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Long story short, while learning bash scripting etc, I erroneously ran chmod -R 770 /bin (please don't ask why, this is already quite embarrassing as is).

The issue that made me realize the horrible mistake was a denied permission running /bin/bash when logging in as user (resulting in a closed SSH connection), and after trying many other solutions found googling, I checked .bash_history to find out the comic mistake.

Anyways, is there any way at all to get permissions back to defaults for folder and files? (other than reinstalling the os)

I have a backup of the whole SD (I'm on a headless RasPi running Minibian) not older than 3 days, but I'm not quite sure rolling back the previous version would actually change any permission. Are these details stored in the folder itself, or in some sort of a registry?

Also. Why is it that, despite being the permissions rwx on the user as well as the root, the scripts aren't executed?

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    How did you make the backup? – muru Dec 11 '15 at 19:20
  • dd from /sd to .img – nxet Dec 11 '15 at 19:21
  • It would be simpler if you can boot to a live USB and mount the Pi and the backup image. Can you do that? Which distro are you using? Please edit your question to add clarifications. – muru Dec 11 '15 at 19:24
  • (added above) I'm running Minibian. And what do you mean by mounting the Pi? In any case, in this very moment the Pi is the only Linux machine I can use, therefore it would be best for me to find a solution working directly on the Pi logged in as root. – nxet Dec 11 '15 at 19:29
  • just to be clear, did you mean to guide me through a procedure like the following? superuser.com/questions/132891/… – nxet Dec 11 '15 at 19:33
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For a starter, chmod -R 555 /bin will get you up and running.

Then chmod 4755 /bin/ping6 /bin/su /bin/mount /bin/ping /bin/umount will get your setuid scripts working.

If you didn't mess up /usr/bin, your sudo should be okay but if not run chmod 4111 /usr/bin/sudo.

There is more that should be fixed but this would be the start of a recovery procedure if overwriting that whole directory is not an option.

  • simple overwriting can be an option then? – nxet Dec 11 '15 at 20:19
  • Should be, if you have a backup. Just be sure you copy from the backup (a) as root, and (b) with a "preserve permissions and owner" flag set. (I often use rsync rather than cp because it is considerably faster for many cases and it is more versatile.) – Wildcard Dec 12 '15 at 0:42

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