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dwlz
Asked: 2010-10-30 20:07:21 +0800 CST

How do I restore access to sudo after chmod 750'ing /usr?

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In a stroke of sheer brilliance, I just chmod 750'ed my /usr and /etc directory on my VPS. Now, whenever I run sudo, I get -bash: sudo: command not found. Is there any way you can think of for me to restore access?

I tried to scp sudo over to the computer, but got a 

bash: /etc/bash.bashrc: Permission denied
bash: scp: command not found
lost connection

If you can figure this one out, you're a genius.

ubuntu amazon-ec2 ssh

4 Answers

  1. do su root instead of sudo

    since su is often in /bin, you should not be impacted by your mistake

    of course this requires you to know the root passwd...

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  2. Best Answer

    Can you get a console to the machine? If so, reboot into recovery mode or some such thing (add kernel opts init=/bin/sh will drop a root shell). Then you'll be root, and can chmod as needed.

    Other options include doing a bare metal restore (you've got a backup, right?) (If you don't you might be able to cobble something together from whatever is in /bin)

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  3. Some VPS companies have web console access enabled. Check also that out.

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  4. Perhaps use netcat to transfer sudo over? At least on my Ubuntu (karmic) machine netcat is in /bin.

    Unfortunately having the file won't help much since you'll need it to be setuid root for it to work and you won't have the permissions to make it so.

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