This design using UNIX Domain Socket, the IPC (UNIX
Domain Socket inter-process communication) is very efficient.
In programming, it realizes Socket and network on UNIX
Domain Socket programming, the most obvious difference is
different address format, with the structure body, said
sockaddr_un Socket address is the network programming IP
address add Socket, and UNIX Domain Socket address is a
Socket type of files in the file system of path, this Socket files
created by bind () calls, if calls when the file already exists,
then bind () error returned.