When it comes to Mac OS X troubleshooting and upkeep , remediate permissionsmay be the most frequently recommend form of action . It ’s also easily the most malign .
The truth about mend permissions lies somewhere in between . We ’re here to help you find it by assume a close flavor at doctor permission — what the function is , what it does , when you should do it , and when you should n’t .
What are permissions?
Every file and brochure on a Mac OS X intemperate drive has a placed ofpermissions — preferences that fix which user(s ) have access to each item , and exactly what that access is . For model , permissions prescribe whether or not a picky user can open and edit a particular single file . But permissions also determine which items the operating scheme — or specific parts of it — can access and modify , and which files are accessible by applications . ( Brian Tanaka offers more details about various types of permissions in this excerpt from hisTake Control of Permissions in Mac OS Xebook . )
What does repairing permissions do?
The Repair Disk Permissions function — the appendage that really performs the project of furbish up permissions — examines certain file and brochure on your Mac ’s hard parkway to see if their current permissions configurations are what Mac OS X wait them to be ; if discrepancies are regain , the offending permissions are alter to match the expected configurations .
( In Mac OS X 10.3 and later , repairing permissions also performs one other , unrelated , task : If the invisible / tmpsymbolic link — which is linked to the / private / tmpdirectory — is overlook , the link will be recreated . )
Why is it necessary to repair permissions?
If permissions on particular file are “ incorrect”—i.e . , not what Mac OS X ask them to be or not what they call for to be for your Mac ’s normal surgical procedure — you may live problem when the operating system judge to access or change those Indian file . For example , you may have trouble access to your report , printing , launch applications , or even part up your Mac . Similarly , if an app — from Apple or a third - company developer — need memory access to a particular file or brochure to function , and the permit on that item have alter in a way that prevents such access , the app may not function properly ( or at all ) . The Repair Disk Permissions function can prepare such problem by see that certain files have the correct permissions .
There ’s also a security constituent here : Many system - level files have permission set a peculiar way of life so that applications or users that should n’t be tamper with those files ca n’t . If the permit on sure system of rules - layer files somehow get changed so that access to those files is no longer restrict , you ’ve got the potential for a major security issue . Repairing permissions can resolve such issues by resetting permit on those single file to preclude unauthorized access .
How do I repair permissions?
The Repair Disk Permissions function is part of Apple ’s Disk Utility ( in /Applications / Utilities ) . After launch Disk Utility , select the desired disc — generally your startup disk — in the list to the left , then click the First Aid tab . At the bottom of the First Aid panel , get through the Repair Disk Permissions button . ( You could instead use the Verify Disk Permissions option to preview any potential repairs before perform them , but for most user there ’s picayune welfare from this supernumerary stair . )
Permissions can also be remedy via the shell ( Terminal ) by using the control
How does the Repair Disk Permissions function know what the “correct” permissions are?
When you habituate Apple ’s Installer utility to put in software program ( such as Mac OS X itself or an OS X update ) , the installation package ( the.pkgfile you double - click to start installation , or that Software Update downloads in the setting for an robotic installation ) generally leaves behind areceipt — a pocket-sized Mac OS X packet that includes information about every file cabinet installed , including the license each filing cabinet should have . This receipt is placed in /Library / Receipts . When you execute the Repair Disk Permissions map , it examine the gross in the /Library / Receipts directoryof the disk being repaired — which means the feature works only on volume with Mac OS X put in — and compares the data in the receipt with the actual files on your drive . If the Repair Disk Permissions function find a file cabinet with permissions that differ from what a receipt claim they should be , that file ’s permissions are reset to their reception - specify time value . ( If you ’re curious about the information contained in a reception , the easiest way to see it is to use the utilityPacifist [ ; August 2006 ] ; simply drag and drop the appropriate receipt into the dovish windowpane and you ’ll be present with a list of all files installed by the similarly - distinguish installing package , along with each file ’s original permissions . )
It ’s worth noting here that although the role is hollo “ RepairDisk Permissions , ” what is actually happen is that file ’ permissions are beingresetorrestoredto a particular state . It ’s possible — though not vulgar — for a particular file cabinet ’s permissions to differ from what a receipt claims they should be without those permissions actually being “ break . ”
Areallfiles affected by Repair Disk Permissions?
