sudo chmod -R 755 * accidentaly run in /, what are the options?

Question

I have many programs installed, I want to keep my history, and so on and so on.. What can I do to save the situation? Thank you.

Answer 1

You've just found the great powers of being root and how easy it is to screw up your whole system!

I would recommend reinstalling the complete system, because, I can't agree more to what Gilles said in a similar question:

Can it be fixed? Sure. Faster than reinstalling? Probably not.

So, as this is not easy to fix yourself by hands within reasonable time and effort. And if you try, you'll notice a lot of stuff will break: sudo, setuid/setgid binaries, etc.

General steps for a reinstallation:

1. Back up your data, e.g. /home/username.
2. Back up configuration files: /etc
3. Get a list of manually installed packages, which allows you to reinstall them quickly in the new installation.
4. Restore the configuration files selectively. Don't bluntly restore complete /etc as that will break stuff. Only restore files you actually touched yourself.
5. Restore your data.

Done.

I'm looking forward to the time that we have Btrfs as the default file system and we can restore our complete system by simply reverting to a snapshot.

Answer 2

For changing permissions only for folders (directories), recursively, you can use:

sudo find ./ -type d -exec chmod 755 {} \;

For changing permissions only for files, recursively, you can use:

sudo find ./ -type f -exec chmod 640 {} \;

Considering you run the command with 755, you only need to run the command for the files.

Be aware that these commands run in the folder you are in (./).