Mac OS X Example Screenshot
These warnings come from a metadata source that the OS is evaluating. On Windows, Microsoft uses a NTFS feature called Alternate Data Streams. In Windows when you open the file you get a warning...You can click OK and the ADS will remain, or you can uncheck the box "Always ask before opening this file". Unchecking that box and clicking Open/Run will delete the ADS which tells Windows that this file was downloaded from a network location. For more details on the ADS associated with a file, and/or to delete the ADS check out the Sysinternals Streams tool.
In Mac OS X, Apple uses a feature called extended Attributes. You can see that a file has extended attributes via the List Long output (ls -l) and looking for the at (@) symbol.
I downloaded synergy 1.4.8 from http://synergy-foss.org/ as an example
user:~$ ls -l synergy-1.4.8-MacOSX107-x86_64.dmg
-rw-r--r--@ 1 user group 13783645 Apr 25 17:42 synergy-1.4.8-MacOSX107-x86_64.dmg
Now let's see what Extended Attributes are associated with this file.
user:~$ xattr synergy-1.4.8-MacOSX107-x86_64.dmg
com.apple.metadata:kMDItemWhereFroms
com.apple.quarantine
Note: When opening the Disk Image we do not get a warning, however, some of the attributes follow any file copied from the Disk Image. Also, new attributes are added after opening thanks to some checks performed on Mac OS X. Just Notes, I haven't looked into these other items.
I extracted the Synergy.App so that I can use it to example the filewarning
user:~$ xattr Synergy.app/
com.apple.quarantine
If you do not want to receive this warning we need to remove (delete) the Extended Attribute com.apple.quarantine
user:~$ xattr -d com.apple.quarantine Synergy.app/
user:~$ xattr Synergy.app/
#Note: No Output since the one attribute was removed.
user:~$
When I am working with a large amount of data downloaded for tech-support purposes, and I trust the source, I will tend to remove this attribute manually from the Terminal just so that I don't have any trouble with any files not opening.
user:~$ xattr -rd com.apple.quarantine folder/
I hope this helps others dealing with there Mac and improves our knowledge. Thanks to this Macworld Article as the stepping stone to my understanding of Extended Attributes.
http://www.macworld.com/article/1145324/filewarnings.html
2 comments:
Thanks a ton. Your instructions really helped me bypass gatekeepers block on a program. It turns out that some programs can't even be opened when you right-click on them and chose "open". Tells you something about it being "damaged" and it needs to be moved to "trash". Anyways, I also want to note that having "spaces" in your programs name can be problematic but after removing those, it works like a charm. I really like your instruction how to check the associations of a program with the command: >xattr /
That really helped. Thanks a lot.
Glad I could help BlauerPlums...I try to log everything I figure out in a new OS so that at least I can refer to it later and so that others can learn as well.
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