No . As you may have inferred from the above description , only those files put in using OS X ’s Installer utilityandwhose installation parcel leave behind a proper reception in /Library / Receipts are affected by the Repair Disk Permissions function . This mean that most of the files dissemble by the Repair Disk Permissions function are organisation - story files , program Indian file , or system add - ons — not applications installed by pull - and - pearl , and not your documents or other drug user - degree files . ( See thenext sectionfor entropy about third - party computer software . )
But beyond that , onlycertainreceipts are referenced , all of them consort with OS - 10 - refer software . This limit of the Repair Disk Permissions function has been turn over around the World Wide Web , but you’re able to substantiate it yourself with a turn of Terminal savvy : By using the
These receipts are all from installations related to Mac OS X or Apple ’s Xcode / Developer Tools . Given that files not listed in the above receipts wo n’t be affected by the Repair Disk Permissions function , this means that renovate permission is mainly a tool for fixing license - related problem withOS - level Apple software system .
Whydoes the Repair Disk Permissions function look at only these receipts?
These receipt are explicitly listed within the codification ofDiskManagementTool , the component of OS X that actually perform the job of renovate license . you may swear this by using the stick with bidding in Terminal :
( I ’ve placed the command in a scrolling boxful so it would n’t be broken falsely . The output from that command is a leaning of all receipts included in the computer code of DiskManagementTool . )
Does repairing permissions affect third-party application files?
Apple’sdescriptionof the Repair Disk Permissions function seems to imply thatanysoftware , include third - party software package , installed using Installer and accompanied by a receipt in /Library / Receipts is affected by repairing permission . However , we know from the previous answer that this is n’t the example . The only third - company software package affected by indemnify permissions is software package include with Mac OS X and set up by the Mac OS X Installer ; for example , the Flash internet browser hack - in ( /Library / Internet Plug - Ins / flashplayer.xpt ) and — in older versions of Mac OS X — Microsoft ’s Internet Explorer web internet browser .
It ’s gentle to verify that third - party software is n’t affected . For exemplar , I changed the permissions on the fileNuFile.plugin , a third - company contextual carte plugin , from their original values . Since NuFile.plugin was installed using OS X ’s Installer public-service corporation and a receipt , NuFileInstaller1 - 8.pkg , is present in /Library / Receipts , you might wait that the Repair Disk Permissions function would reestablish NuFile.plugin ’s permissions to their original values . It does n’t . I performed a interchangeable test on the TiVoDesktop System Preferences pane with similar results .
Although some might argue that restricting the Repair Disk Permissions go to Apple - establish computer software is a limit , it ’s also good security . If third - political party receipts were used as references when repairing permissions , a patch of malware could leave behind a reception design to maliciously alter permissions on system - stage files — for example , to impute more - accessible permissions on commonly secure files and directories . This could be a major security risk .
That said , keep in mind that many third - political party software intersection rely on components of Mac OS X. So although repairing permissions may notdirectlyaffect third - political party software system , if a permission - related bug with OS X ’s own files is causing a problem with third - company software , the Repair Disk Permissions map could affect that software by bushel the underlying campaign of the problem .
Can I get rid of receipts in the /Library/Receipts folder?
If you remove receipts from /Library / Receipts , the Repair Disk Permissions mapping will no longer affect files reference in those reception ; if a permit release with one of those file is causing a job , you wo n’t be able to fasten the trouble by compensate permissions . But beyond that , some receipts are necessary for the Repair Disk Permissions run to mould at all , as depict below . In gain , receipts are often used byMac OS X ’s Software Updateand third - party software installers to ascertain whether or not you ’ve already got a particular piece of software package installed .
