Anyone know what this command does?: chmod -R 777 / (trying to fix the blue-screen)

Discussion in 'macOS' started by senorfrog97, Sep 9, 2009.

  1. senorfrog97 macrumors regular

    Jan 19, 2008
    So the code is: chmod -R 777 /

    I was following 'instructions' from this random thread I found trying to fix my g/f's macbook running 10.5.8 - it just sits at the blue screen at start up.


    I followed the instructions in post #8. Is that a legit fix or is that guy messing with people and I screwed up her computer?

    Anyway it didn't work - still a blue screen - guess I'll just tell her to go see a genius.
  2. Nugget macrumors 68000


    Nov 24, 2002
    Houston Texas USA
    That command is not harmful, per se, but it's a really bad thing to do. It sets every single file and directory on your computer as executable and world-writable. Sort of like leaving all your doors and windows wide open because the lock is sticky. I doubt the guy suggesting that fix is intentionally messing with you, he's probably just ignorant and misguided.

    A "repair permissions" afterwards (assuming it fixes the problem, which it probably won't) gets you sort of back to normal, but not really.

    I'd keep looking for a solution that doesn't involve that command.

    I suggest trying a verbose boot by holding command-V when you power up. It'll spit a pile of text at you that you don't understand, but googling the consequent errors or warnings might get you closer to a fix or minimally might help us lead you to a workable solution.
  3. electroshock macrumors 6502a


    Sep 7, 2009
    Let's just put it this way: that guy won't be applying for a Genius Bar position anytime soon. I don't think he was intentionally messing around with people, but simply doing that step out of ignorance of its full impact.

    That's just an incredibly bad thing to do for so many reasons. For one thing, it may break apps and potentially various bits of OS functionality. For another, it opens yourself up to being hacked badly because an attacker can now read and write to every single file on the system including the password files.

    Worse yet is there's no easy way to undo the damage done by that command short of a total reinstallation/restore. Repair permissions only works on files/dirs registered with OS X, but not with 'all the rest'... So you really do have to reinstall/restore the OS to get back to a sane setup, permissions-wise.

    Hopefully she had an external drive with Time Machine backups on it as that'll make it much easier to restore with minimal downtime and no data loss. (Of note: if she does, restore to the last backup BEFORE the chmod was done.)
  4. senorfrog97 thread starter macrumors regular

    Jan 19, 2008
    welp, I guess a fresh install is in her near future. Sad thing is she just did one not too long ago.
  5. iShater macrumors 604


    Aug 13, 2002
    It might help her and you to know when this issue started happening and if she recalls anything specific. Battery died and system went off without shutting down properly? a new device and drivers installed? new memory? something connected to the machine? etc.
  6. old-wiz macrumors G3

    Mar 26, 2008
    West Suburban Boston Ma
    I spent 20+ years in the *NIX kernel and I/O programming world, and I shudder at the things people try to do with terminal and *NIX commands. I learned the hard way long ago not to fool around if you are not really sure what you are doing.

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