+Abstract socket namespace
+~~~~~~~~~~~~~~~~~~~~~~~~~
+UNIX domain sockets are a traditional way to communicate between
+processes on the same machine. They are always reliable (see above)
+and don't reorder datagrams. Unlike TCP and UDP, UNIX domain sockets
+support passing open file descriptors or process credentials to
+other processes.
+
+The usual way to set up a UNIX domain socket (as obtained from
+socket(2)) for listening is to first bind the socket to a file system
+pathname and then call listen(2), then accept(2). Such sockets are
+called _pathname sockets_ because bind(2) creates a special socket
+file at the specified path. Pathname sockets allow unrelated processes
+to communicate with the listening process by binding to the same path
+and calling connect(2).
+
+There are two problems with pathname sockets:
+
+ * The listing process must be able to (safely) create the
+ socket special in a directory which is also accessible to
+ the connecting process.
+
+ * After an unclean shutdown of the listening process, a stale
+ socket special may reside on the file system.
+
+The abstract socket namespace is a non-portable Linux feature which
+avoids these problems. Abstract sockets are still bound to a name,
+but the name has no connection with file system pathnames.
+