Changing ownership of ‘/usr/bin/’: Operation not permitted

Question

I have just made a huge mistake by changing the owner of my /usr/bin from root to an ordinary user. Whenever i try to execute $sudo chown root /usr/bin this gives me :

chown: changing ownership of ‘/usr/bin/’: Operation not permitted

I have read many topics talking about this issue, which most of them give a solution in case you have already a backup image of your OS. Unfortunately I don't have any backup. Is there any solution then other than reinstalling Ubuntu from scratch.

Answer 1

Solution:- Get in to Ubuntu Recovery Console Start your computer and press and hold SHIFT key while booting. It will take you to the grub loader page as shown in image – 1.

Image 1

Select and enter Advanced options for Ubuntu and from there select the kernel named as recovery mode as shown in image – 2.

Image 2

select root – drop to root shell prompt as shown in image – 3

Image 3

Now the file system is read only to Remount to Read Write run below command

# mount -o remount,rw /

mount –all

then need to change the ownership for sudo

# chown root:root /usr/bin/sudo

give permisson for sudo

# chmod 4755 /usr/bin/sudo

it’s done … let’s see by restarting the machine

# shutdown -r now

You should have your Sudo back by now....

Answer 2

If you can't gain root with plain "su" because you don't know the password or none has been set, then you have to reboot into a root shell. When you see the GRUB boot menu, press "e" to edit the kernel command lines, and append "init=/bin/sh" - then it will dump you into a single-user root shell instead of the normal boot process. Here you may have to remount the root file system read/write:

# mount / -n -w -o remount

Then you need to undo the damage from earlier:

# chown -R root /usr/bin

Then finally remount the file system read-only, sync and reboot:

# mount / -n -r -o remount
# sync
# reboot -f