GUIDE: Zap PRAM, Repair Permissions, & run FSCK

edesignuk

Moderator emeritus
Original poster
Mar 25, 2002
19,077
1
London, England
The idea for this quick GUIDE was thought up in this thread by kingjr3. Like the networking thread the idea of this is to have a quick point of reference for those common questions.


How to Zap PRAM

Zapping PRAM is simple, just reboot your Mac and hold down "Command(the Apple key)+Option(the Alt key)+P+R" while it is booting, when you hear the startup sound for the seond time the operation is complete, and you can release the key combination. Now just let your Mac boot as normal.

How to Repair Permissions

• Navigte to "Applications > Utilities", and open up "Disk Utility".

http://upc.*************/uploads/forums/diskutilityapp.jpg

• Select the volume where your OS resides, and hit the "Repair Disk Permissions" button.

http://upc.*************/uploads/forums/diskutility.jpg

If you are comfortable with using the Terminal (Applications > Utilities > Terminal.app), you can also enter this command to run repair permissions - "sudo diskutil repairpermissions /" (without the quotes), just enter your password when prompted.

http://upc.*************/uploads/forums/terminalrepairperms.jpg

How to run FSCK

• Restart your Mac holding down "Command(the Apple key)+S" key to enter 'Single user mode'.
• Type "fsck -f", and hit return.
• Once complete type "reboot" and hit return to reboot you Mac back in to OS X as normal.


If there is anything that you think is wrong here, or you think I have missed any vital steps out, please post and let me know so that I can ammend this.
 

aus_dave

macrumors regular
Jan 6, 2004
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0
edesignuk, can you explain why you can't just double-click on the Disk Utility application in Applications/Utilities (to repair permissions)?
 

Elan0204

macrumors 65816
Apr 16, 2002
1,083
2
Chicago, IL
NusuniAdmin said:
ya i dont know why she said that...even apple does not have that

http://docs.info.apple.com/article.html?artnum=152064
edesignuk is a he. His avatar is not him. :)

People have said in the forums that permisions are repaired "better" if you aren't using the volume that you are repairing permissions on when you do the repair. That is why they recommend the CD method.

However, others have said that since new files are added and permissions might be adjusted by the x.x.x (i.e. X.3.5) updates, repairing permissions without the CD is better, since these changes are not on the original install disc.
 

NusuniAdmin

macrumors 6502a
Nov 19, 2003
870
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Elan0204 said:
edesignuk is a he. His avatar is not him. :)

People have said in the forums that permisions are repaired "better" if you aren't using the volume that you are repairing permissions on when you do the repair. That is why they recommend the CD method.

However, others have said that since new files are added and permissions might be adjusted by the x.x.x (i.e. X.3.5) updates, repairing permissions without the CD is better, since these changes are not on the original install disc.
lol ok great to know :p
 

yellow

Moderator emeritus
Oct 21, 2003
15,925
1
Portland, OR
Elan0204 said:
However, others have said that since new files are added and permissions might be adjusted by the x.x.x (i.e. X.3.5) updates, repairing permissions without the CD is better, since these changes are not on the original install disc.
This is correct. Do not boot from the CD to repair permissions. Repairing permissions compares the permissions detailed in the BOM (Bill Of Materials) of entries in /Library/Receipts/ to those of your installed applications and OS updates. Anything that is out of whack will have it's permissions fixed. The BOM files on the CD are woefully out of date in most cases.

As an alternative, you can repair permissions from the command line:

sudo diskutil repairpermissions /
 

yellow

Moderator emeritus
Oct 21, 2003
15,925
1
Portland, OR
edesignuk said:
• Type "fsck -f", and hit return.
Some might argue that you leave yourself open to a minor security risk by not specifying WHICH fsck you want to run, as in "/sbin/fsck -fy". Just typing fsck means any old fsck that appears in the SUM path first would get run instead. We're talking potential trojans here.. but this is not to say that someone couldn't replace /sbin/fsck either.
 

edesignuk

Moderator emeritus
Original poster
Mar 25, 2002
19,077
1
London, England
aus_dave said:
edesignuk, can you explain why you can't just double-click on the Disk Utility application in Applications/Utilities (to repair permissions)?
As far as I understood it you needed to be logged in as root, or boot off the CD to have the necessary permissions to make permission changes to system files. Am I wrong then? I know I am not the only one who does this, I learnt this way of doing it from posts on this forum :confused: We need to get a definite answer on this, the Apple doc link isn't working for me btw :confused:

