudo/ts/
Yosemite and earlier OSX keeps info on what permissions system files (i.e. files the OS installs) should be. Apple's doc
To restore this use Disk Utility.app.
Select the boot volume (by default called Macintosh HD) on the left hand side.
Click the Verify or Repair Disk Permissions - the latter will reapply the stored permissions.
To edit sudoers in the future I would use visudo which checks that the edit is valid
re the root password you probably have not set it before - the idea of sudo is that you never need to use it and Apple disables root login by default