I’m con­fused by file per­mis­sions

Get to grips with file per­mis­sions and man­age all of your files


In OS X (but not iOS) you can have more than one user ac­count – typ­i­cally one for your­self and per­haps oth­ers for your fam­ily.

At the heart of this sits a sys­tem known as File Sys­tem Per­mis­sions and un­der­stand­ing this can make your life a lot eas­ier. Ev­ery sin­gle item on your Mac – all the files you have cre­ated, and ev­ery file and folder in the op­er­at­ing sys­tem – has per­mis­sions at­tached to it.

These per­mis­sions de­ter­mine who ‘owns’ the file, and who else has ac­cess to it. In Unix, the sys­tem that sits be­neath OS X, there are three types of ac­cess: read­ing, writ­ing and ex­e­cut­ing. Read de­ter­mines who gets to view the con­tents of a file, Write de­ter­mines who gets to edit (and save) the file, and Ex­e­cute de­ter­mines which user ac­counts can run an app or script.

In OS X, you only get to change who owns the file, and who gets to read or write to it. You’ll need to dig into Ter­mi­nal to ad­just the ex­e­cu­tion sta­tus of files. But for the most part, you’ll be fine ad­just­ing per­mis­sions in­side OS X’s graph­i­cal in­ter­face.

Chang­ing file and folder per­mis­sions

Select any file, or folder, in OS X and choose File > Get Info ( ç-I). Scroll down to find Shar­ing & Per­mis­sions. For most files, you will see your ac­count name fol­lowed by (Me) and the priv­i­lege set to Read & Write. Be­low your ac­count will be two fur­ther users: ‘staff’ and ‘ev­ery­one’ (both typ­i­cally set to Read Only.) The former group is all the ac­counts you have set up on your Mac, and the lat­ter one in­cludes any other ac­counts that may ac­cess your Mac (such as a Guest ac­count or another Mac on your net­work).

You change the per­mis­sion sta­tus of files and fold­ers in the Get Info win­dow. If you are the owner of the file, just click in the Priv­i­lege column next to staff or ev­ery­one and change them to Read & Write, Read Only, No Ac­cess (only for ‘ev­ery­one’), or Write Only (for fold­ers).

Most of the time you’ll want to change per­mis­sions on a file that you don’t own (typ­i­cally be­cause your ac­cess to it is blocked). This block may be be­cause you have trans­ferred the file from one user ac­count space to another, or be­cause you are try­ing to view files on a dif­fer­ent user ac­count. To change the per­mis­sions for a file, or folder, owned by another user, you first click the pad­lock icon in the bot­tom-right cor­ner of the Get Info win­dow. En­ter an Ad­min user’s cre­den­tials and click OK. Now you can change the priv­i­leges.

If you have moved a file man­u­ally from one ac­count to another, you may see the name field set to ‘sys­tem’ rather than your name (or the name of another user ac­count). You can change the staff group to Read & Write and ac­cess the file that way, or make your­self the owner of the file. Click the + but­ton and choose your ac­count name from the list of Users & Groups, then click Select to add it to the item’s priv­i­leges. Click the Set­tings cog and choose ‘Make me the owner’. Choose ‘sys­tem’ in the Name list and click the – (mi­nus) but­ton to get rid of it. You’re now the owner of the file as if you’d cre­ated it. You can also use this method to make files owned by other peo­ple yours.

View­ing fold­ers in other ac­counts

A com­mon prob­lem is try­ing to view the con­tents of a folder on another ac­count on your Mac. Choose Go > Com­puter and select your startup drive and then the Users folder on it to see fold­ers for each user with an ac­count on your Mac. Open a folder for an ac­count that isn’t yours, and you’ll see a red Stop icon next to most fold­ers. Try­ing to view the con­tents of one of these fold­ers bring up the er­ror: “The folder can’t be opened be­cause you don’t have per­mis­sion to see its con­tents.”

You can by­pass this lock by ad­just­ing the per­mis­sions. Select a locked folder, choose File > Get Info, click the Lock icon and en­ter an Ad­min user’s cre­den­tials. Click the + but­ton, choose your name from the list and click Select. Change your priv­i­lege to Read & Write and you’ll be able to ac­cess that folder as if it was in your ac­count.

As long as you have ac­cess to an ad­min ac­count, you can over­ride per­mis­sions.

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