Command to Apply Extended Attributes?

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Level 6

10,587 points

Command to Apply Extended Attributes?

Is there a command that allow me to apply certain extended attributes to a file? I'm trying to reproduce a situation so that I can report a problem. I'd like to be able to modify the attributes of a file so that it appears this way:

$ ls -l@ some_file.pdf

-rwxrwxrwx@ 1 billb billb 129147 Nov 5 22:14 some_file.pdf

com.apple.metadata:kMDItemDownloadedDate 53

com.apple.metadata:kMDItemWhereFroms 176

com.apple.quarantine 74

Thanks for any suggestions.

MacBook 5,2 2.0 GHz, 4GB RAM, Mac OS X (10.7)

Posted on Nov 12, 2011 1:49 PM

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Answer 1

Kappy

Level 10

362,093 points

Nov 12, 2011 1:55 PM in response to William-Boyd-Jr

The Unix command is "chflags" and/or "chmod." You might find it easier to do with a third-party utility such as BatChmod 1.6.3 or A Better Finder Attributes 5.07.

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Answer 2

William-Boyd-Jr Author

Level 6

10,587 points

Nov 12, 2011 2:09 PM in response to Kappy

Thanks for the information. I'm familiar with chmod for basic mode modification, but haven't done much with extended attributes or flags. Do you have any tips regarding modifying those "com.apple.metadata" values? The "man" pages for chmod and chflags don't mention those. Some files on my system also have metadata named things like "com.apple.Preview.UIstate.v1". I found the "mdls" command, but it's not obvious to me that mdls concerns itself with "com." items.

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Answer 3

red_menace

Level 6

17,072 points

Nov 12, 2011 2:12 PM in response to William-Boyd-Jr

Also take a look at xattr (the built-in man page has a little bit more info).

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Answer 4

Kappy

Level 10

362,093 points

Nov 12, 2011 2:18 PM in response to William-Boyd-Jr

No, I'm not a Unix pro. There's also the xattr command that may apply. I simply rely upon the man pages if I need to use Unix commands. In general, though, it's never a good idea to modify the permissions of OS X system files, but then you already know that. 🙂

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Answer 5

Kappy

Level 10

362,093 points

Nov 12, 2011 2:19 PM in response to red_menace

Sorry about my comment about xattr. I didn't see your post until after I made mine. My sincere apologies.

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Answer 6

William-Boyd-Jr Author

Level 6

10,587 points

Nov 12, 2011 2:24 PM in response to red_menace

red_menace wrote:

Also take a look at xattr (the built-in man page has a little bit more info).

That looks like the right track. Using "xattr" I just learned something: The numeric value after a metadata value in a display of "ls -l@" is the number of bytes in the value of the attribute.

I'll have to set this aside for now until tomorrow.

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Answer 7

William-Boyd-Jr Author

Level 6

10,587 points

Nov 12, 2011 2:29 PM in response to Kappy

Kappy wrote:

it's never a good idea to modify the permissions of OS X system files, but then you already know that. 🙂

Right. The files I want to modify are my own. I'm trying to recreate at will a situation where I can download a PDF file from the Web or print to PDF, then, the first time I try to open the file, Preview opens briefly, then quits. The problem is that, once I try to open a particular file, the attributes are modified, so that the next time it opens normally. If I can add the right attributes to a file so that it demonstrates the problem, I can then submit the file to Apple so that maybe they can fix the problem.

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