I will start from the beginning.

I was a noob and ran a really bad command in Ubuntu and now I can't do anything with sudo.

I ran:

sudo chmod 644 /

I was instructed to boot from a liveCD or liveUSB. I chose USB because I still have the one from when I installed it.

I was told to run this from within the booted liveUSB:

sudo chmod 755 / 

And it should be fixed. Well it's not. My best guess is because I am changing the permissions on the root directory of the USB and not the root directory of my laptop.

What am I missing here? How can I fix this?


You are right, if you did that, you changed the mode of / of the live-system, but you want to change the mode of / of your root-partition on your hard-disk, so you first need to mount your hard-disk.

Assuming your root-partition is /dev/sda2, enter

mount /dev/sda2 /mnt

to mount your root-partition to /mnt. Then change to that mount-point and change the permissions:

cd /mnt && chmod 755 .

If you are still experiencing problems, a more detailed explanation would be helpful.

  • Is there anyway to get a list of mountable drives? I don't remember what my partition is. – wesleywmd Dec 5 '14 at 17:06
  • I'm getting an error : mount: you must specify the file system type – wesleywmd Dec 5 '14 at 17:11
  • 1
    Use fdisk -l to see all attached devices and partitions. Using this I determined I need to mount sda5 not sda2. – wesleywmd Dec 5 '14 at 18:17

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.