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After noticing an interesting environment variable Apple_PubSub_Socket_Render. I notice that it was referring directly to this "Render" file.

After doing a listing of "Render":

ls -lh Render

I see the following output:

srwx------ 1 user wheel 0B Mar 5 10:51 Render

As referenced in the ls manual page it notes this file as a "Socket Link"

What is a socket link?

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Interesting, that's not the sticky bit? – Matt H Mar 6 '12 at 18:04
@MattH The sticky bit indicator would be at the end. This "s" occurs where e.g. "d" would for a directory. – Kevin Reid Mar 6 '12 at 18:37
up vote 4 down vote accepted

To my understanding, it is a file that can be used to communicate between processes.

Two processes would both open the file and then read and write to it. The data they write to it is received by the reading of the other process.

It is somewhat like a network socket you would use to send data to another PC, just without all the networking.

If you want more technical details see Unix domain socket

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