Re: Repair Permissions in Disk Utility prior to OS X 10.11 El Capitan - Reset Home Folder Permissions in Terminal

[Michael Hawkins]

Thanks Ronni for your very clear explanation.  Cheers,
Michael

Sent from my iPhone

> On 4 Oct 2015, at 11:15 AM, Ronni Brown  wrote:
> 
> Hi Michael and any member interested in this subject,
> 
> Michael’s previous questions to the list under the Subject: Re: the spinning 
> beach ball has changed!
> 
>> "Going by how often running "repair permissions" seemed to work for me, does 
>> this mean (a) I was deluded (b) Apple has sorted something out that had 
>> lingered for a long time or (c) software updates are going to be released 
>> every three weeks or so ?"
> 
> 
> To answer your question, I’ll need to explain to you what “Repair 
> Permissions” using Disk Utility in OS X prior to El Capitan repaired. 
> Hopefully below will help answer your previous questions.
> 
> Repair Permissions in Disk Utility - Reset Home Folder Permissions in 
> Terminal  
> 
> Part A of my Reply:
> Repair Permissions in Disk Utility in OS X prior to El Capitan 
> 
> In OS X, each file contains information specifying which users (or parts of 
> the system) can read it, modify it, or execute it. 
> This information is collectively known as permissions. If a file has 
> incorrect permissions, it can cause apps to misbehave in various ways, such 
> as crashing or failing to launch.
> 
> Ordinarily, installers set the correct permissions for the files they 
> install, and the permissions stay that way permanently. However, a poorly 
> written installer can mess up permissions — even for files it did not install 
> — and if you use Unix commands such as chown and chmod, you can accidentally 
> set files’ permissions incorrectly. 
> These sorts of problems occur infrequently, but they do occur.
> 
> The Repair Permissions feature looks for certain software installed using 
> Apple’s installer, which saves files called receipts that list the locations 
> and initial permissions of all the files in a given package. Repair 
> Permissions compares the current permissions to those in the receipts and, if 
> it finds any differences, changes the files back. 
> The command ignores software installed in other ways (using a different 
> installer or drag-and-drop installation, for instance) and knows nothing 
> about permission changes you may have made deliberately.
> 
> Permissions don’t go out of whack all by themselves; you (or software you 
> install) must do something to change them. 
> 
> Are all files affected by Repair Disk Permissions?
> 
> No. As you may have inferred from the above description, only those files 
> installed using OS X’s Installer utility and whose installation packages 
> leave behind a proper receipt in /Library/Receipts are affected by the Repair 
> Disk Permissions function. 
> 
> This means that most of the files affected by the Repair Disk Permissions 
> function are system-level files, application files, or system add-ons—not 
> applications installed by drag-and-drop, and not your documents or other 
> user-level files.
> Repairing permissions is mainly a tool for fixing 'permissions-related' 
> problems with OS-level Apple software .
> But beyond that, only certain receipts are referenced, all of them associated 
> with OS-X-related software.
> 
> Although some might argue that restricting the Repair Disk Permissions 
> function to Apple-installed software is a limitation, it’s also good 
> security. If third-party receipts were used as references when repairing 
> permissions, a piece of malware could leave behind a receipt designed to 
> maliciously change permissions on system-level files—for example, to assign 
> more-accessible permissions on normally secure files and directories. This 
> could be a major security risk.
> 
> But starting in OS X 10.11 El Capitan, the Repair Permissions feature is gone 
> from Disk Utility entirely.
> Beginning with OS X El Capitan, system file permissions are automatically 
> protected. 
> It's no longer necessary to verify or repair permissions with Disk Utility.
>  Instead, permissions are repaired automatically when you install software 
> using Apple’s installer.
> —
> Part B of my Reply:
> Does repairing permissions affect third-party application files?
> 
> Apple’s description of the Repair Disk Permissions function seems to imply 
> that any software, including third-party software, installed using Installer 
> and accompanied by a receipt in /Library/Receipts is affected by repairing 
> permissions. 
> However, we know from my previous reply above that this isn’t the case. The 
> only third-party software affected by repairing permissions is software 
> included with Mac OS X and installed by the Mac OS X Installer.
> 
> Reset Home Folder Permissions in Terminal
> 
> Disk Utility only checks a limited subset of files, and it won’t repair 
> anything within your Home folder. There is a slightly more convoluted way to 
> fix permissions issues there.
> Why might you want to do this, you ask? The most common scenario is that 
> something’s 

Repair Permissions in Disk Utility prior to OS X 10.11 El Capitan - Reset Home Folder Permissions in Terminal

[Ronni Brown]

Hi Michael and any member interested in this subject,

Michael’s previous questions to the list under the Subject: Re: the spinning 
beach ball has changed!

