repairing sudo permissions (creating a bootable installer for El Capitan)

[rickydick]

Hello!
My MBA 2011 running El Capitan has started to have weird behaviour, so I want to do a clan install of El Capitan from a bootable USB drive.
I have the El Capitan installer file, but I cannot create the bootable installer in terminal with:

sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/USBdrive --applicationpath /Applications/Install\ OS\ X\ El\ Capitan.app

I always get the following error:
sudo: unable to stat /etc/sudoers: Permission denied
sudo: no valid sudoers sources found, quitting

I suppose my sudo permissions got corrupted... Anybody can tell me how to repair permissions of sudo?

I know this should be possible using single user mode, but I have no clue as which commands would do that.
I already run ONXY's permission repair, but this apparently does not repair the sudo.

Thanks for your precious help!

 

[rickydick]

Hi everybody,
Just resolved the problem with the help of this article:

Fix sudo: unable to stat /etc/sudoers: Permission denied sudo: no valid sudoers sources found, quitting

Fix sudo: unable to stat /etc/sudoers: Permission denied sudo: no valid sudoers sources found, quitting - fix-sudoer-issue.txt

gist.github.com

Reboot into single user mode (hold Option S while booting until it switches to text mode)

At the single user prompt, type: /sbin/fsck -fy

This checks the filesystem integrity

Then type: /sbin/mount -wu /

This mounts the root filesystem as read/writable.

Next type: /bin/chmod 1775 /

This will correct the permissions for your / directory

Type: /bin/sync

This will make sure the change is written to the filesystem

Type: exit




My sudo is repaired, and my USB drive in about to be prepared