What is the Apple_PubSub_Socket_Render environment variable for?

After running:

env  ; #from with in terminal

I see the following output:

...
Apple_PubSub_Socket_Render=/tmp/launch-pc2V6P/Render
...

What is this environment variable used for? Not really finding anything about what its for and why it is set by default.

Solution 1:

PubSub is the backend for how Safari and Mail handle RSS feeds. There are command line utilities too. From the pubsub man page:

pubsub -- Utility for managing RSS/Atom subscriptions via the PubSub framework

This variable is just part of that process.

The ability to read RSS feeds in Safari is going away in Mountain Lion, but I don't know if the entire RSS infrastructure is going away too.