> "Going by how often running "repair permissions" seemed to work for me, does 
> this mean (a) I was deluded (b) Apple has sorted something out that had 
> lingered for a long time or (c) software updates are going to be released 
> every three weeks or so ?"


To answer your question, I’ll need to explain to you what “Repair Permissions” 
using Disk Utility in OS X prior to El Capitan repaired. 
Hopefully below will help answer your previous questions.

Repair Permissions in Disk Utility - Reset Home Folder Permissions in Terminal  

Part A of my Reply:
Repair Permissions in Disk Utility in OS X prior to El Capitan 

In OS X, each file contains information specifying which users (or parts of the 
system) can read it, modify it, or execute it. 
This information is collectively known as permissions. If a file has incorrect 
permissions, it can cause apps to misbehave in various ways, such as crashing 
or failing to launch.

Ordinarily, installers set the correct permissions for the files they install, 
and the permissions stay that way permanently. However, a poorly written 
installer can mess up permissions — even for files it did not install — and if 
you use Unix commands such as chown and chmod, you can accidentally set files’ 
permissions incorrectly. 
These sorts of problems occur infrequently, but they do occur.

The Repair Permissions feature looks for certain software installed using 
Apple’s installer, which saves files called receipts that list the locations 
and initial permissions of all the files in a given package. Repair Permissions 
compares the current permissions to those in the receipts and, if it finds any 
differences, changes the files back. 
The command ignores software installed in other ways (using a different 
installer or drag-and-drop installation, for instance) and knows nothing about 
permission changes you may have made deliberately.

Permissions don’t go out of whack all by themselves; you (or software you 
install) must do something to change them. 

Are all files affected by Repair Disk Permissions?

No. As you may have inferred from the above description, only those files 
installed using OS X’s Installer utility and whose installation packages leave 
behind a proper receipt in /Library/Receipts are affected by the Repair Disk 
Permissions function. 

This means that most of the files affected by the Repair Disk Permissions 
function are system-level files, application files, or system add-ons—not 
applications installed by drag-and-drop, and not your documents or other 
user-level files.
Repairing permissions is mainly a tool for fixing 'permissions-related' 
problems with OS-level Apple software .
But beyond that, only certain receipts are referenced, all of them associated 
with OS-X-related software.

Although some might argue that restricting the Repair Disk Permissions function 
to Apple-installed software is a limitation, it’s also good security. If 
third-party receipts were used as references when repairing permissions, a 
piece of malware could leave behind a receipt designed to maliciously change 
permissions on system-level files—for example, to assign more-accessible 
permissions on normally secure files and directories. This could be a major 
security risk.

But starting in OS X 10.11 El Capitan, the Repair Permissions feature is gone 
from Disk Utility entirely.
Beginning with OS X El Capitan, system file permissions are automatically 
protected. 
It's no longer necessary to verify or repair permissions with Disk Utility.
 Instead, permissions are repaired automatically when you install software 
using Apple’s installer.
—
Part B of my Reply:
Does repairing permissions affect third-party application files?

Apple’s description of the Repair Disk Permissions function seems to imply that 
any software, including third-party software, installed using Installer and 
accompanied by a receipt in /Library/Receipts is affected by repairing 
permissions. 
However, we know from my previous reply above that this isn’t the case. The 
only third-party software affected by repairing permissions is software 
included with Mac OS X and installed by the Mac OS X Installer.

Reset Home Folder Permissions in Terminal

Disk Utility only checks a limited subset of files, and it won’t repair 
anything within your Home folder. There is a slightly more convoluted way to 
fix permissions issues there.
Why might you want to do this, you ask? The most common scenario is that 
something’s gone wonky with files or folders in your Home folder; you try to 
save something to your Desktop, say, and your Mac tells you that you don’t have 
permission to do so.

Reset ‘Home Folder Permissions’ in Mountain Lion & Mavericks & Yosemite

You can reset your Home Folder Permissions from the Recovery HD using the Reset 
Password application.