Using Skype 7.37 on OS X El Capitan, observing this highly unusual behaviour:

  1. I receive a photo in a Skype chat.
  2. I click "Reveal in Finder", Skype places the photo in my Downloads folder as it is configured to do.
  3. I move the file to eg. Dropbox.
  4. I click "Reveal in Finder" again - Skype correctly opens the Dropbox folder!
  5. I move the file again to eg. Desktop and rename it by appending "test" or such.
  6. I click "Reveal in Finder" again - Skype correctly opens Desktop!!!

In steps 4 and 6 I was totally expecting Skype to download the photo again and store it into Downloads.

Can anyone else replicate this behaviour? How is Skype able to do this?

  • 1
    That's why it's called "Finder" & not "Explorer"... it's doing its job. Skype isn't doing it. Move it to another partition & it will lose it, though, as the 'original' has now gone..
    – Tetsujin
    Commented Oct 11, 2016 at 9:22
  • Can you elaborate? What exactly is Skype asking the Finder to open?
    – vektor
    Commented Oct 11, 2016 at 9:24
  • a file reference, which Finder is tracking. No OS lets individual apps handle files, that's the OS's job. The app hands off to the OS, the OS does its thing... which on Mac includes knowing where it went. That's why Windows has 'Explorer'... because it's $%^&* useless at following files round & makes you go look for them yourself every time ;)
    – Tetsujin
    Commented Oct 11, 2016 at 9:26
  • If you write this up as an answer and provide references to some developer documentation regarding these file references, I will accept it. At the moment, it's still a bit too vague to me - for example, in a POSIX system I still have no idea how this would be done. From my experience, it's usually the full path to the file that is being sent around between applications, which obviously is not the case here.
    – vektor
    Commented Oct 11, 2016 at 9:30
  • The reason I'm not posting as an answer is I don't know how it does it, only that it does & always has.
    – Tetsujin
    Commented Oct 11, 2016 at 9:33

1 Answer 1


I don't use Skype but I suspect the fact it came from Skype is stored in one of two places. To find out, copy a Skype download to your Home directory and start Terminal. If your file is called, say, photo.jpg, you would run:

mdls photo.jpg

to list the metadata and something in there will refer to Skype or its bundle identifier.

Alternatively, run:

xattr -l photo.jpg

and see if Skype is listed in its WhereFrom attribute.


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