MacOS Extended Attributes – How to Verify if an Extended Attribute Exists

extended-attributesmacos

When running

 xattr -d com.apple.quarantine /Applications/XXX.app

sometimes I get

 xattr: /Applications/XXX.app: No such xattr: com.apple.quarantine

How does one verify if any named attribute exist for a given XXX.app?

Best Answer

The following xttar command causes both the attribute names and corresponding values to be displayed, if any exist.

xattr -l file

You can also use the ls command:

ls -@ file

That said, the ... No such xattr: com.apple.quarantine message is a non-fatal message, meaning there no real need to make it conditional, and if your goal is to remove the com.apple.quarantine extended attribute from a lot of files at once in a given directory, then cd to the target directory and use the following command:

for f in *; do xattr -dr com.apple.quarantine "$f" 2>/dev/null; done

The above one-liner will delete the com.apple.quarantine extended attribute off every file that has it and act as if the entire contents of the directory recursively were also specified (so that every file in the directory tree is acted upon), thats the -r option, while not showing errors for files that don't have the target extended attribute. (That's what the 2>/dev/null does.)

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Darwin is open source. I'm guessing you'll need to modify OS level things, a kernel extension, etc. and add this ability.

Or you could modify the dynamic-view tools you know (fs_usage and/or lsof), have them check if a file is being created, and append the process chain that created it into the Spotlight comment, etc.

MacOS – How to clean ._AppleDouble files from unix packages

I need to learn proper xattr usage.

Apparently, xattr has a "clear" (-c) command that can be applied using a wildcard (*), as follows,

xattr -cr *

This results in a recursive removal of all ._AppleDouble files from the current folder on down (the -r flag does recursive, while the -c flag clears them), thus making the process a trivial one line command.

This does not however clear out the .DS_Store files. For that, you can employ the good old "find" command:

find . -type f -name .DS_Store -delete

This will find and delete any .DS_Store files from the current directory on down (recursively).

Lastly, we can bring it all together in the form of an alias that is called upon by simply typing "xat" (put the following in your .bash_profile):

alias xat='find . -type f -name .DS_Store -delete && xattr -cr *'

Now just run "xat" on any directory and it'll strip those pesky resource forks and remove those irritating .DS_Store files from anything inside of it.

Best Answer

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