As for the fsck thing, I believed -f was the correct switch to use with the command as it forces a full check regardless, this seems to make most sence to me.

edit: OK, the link Rower provided in this thread to apples repair permisisons guide seems clear. I've changed this guide to run disk utility from within OS X, and not from the CD :)
 

Nermal

Moderator
Staff member
Dec 7, 2002
18,677
1,183
New Zealand
edesignuk said:
I've changed this guide to run disk utility from within OS X, and not from the CD :)
Now add 'at the startup tone' or similar to the end of the instructions for zapping PRAM :)
 

edesignuk

Moderator emeritus
Original poster
Mar 25, 2002
19,077
1
London, England
Diatribe said:
Yep, you should add to the PRAM zapping that it is done while starting up. This is a newbie guide after all, isn't it? :D

Edit: beaten to it :)
I really thought I had said you do it while rebooting actually, I must be going crazy. Anyway, it's fixed now :)
 

CmdrLaForge

macrumors 601
Feb 26, 2003
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around the world
Hi edesignuk,

great idea to add another guide. The one thing I am missing, that it does just explain HOW to do the task, but does not explain WHY and WHEN.

Could you add that ? Would be great

Cheers
LaForge
 

edesignuk

Moderator emeritus
Original poster
Mar 25, 2002
19,077
1
London, England
CmdrLaForge said:
Hi edesignuk,

great idea to add another guide. The one thing I am missing, that it does just explain HOW to do the task, but does not explain WHY and WHEN.

Could you add that ? Would be great

Cheers
LaForge
Problem is there are so many reasons why you might be advised to do any of these things. It's not like it's one cause that leads you do do these things.
 

NusuniAdmin

macrumors 6502a
Nov 19, 2003
870
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*begins to write a Stickies note* edesignuk is male, not female *end note*

sorry bout that edesignuk :p

*sets note as a floating window*
 

yellow

Moderator emeritus
Oct 21, 2003
15,925
1
Portland, OR
edesignuk said:
Problem is there are so many reasons why you might be advised to do any of these things. It's not like it's one cause that leads you do do these things.
I concur. However, you could dispel the myths surrounding the repairing of permissions. IMO:

It's only necessary/advised to repair permissions after installing anything that requires an admin password. This includes, but is not limited to, system/security updates.
 

CmdrLaForge

macrumors 601
Feb 26, 2003
4,374
2,447
around the world
edesignuk said:
Problem is there are so many reasons why you might be advised to do any of these things. It's not like it's one cause that leads you do do these things.
OK, if so - then thats a problem. Even I have no idea what FSCK could be good for and I thought I know something about Macs. Obviously I don't
:( :eek:

Cheers
LaForge
 

wrldwzrd89

macrumors G5
Jun 6, 2003
12,106
73
Solon, OH
CmdrLaForge said:
OK, if so - then thats a problem. Even I have no idea what FSCK could be good for and I thought I know something about Macs. Obviously I don't
:( :eek:

Cheers
LaForge
CmdrLaForge - you familiar with Disk Utility and its "Repair" option for hard disks (the one that looks for and fixes directory problems)? That button is nothing more than a graphical front-end to the fsck utility, which actually checks and fixes your disk. Essentially, running fsck is equivalent to opening Disk Utility, selecting the disk you want checked, and clicking Repair.
 

yellow

Moderator emeritus
Oct 21, 2003
15,925
1
Portland, OR
Actually.. if we want to be entirely correct, the "repair disk" button is a frontend for:

sudo diskutil repairdisk /

Which is a Appleized version of fsck.
 

wrldwzrd89

macrumors G5
Jun 6, 2003
12,106
73
Solon, OH
yellow said:
Actually.. if we want to be entirely correct, the "repair disk" button is a frontend for:

sudo diskutil repairdisk /

Which is a Appleized version of fsck.
You're saying it's three layers deep? Disk Utility -> diskutil -> fsck instead of Disk Utility -> fsck? Didn't know that - thanks yellow.