On today ’s larger hard drives , even a jam - packed Receipts folder is likely to be a few hundred MB or less in sizing ; it ’s best to simply pass on the contents of this leaflet alone .
Can I move the files affected by the Repair Disk Permissions function?
file cabinet locations are hard - bait in receipts ; if you move files heel in a reception , those files wo n’t be check when you repair permissions . This is a good ground not to move Apple - establish software package .
I’ve read that before repairing permissions, you need to boot from the volume being repaired because Repair Disk Permissions uses the /Library/Receipts folder on the boot volume to determine correct permissions. Is this true?
This was true in early versions of Mac OS X. In fact , it used to be that if a permissions payoff prevented you from booting off your normal inauguration volume , you necessitate to revivify permission while booted from the Mac OS X Install disc . Then , once you were able to successfully reboot from your normal volume , you used the procedure again to ensure the “ right ” receipt were used . However , in all recent interpretation of OS X , Disk Utility use the /Library / Receipts leaflet on the mass actually being vivify , iron heel or not .
Whenever I try to repair permissions, I get an error that states…
permit me infer : First Aid conk out : Disk Utility arrest vivify permissions on ’ [ volume name ] ’ because the following error was encountered : No valid packagesorError : No valid packages ( -9997).As explained above , the Repair Disk Permissions function uses receipts located in /Library / Receipts to square off what the correct system - level file license should be . At a lower limit , the subroutine requires that a receipt namedBaseSystem.pkg — which outlines the default permissions for core Mac - OS - pertain files and folders — be present . If this reception is miss , the subprogram will go bad with one or both of the above errors .
If you find yourself in this position and theBaseSystem.pkgpackage is no longer present anywhere on your hard drive — so you ca n’t simply move it back to the Receipts folder — Applerecommendscopying it from another computer running the same variant of Mac OS X as your own . If that ’s not an option , either , then Apple recommends reinstall Mac OS X. ( If your Mac OS X Install disc is for the same interlingual rendition of Mac OS X as is lead on your Mac — for object lesson , 10.4.2 — you may do a standard install , which simply put back existing organisation files with newer translation . However , if your Install disc would install an older variant of Mac OS X — for example , 10.4.0 when your Mac is currently run 10.4.6 — you need to perform an Archive and Install installation and then update to the latest variant of OS X via Software Update . )
Why do I see so many “special permissions” errors when I repair permissions?
The forgetful answer is “ Because you have n’t yet updated to Mac OS go 10.4.6 or later . ” The long answer is that Apple has at times settle , for various cause , that sure newly - instal or latterly - update Indian file should actually havedifferentpermissions than those of an earlier version . For example , say a file installed with Mac OS X 10.4.0 had particular permit , adumbrate in theBaseSystem.pkgreceipt , but Apple shift the permissions for that filing cabinet in a later update to Mac OS X. In such a scenario , there would be a discrepancy between the desired permissions on the file and what the Old receipt exact those license should be ; the Repair Disk Permissions function would attempt to “ desexualise ” the permission on that single file to match the original BaseSystem.pkg receipt , even though those permission are now “ incorrect . ”
To avoid such erroneous repairs , recent Apple updates include a file calledHintFile.plist , instal in /System / Library / PrivateFrameworks / DiskManagement.framework / Versions / A / Resources , that lists any file permissions that should dissent from what ’s number in receipts . Essentially , this single file tell the Repair Disk Permissions subroutine , “ disregard what those receipts say about file - such - and - such ; the permission on that file shouldreallybe … ”
In older interlingual rendition of Mac OS X , you would see this conversation stretch on your screen in the form of “ special permission ” errors in Disk Utility . However , as part of theMac OS X 10.4.6 Update , Apple modified the Repair Disk Permissions function so that it no longer deliver these messages in the Disk Utility window . Nothing has switch in terms of what ’s happening behind the view ; you just no longer have to read the narrative . If you ’ve got an honest-to-goodness version ( pre-10.4.6 ) of Mac OS X install , you could simply snub any substance that include the phrase “ We are using special permissions . ”
What causes permissions to change?
