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#28265 - 03/01/14 02:32 PM Disk Permissions
HappyDog Offline


Registered: 08/20/09
After repairing disk permissions three times in immediate succession, there is still a long list of repaired items when it's finished, most beginning with "ACL found but not expected," with many of these in iTunes.

Any ideas on what's happening? I was expecting an empty box when all were repaired.

I have heard it said the Disk Permissions is useless. Yes? No?

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#28266 - 03/01/14 03:54 PM Re: Disk Permissions [Re: HappyDog]
ganbustein Offline


Registered: 08/04/09
Originally Posted By: HappyDog
After repairing disk permissions three times in immediate succession, there is still a long list of repaired items when it's finished, most beginning with "ACL found but not expected," with many of these in iTunes.

Any ideas on what's happening? I was expecting an empty box when all were repaired.

I have heard it said the Disk Permissions is useless. Yes? No?



Yes! Repairing disk permissions is useless. It's a holdover from the days when people would install OS X just to dip their toes into, but would run back to the comforting familiarity of MacOS 9.x (or earlier) to do "real" work. MacOS had absolutely no concept of UNIX permissions, would ignore any permissions that OS X had set on a file, and would erase permissions from any file it created. DURP (Disk Utility: Repair Permissions) was never anything more than a clumsy attempt to repair at least some of the damage that MacOS would do to an OS X installation.

It has not gotten significantly less clumsy over the years. What little reason it had for existing in the first place is ancient history.

One clumsiness it has always exhibited is that it thinks the "correct" permissions are those listed in the compressed archive from which an installer package extracts the files. A compressed archive cannot specify an ACL; there's no provision for that in the file format. Instead, the package includes post-installation scripts (also extracted from the compressed archive) that run after the archive is expanded, and can do anything a shell script can do. In particular, a post-installation script can apply ACLs to the newly installed files (or even to files/folders that had previously been installed from other packages).

Those ACLs belong there, but since they weren't mentioned in the compressed archive itself, DURP thinks they're erroneous. It complains about them, but doesn't know how to remove them, so it leaves them in place where they can be complained about on the next run.


You can save yourself a fair amount of wasted computer time, and a great deal of mental aggravation, if you just stop running DURP. It is a complete and utter waste of time. The "errors" it reports are not errors. The "fixes" it claims to apply are unnecessary, often incorrect, and rarely actually applied.

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#28267 - 03/01/14 04:28 PM Re: Disk Permissions [Re: ganbustein]
artie505 Online


Registered: 08/04/09
I occasionally edit /private/etc/hosts (to add the URLs of Websites I want to block) by drag and drop (with authentication).

That results in the file's permissions being changed from

system      Read & Write
wheel        Read only
everyone   Read only

to

artie          Read & Write
everyone   Read only

How important, if at all, is it for me to repair permissions to correct that?

Thanks.

Edit: I've never noticed any ill effects from the changed perms.


Edited by artie505 (03/01/14 05:05 PM)
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The new Great Equalizer is the SEND button.

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#28273 - 03/02/14 04:38 AM Re: Disk Permissions [Re: artie505]
cyn Online

Administrator

Registered: 08/03/09
Artie, please start a new thread instead of hijacking someone else's with your question.
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#28274 - 03/02/14 07:31 AM Re: Disk Permissions [Re: ganbustein]
grelber Offline


Registered: 08/05/09
Loc: North of 49th ||
ganbustein:

Thanks for clearing up what seems to be a perpetual concern re disk permission "repairs".

Perhaps Apple's article titled "Mac OS X: Disk Utility's Repair Disk Permissions messages that you can safely ignored" (Article TS1448 and probably many others) should be replaced by the explanation in your response. It certainly would put the proper point on the issue and save innumerable queries (as it would have mine many moons ago).

Reminder: OnyX for Mac is a good maintenance tool alternative.


Edited by grelber (03/02/14 12:38 PM)
Edit Reason: OnyX reference

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#28282 - 03/03/14 12:08 AM Re: Disk Permissions [Re: cyn]
artie505 Online


Registered: 08/04/09
I think my post belongs in this thread, because it is a direct response to both HappyDog's question

Quote:
I have heard it said the Disk Permissions is useless. Yes? No?

and ganbustein's response

Quote:
You can save yourself a fair amount of wasted computer time, and a great deal of mental aggravation, if you just stop running DURP. It is a complete and utter waste of time. The "errors" it reports are not errors. The "fixes" it claims to apply are unnecessary, often incorrect, and rarely actually applied.

