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what does the repair disk premission exactly do?
- Thread starter SLJ
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It sets the permissions of the files on the chosen volume to "default". I don't know why, but occasionally the permissions on (many) files on the boot volume get messy.
At first I thought the repair util only restored the permissions of the files "known" to the OS X startup CD. But somehow it also will correct permissions on files for instance installed by Adobe.
Maybe installers leave fingerprints behind, and maybe installers change some systems files' permissions in order to be able to change them. Possibly the installer cannot change them back, so that's where disk util comes in.
Simple example: installer needs to change a string in a driver (kext), making it read/write for the installer, but should be read only under normal circumstances... and will be changed back to r -only after disk util, repair permissions have been executed.
Any other ideas?
At first I thought the repair util only restored the permissions of the files "known" to the OS X startup CD. But somehow it also will correct permissions on files for instance installed by Adobe.
Maybe installers leave fingerprints behind, and maybe installers change some systems files' permissions in order to be able to change them. Possibly the installer cannot change them back, so that's where disk util comes in.
Simple example: installer needs to change a string in a driver (kext), making it read/write for the installer, but should be read only under normal circumstances... and will be changed back to r -only after disk util, repair permissions have been executed.
Any other ideas?
okay, here's the best method of explanation i can give you...
Any file or folder in OS X has permissions dictating which users can read, write, or run (execute) a program/file.
Many of the system files will become so altered that you (your username) cannot read, write or execute things that you need need to... For instance, iTunes might try to read it's song lists on starting, and find them locked to your username (iTunes will run as a process owned by you, so it is governed by the same rules that you are).
Repairing permissions checks and resets the permissions on all of the system files (and i think programs made by apple). It won't do every file, just system ones, which is why you can only repair permissions on disks that have OS X installed on them...
Then, when it's finished, you and your programs will have proper clearance within the system to access specific files.
hope that helps??
pnw
Any file or folder in OS X has permissions dictating which users can read, write, or run (execute) a program/file.
Many of the system files will become so altered that you (your username) cannot read, write or execute things that you need need to... For instance, iTunes might try to read it's song lists on starting, and find them locked to your username (iTunes will run as a process owned by you, so it is governed by the same rules that you are).
Repairing permissions checks and resets the permissions on all of the system files (and i think programs made by apple). It won't do every file, just system ones, which is why you can only repair permissions on disks that have OS X installed on them...
Then, when it's finished, you and your programs will have proper clearance within the system to access specific files.
hope that helps??
pnw
I understand how permissions repair works, but I've always wondered how it stores the data for what the correct permissions ought to be. Does it keep a table of all system files on the disk? What if that table's permissions get messed up? (that one was thrown in just to be hypothetical)
Paulwhannel, that was a very clear explanation, but why would the permissions change if, for example, I'm the only person using my computer? Why should they change? Do I change them myself without knowing it, or does the system just change them automatically?