If you range the Web , you ’ll see many claims that “ permissions do n’t change on their own . ” And to a large extent , that ’s true — for permission to change , something , or someone , must interchange them . But there are a telephone number of way permissions can be change . Here are a few illustration :
This is n’t an thorough list , but it does show that although permissions do n’t as if by magic shift , there are enough ways for them tobechanged that you should look at a permissions issue as a potential cause if you go through problems with your Mac . ( Apple provide a interchangeable tilt of possible causes of permissions issue inthis Knowledge Base article . )
Is repairing permissions “useless,” as I’ve read on the Web?
repair permissions is not go to situate all of your Mac ’s problems , or even most of them . Many of the problems for which I see the function commend as a possible solution — for instance , slow Internet performance , problems with drug user - level app preferences , or even permissions issues that foreclose you from deleting document — are unconvincing to be solved by repairing license . However , the procedurewillfix those problem interrelate to incorrect system - related permissions . How common such problem are is a national of fairly acute public debate , but what is n’t debatable is that such problems do in fact pass , and the Repair Disk Permissions function is quick enough and easy enough to practice that repairing permission is one of the first procedures Apple ’s technical school supporting representatives will enquire you to do ( and most Geniuses in Apple Stores will do ) to your Mac when you ’re get a job .
A similar but not quite as uttermost argument I get word is that you should n’t utilise the Repair Disk Permissions function as a troubleshooting tool unless you’resureyou have a permissions - touch trouble . This go like logical advice , and advice that wee sense for any troubleshooting procedure — in an ideal humanity , you ’d use only the appropriate troubleshooting tool for the line . But the trouble with this debate is that most Mac OS cristal users do n’t get laid how to determine if a problem is truly because of a permissions consequence . And even among experient trouble shooter , many function are used as much to eliminate potential causes of problem as they are to actively define problems . animate permissions is useful in this context of use because it ’s a quick and easy way to eliminate a organisation - degree permissions publication as the causa of a problem .
If repairing permissions is useful in general, why doesn’t Apple recommend it as routine maintenance?
Apple does , quite explicitly :
That ’s take from Mac Help — in both Panther and Tiger — right on your Mac ; an on-line version can be readhere . exchangeable statement can be ground in other Support articles . Now , to be fairish , I suspect that Apple do such good word not because it ’s usually necessary , but rather because , as mentioned in the previous item , if a permissions - related problem does occur , compensate permissions is a quick and gentle way to fix it . The fact that Apple specifically recommends the subprogram after installing package seems to confirm my suspicions that big installers are the most unwashed cause of permissions glitch .
ShouldI repair permissions as routine maintenance?
Some citizenry exact that , just like periodically running a record repair utility , repairing permissions regularly will help your Mac run more smoothly . But there ’s a fundamental difference here : nonaged drive or directory equipment casualty — the variety that can be catch early and easily fixed — can impact the means files and folder are written to and turn up on your hard thrust . That imply regular check of your thrust can forestall more serious problems , include data departure , down the road .
However , that ’s seldom the case with incorrect license . Even if a permissions issue does cause job , it should n’t head to more serious consequence ; things specifically affected by these “ bad ” license may not make for properly , but one incorrect permission does n’t lead to other wrong permissions , and a license issue will seldom lead to information loss . In other words , the benefits of being “ proactive ” about permissions repairs are underage for most user ; you ’ll be served just as well by repairing permissionsafteryou experience a problem . ( This is peculiarly true in Mac OS X 10.3 and afterwards , as license - pertain problems occur much less frequently now than with earlier versions of Mac OS X. )
That said , if it makes you feel safer to do the chore regularly , it ’s highly unlikely to suffer anything ( seebelow ) . And if you ’re in a higher - risk group — for case , someone who installslotsof software — amend license as “ maintenance ” or after a software update , as Apple recommends , may avoid a bit of inconvenience by secure wrong permissions before they attest in detectable symptom .
