Mac Read & Write Permissions (w/ plists)

Question

So I'm trying to change the plist com.apple.backupd-auto.plist to adjust the timemachine schedule, and when I try to change the number (of seconds, for the schedule), I get the response that I don't have permission. So I just changed the permissions for everybody to "read and write" but then when I go to save, i get the response "cannot save ....plist."

Any ideas?

Thanks -- Kyle

Mac OSX SL 10.6.6 MacBook Pro 6,2

EDIT: using the default mac plist editor

Answer 1

Instead of dealing with permissions, I'd go on terminal and

sudo nano /System/Library/LaunchDaemons/com.apple.backupd-auto.plist

Type your password, do your edits and Control-X + y

Answer 2

Many programs replace files instead of just changing their contents. Property List Editor is one of them.

You need to temporarily give yourself permissions for the parent folder (/System/Library/LaunchDaemons/) to be able to remove and add files (which is what the program does) and you're good.

Afterwards, change the permissions of the new file to those of the original:

• owned with r/w by system
• read-only group wheel

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Alternatively, edit the file in a text editor such as TextEdit or one of the "programmers'" text editors such as TextMate. It's easily readable XML, and they don't usually replace the file.