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this post was submitted on 21 Nov 2023
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Linux
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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
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sudo chmod -R 777 /Edit: don't do this, it will allow everyone and everything to read and modify all files of all mounted filesystems, this includes your personal files, system wide passwords, config files, everything and might break the whole system as not all files are meant to have these permissions, e.g. mapped hardware settings or your ssh key store.
sudocomes with immense power, do not, under any circumstances, enter commands you found on the internet without an intense look about what they do and what their implications could be. Neversudoordoas, etc., without a strong and valid reason.For anyone that didn't recognise this as a joke, do not do this!
Oh. Ok. Should I undo it then?
Yeah just hit Ctrl + Z and you should be fine
Yup, this will pretty much destroy your system.
Actually curious how though - I mean won't it just let all programs/users access everything? Or do some system stuff rely on permissions for certain behavior?
SSH will definitely break, I've had this issue before. If your private key in the .ssh dir is too open, ssh won't let you use it.
Theoretically yes, but yes, in that order.
I've worked with Linux for decades at this point and I'm still not 100% sure exactly what breaks; it's a mistake you make once, if at all, and you'll only get a little way into even trying to figure out how to fix things before you throw your hands up in disgust and reinstall / restore the OS (or whatever subdir was affected).
If I was to hazard a guess, it's the kernel itself that balks, but there are other, almost as fundamental things (lib*.so files and the like) that may also be deliberately fussy.
I think it's systemd not the kernel. If only Linux had "repair permissions" like vintage MacOS.
Recursive
chmod(orchown) has been breaking things since before systemd was a thing, so even if systemd is now responsible for stopping things from working, it can't have been that previously, especially at the time I might have done something silly.As for repairing permissions only, I suppose it would be possible, assuming the system still works (or can somehow be encouraged to do so) to copy only the permissions (or at least infer them) from a backup or something rather than the whole files.
Probably init before that then. I don't think the kernel cares unless explicitly told to care, I've seen some embedded Linux with interesting permissions.
You don't typically have permissions "become defective" or need them to be "repaired" in a Linux system. Nearly all system files, with their permissions, are included in packages. Everything else should be considered user data.
If you logged in as root and did something dumb, you could attempt to fix the permissions by reinstating packages.
I actually don't know how many programs do this, but several check that file permissions are correct or refuse to work. Sudo and ash are 2 of them. I could see /etc/shadow being readable and writable by everyone being a problem too, but I don't know.
Some things refuse to run with too broad permissions
Edit removed it. What was it?
The
chmodyou can still seethe
777stands for 'lucky jackpot number', as in 'youre lucky if you dont break your entire system'well,
666would '-_-'This is so useful! Now I can just run:
rm -rf /Without the sudo!
--no-preserve-rootThat's all true, except when I send you a command. You can totally trust me and just run it.
remove the French language pack, frees up space
I set 777 to my whole file system on a install of Ubuntu back in the day and it does indeed fuck the install in lovely ways. I didn't bother attempting recovery. Nice learning experience.
@drdiddlybadger @neonred I've had results with chmod -r +x /
Timeshift: hold my beertfs
Challenge time.
Better than 666, which I did once 20 years ago