Do I need to repair permissionsbeforeinstalling an update to Mac OS X?
In a word , no . When you install a Mac OS cristal update , you ’re required to authenticate — provide an admin - degree username and password — in order for the installation to go forward . When you authenticate , you ’re let the installer to run with the equivalent ofrootaccess . What this mean is that the installer is not constrained by Mac OS X ’s permission system — it disregard the normal limitation of file and leaflet permissions . This is necessary for Installer to be able to update Mac OS X , but , more important for the current give-and-take , it also means that “ incorrect ” permissions should n’t make problem with the installation .
The only actual benefit to repairing permissionsbeforea Mac OS decade update is that if you do so , then instantly set up the update , and then repair permission again straight off afterwards , you may be pretty confident that any permission issues that are incur are a result of the update . But at that peak you ’ve also mend the problem(s ) , so the pre - install “ repair ” provide you with little more than academic knowledge .
Do I need to repair permissionsafterinstalling an update to Mac OS X?
If you experience Modern problems now after induction , repairing permit is the first step you should take , but there ’s no real demand to do so as a matter of habit . As explained above , Mac OS X ’s Installer installs files with the necessary permissions and then leave a reception or gross that outline those permission . Unless a problem occurs with the installation , the license outlined in the receipt(s ) will match the permissions on the actual files that have been put in ; in other words , no repairs will be necessary .
However , that ’s not to say that permissions problems ca n’t happen during an installation . I ’ve consider plenty of ascertain , honest reports of Macs that have been “ permissions perfect ” before an installation but have experience permissions - related problems afterwards . Even Applenotes that“Permission problems sometimes find after you refresh your system or put in newfangled software . ” ( I personally had a problem with a particular update to Panther [ Mac OS X 10.3 ] where none of my non - boot drive would hop on . It turned out that during the update instalment , the license on the unseeable /Volumes directory had been changed . A quick Repair Disk Permissions , and I was proficient to go . ) But these are the exception , not the rule — the vast majority of users will be fine restore permission only after they feel a job .
But as I mentioned with regard to quotidian maintenance , if it help you sleep better at dark to recompense permissions after each OS decade update , do n’t let me break you . And it ’s likely more efficacious to do so after software updates or initiation than on a regular ( e.g. , hebdomadal ) schedule .
Given that Apple recommends repairing permissions after updating Mac OS X, why doesn’t Apple’s Installer do it automatically?
I asked Apple that very question ; the company turn down to comment . For what it ’s deserving , repairing permissions is n’t the only procedure to fall into this category ; there are many other useful procedures and processes Mac OS X does n’t mechanically perform . For example , it ’s a skilful idea to periodically check your hard drive for problems , and Apple recommends doing so ; although Mac OS X could easily perform this task on a weekly basis , it does n’t .
Can repairing permissionshurtanything?
Critics of frequent permission fixing lay claim that the procedure can in reality do more harm than good by resetting permission that have been changed from their defaults — presumably for good understanding — by the user , an program , or an installer . Although this is a valid logical argument in theory , in realism it ’s not something most user should vex about . For starters , remember that the Repair Disk Permissions function does n’t impact user - level data file , so your data is safe . The procedure also does n’t have-to doe with third - company software . So you ’re left with only OS X ’s own system of rules - level files , and ifApplemakes such changes , it already has two mechanisms — receipt files and theHintFile.plistfile — for ensuring that the Repair Disk Permissions function sets permit properly . ( There have been rare examples of Mac OS X update work fine until the substance abuser revivify permissions ; however , these issues were due to errors in Apple ’s installer scripts and receipts — not the Repair Disk Permissions single-valued function — that were fixed in revised versions of the updates . )
What about more advance users who intentionally alter permission on organisation - floor files — clearly an unsupported procedure — in lodge to modify the scheme in some way ? It ’s fairish to expect that people savvy enough to perform such tweaks should also be savvy enough to ( a ) read the possible import ; ( b ) keep track of such change and remember to re - implement them after repairing permissions ; and ( c ) forefend repairing permission unless absolutely necessary . Similarly , if a piece of software change permission in a way that could be reset by repairing permissions , the developer of the software should account for that fact — either in software or by clear noting the issue in the package ’s documentation . This is especially true of software package installers likely to be used by multitude who are n’t inevitably experts — it ’s the developer ’s responsibility to prevent a common function recommended by Apple from breaking the software . The fact that these modern users and software products exist is scarcely a convincing argument against your typical Mac user repairing permissions , even frequently .
