Changed permissions now Mac wont start

[mcregal]

Big thanks

Thanks DJ-KATCHEY! This worked like a champ!

 

[ccpi]

Fix for Yosemite

Please can someone help. I am another victim of stupidity and apple’s bug..
I changed my permissions, adding myself as read write and including the change to all enclosed folders.
Now my system just hangs on re-start with the apple logo on grey screen and the turning wheel.
I have tried booting into single user mode and tried the following strings, but none seems to work.
I do not know DOS and am quite ignorant when it comes to Command prompt strings and commands but will follow letter by letter any advice.
Oh .. to make matters worse I am stuck at sea and do not have my startup CD !!! STUPID!!
I have a MacBook running 10.6


Boot into single user mode and type
sudo chmod 755
The result is
sudo: / private/etc/sudoers is in mode 0664, should be 0440”
:/root# sendamail ; warning: valid_hostname:empty hostname
Sendmail : fatal : unable to use my own hostname

The other solution I tried, also in single user mode is

Cd /Volumes
:Volumes root# chmod 755 Richard\’s\ Notebook/ (this string is achieved by typing the first letters of my drive and TAB)
The result is just “:Volumes root#”

I also try
chmod 755 Richard’s Notebook/ .. result is “>”

Please help .. I really really need my email..

I'm using Yosemite. I did the same silly thing (hit "apply to enclosed items" after changing permissions) then my mac wouldn't startup. I reinstalled OS X Yosemite which fixed it.
----- Instructions for reinstall from Apple:
*Use the built-in recovery disk to reinstall OS X while keeping your files and user settings intact.

*Important: You must be connected to the Internet to reinstall OS X.
In the menu bar, choose Apple menu > Restart. Once your Mac restarts (and the gray screen appears), hold down the Command (⌘) and R keys.

*Select Reinstall OS X, then click Continue.

*Follow the onscreen instructions. In the pane where you select a disk, select your current OS X disk (in most cases, it’s the only one available).

 

[newyorknight]

Big thanks

Thanks DJ-KATCHEY! You are a GOD!!

I had changed permissions on all my partitions including Mac HD to Everyone / No Access, so that other users could not get into any of my files on that drive, including desktop.
Big mistake!!

I get VERY nervous going into command lines, but your instructions worked!! Thank you for saving me DAYS worth of aggra and from taking my computer into the store.

Thank you Thank you!!

 

[Cinephobia]

I accidentally changed the permissions on a disk

If the disk in question is your Mac OS X startup disk and your computer stops starting up at the blue screen, restart with the Command and S keys held down, and enter the following commands:

mount -uw /
chown root /
chmod 1775 /
exit

Enjoy!!!!
Works 100%[/B]

I just spent 48 hours banging my head against a wall trying to copy files using the command line with the drive not booting up. But I couldn't even run the diskutil function. I was trying to trouble shoot errors within errors within errors. Multiple convos with Apple senior level guys proved useless, a wasted trip to the Apple repair store and I was ready to pack it up and take it somewhere else....when I stumbled upon these three lines.

Hoping it would allow me to run the DiskUtil feature, I entered the code....computer powered down....and powered up working completely fine!

I can't believe it.

Thank you!