I used the command "chmod 700 / usr", now what? [closed]

If you took security precautions when you installed your operating system, you must have changed or created a password for the root user. Since you have done this, it should still be possible to issue the command su root that will log you as root without using /usr/bin/sudo , which should work.

However, if this is not the case, you still have two other options. You can try logging in as Single User Mode in>> (which will log you into a shell directly as root ) and from there you can undo this "bullshit."

If none of this works, another computer or other disk / operating system (in this case, Linux) will be needed to help you. You will need to add the affected disk to the target system, boot and log into the healthy and functional operating system, and from there you will use the chroot tool to change the base path of your shell into the partition where your installation Ubuntu with problems is.

This will allow you to correct the permissions (since sudo will use the permissions of the shell it was launched on, so you do not need to be root of your Ubuntu). It also allows you to change the password of your root (as a precaution) in case something else goes wrong. You can learn more about chroot by # . It's the Gentoo installation documentation, but it's in Portuguese and can give you some instructions on how to do it.

Remember that if you choose the last method, once you access your partition from the other computer, I strongly recommend BACK UP YOUR PERSONAL DATA , because if you make mistakes in this step you can cause irreparable damage to your data.