On the one hand, my question is rhetorical, because I've spent so much time running uneventfully with the wrong permissions that I'm no more than mildly curious about its answer, but on the other hand, it makes the point that stuff can and does happen, and suggests that an occasional running of DURP may not be a total waste of time.
_________________________
The new Great Equalizer is the SEND button.

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#28289 - 03/03/14 10:26 AM Re: Disk Permissions [Re: ganbustein]
Ira L Offline


Registered: 08/13/09
Loc: California
Originally Posted By: ganbustein
You can save yourself a fair amount of wasted computer time, and a great deal of mental aggravation, if you just stop running DURP. It is a complete and utter waste of time. The "errors" it reports are not errors. The "fixes" it claims to apply are unnecessary, often incorrect, and rarely actually applied.


That's a pretty strong and definite statement. Does that mean that all those testimonials of other problems that have been corrected by repairing permissions are just flukey coincidences?

I myself may have experienced some of those coincidences. smirk
_________________________
On a Mac since 1984.
Currently: 27" iMacs, Macbook Air, macOS 10.14.x,; iPhones, iPods and iPads galore!

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#28301 - 03/03/14 11:34 PM Re: Disk Permissions [Re: Ira L]
ganbustein Offline


Registered: 08/04/09
Originally Posted By: Ira L
That's a pretty strong and definite statement. Does that mean that all those testimonials of other problems that have been corrected by repairing permissions are just flukey coincidences?

The placebo effect is well documented and widely observed. Doing pretty much anything that you think will cause an improvement, will. At least apparently.

DURP is often accompanied by a restart, or maybe even a simple logout/login. Unlike DURP, simply restarting your computer actually can clear up some very baffling symptoms. But if you do both, any improvement will be attributed to DURP, because that feels like you're actually doing something. The restart, which should get the credit, feels like a do-nothing step.

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#28304 - 03/03/14 11:54 PM Re: Disk Permissions [Re: ganbustein]
artie505 Online


Registered: 08/04/09
On-the-mark observation about restarting!

On any number of several occasions I've found myself stymied in troubleshooting efforts because steps I've taken could be implemented only by restarting or logging out/in, either of which would have compromised my results...an infuriating catch-22.


Edited by artie505 (03/04/14 12:12 AM)
Edit Reason: Reality check
_________________________
The new Great Equalizer is the SEND button.

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#28309 - 03/04/14 09:41 AM Re: Disk Permissions [Re: ganbustein]
Ira L Offline


Registered: 08/13/09
Loc: California
Originally Posted By: ganbustein
Originally Posted By: Ira L
That's a pretty strong and definite statement. Does that mean that all those testimonials of other problems that have been corrected by repairing permissions are just flukey coincidences?

The placebo effect is well documented and widely observed. Doing pretty much anything that you think will cause an improvement, will. At least apparently.

DURP is often accompanied by a restart, or maybe even a simple logout/login. Unlike DURP, simply restarting your computer actually can clear up some very baffling symptoms. But if you do both, any improvement will be attributed to DURP, because that feels like you're actually doing something. The restart, which should get the credit, feels like a do-nothing step.


I will grant you the benefits of a restart, but repairing permissions in and of itself does not come with or require a restart. Yes, some suggestions may be to repair permissions, followed by a restart, but again, by itself DURP does not do a restart. So again, has repairing permissions made a difference?

As one who has worked with the placebo effect, I know and understand them. For me, what you say about the placebo would be more convincing if the computer itself held the belief. We are not there—yet!
_________________________
On a Mac since 1984.
Currently: 27" iMacs, Macbook Air, macOS 10.14.x,; iPhones, iPods and iPads galore!

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#28416 - 03/15/14 03:03 PM Re: Disk Permissions [Re: Ira L]
HappyDog Offline


Registered: 08/20/09
Thanks all for the responses. I'd forgotten to 'watch' this topic so got no email notifications, thus my tardiness here.

Not running Disk Permissions will save me some time when I do my SuperDuper backups.

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