Repair Permission


Do this before upgrade your OS X: better put a little effort than sorry later

Understand who is the owner of your OS (operating system) on all the computers: Unix, Linux, Mac, _except_ Windows.

  • Your computer is owned by root account instead of user: you
  • In order to protect OS, user account has limited access (this explains why attacking Windows is easier than Unix based OSes such as Linux and Mac OS)
    • Login as root account is prohibited even to a Professional computer engineers. If and when an expert user needs root access, the sudo command will grant a temporary access.

As you understand now, access privilege is very important. Unfortunately this access privileges may be damaged time to time. A few reasons as follow:

  • A 3rd party application installer was written badly
  • Incorrect permission, which did not cause any issue, causes issues when and/or after OS update/upgrade

Repairing Permission (access privileges) is a responsibility to all the professional computer users

Again, if you upgrade OS without checking/fixing Permission could cause troubles down the load.

El Capitan user ⇨

Starting up into Recovery Mode

  1. Turn your Mac power on, or select Restart from a running Mac
  2. Before you hear the startup chime (as know in the movie "Wall-E"), hold ⌘+R
  3. You can take your fingers off when the screen becomes gray
  4. Wait until OS X Utility window appears

If you didn't see OS X Utility window, you held ⌘+R too late and you need to start over, or your Recovery Volume is damaged.

When OS X Utility screen appears, double click on Disk Utility

Select your boot volume then click on [Repair Permission]

Note: always run twice. If error message(s) persist, make a note of it then google later. In most cases, the errors persists after 2nd run is not critical.

After running [Repair Permission] twice, it is advised to reset ACL (Access Control List) before OS X upgrade. This will clean up most of the access privilege issue on your HOME folder. This is critical when you use Migration Assistant to move your HOME data.

Exit Disk Utility by ⌘+Q. You are back to OS X Utility window.

Click on Utility Menu then select/open Terminal.

When Terminal is open, type


then hit [return] key

Select your OS X boot volume then click on [Reset] button. This may take a while. Have a break.

Exit Reset screen by ⌘ + Q. You may need to press ⌘ + Q again to dismiss Terminal. Then exit OS X Utility by pressing⌘ + Q again. Follow the Restart instruction to restart then log in as usual. Now you are ready for OS X upgrade.


Running this procedure after OS X upgrade and update is also recommended, while ACL Reset is maybe needed only before OS X upgrade.