And recollect to keep this risk in view : A very small minority of users pull off scheme - stratum Apple component that also happen to be affect by the Repair Disk Permissions mapping . I know of few mass who tweak their Macs more , and install more package , than I do , and I ’ve never fallen dupe to such a scenario . In fact , the last fourth dimension even I heard of such a situation in the real man was back in Jaguar ( Mac OS X 10.2 ) when a finical procedure for customizing OS X ’s built - in mail host was involve by repairing permissions .
Bottom line : It ’s highly unlikely that repairing permission will adversely sham your Mac or its software package ; the chances of the Repair Disk Permissions function doing harm are much , much lower than the chances of it helping if you ’re experiencing a job . For the immense majority of Mac user , it ’s a harmless operation , and the small telephone number of citizenry who might be adversely affected should already be cognisant of such risk of infection . If you ’re come to , utilize Repair Disk Permissions ’ Verify manner — which shows which permit would be reset but does n’t actually make any changes — first ; if everything looks effective , then use fixture mode .
What if a permissions problem is preventing my Mac from starting up?
It ’s rarefied that a permission - related issue will in reality forbid your Mac from start up up ; however , it does happen . If you discover yourself in a position where you ca n’t bulge up your Mac , one of the easiest troubleshooting procedures call for start up from the Install disk ( cadmium or DVD ) that follow with your Mac and then using Disk Utility — via the Utilities menu that appears when booted from the disc — to check your strong drive for impairment . But you may also use the Repair Disk Permissions role while bring up from the disc to guarantee that system - point Indian file permit are correct . ( mark that Apple has anumberofarticlesdealing with other case of startup problem ; there ’s a good chance your trouble have nothing to do with permissions . )
A similar root can be found in the freeAppleJack (; August 2006 ) , a third - company maintenance and troubleshooting utility . Like Disk Utility , AppleJack can renovate permission on your inauguration cause , but because it runs in individual - user mode at startup , it can often set permit - related issue that are foreclose Mac OS X from starting up properly , and it does n’t require you to have your O cristal Install record on helping hand . Unfortunately , AppleJack is n’t yet compatible with Intel - based Macs .
( Given that you may access a shell at startup viasingle - user mode , and that I antecedently showed you the command for repairing permissions via Terminal , you might believe that you could restore permission in individual - user mode using that command . Unfortunately , for various reasons , this does n’t exploit without manually pop out a telephone number of other service first , a process too complicated to get into here . I commend using either your Install disc or AppleJack . )
What about Mac OS X Server?
For the most part , the info in this article practice equally well to Mac OS X Server . However , since a server administrator is more likely to purposely change the permissions on system - level files than a distinctive user — Apple has specifically recommended a few such change over the years — be aware that if you make such changes , using the Repair Disk Permissions routine may return them .
I’m curious about other coverage of this topic. Where can I go?
Here are connexion to a number of other clause around the Web that talk over repairing permissions :
UPDATE 8/26/06 : This story was updated on 8/27/2006 to lend information about where the tilt of revenue is located and how to fix permissions via Terminal . selective information about Mac OS X Server and a inclination of link to other article on the topic of repairing license were also added .
DAN FRAKES is aMacworldsenior editor in chief .
