(or "local sockets" in POSIX-speak)

A type of local socket which has an associated path and inode on the filesystem. This is useful if you want sockets that can only be used with the local machine. You could get a similar result by using Internet domain sockets and connecting to, but that would be wasteful and a potential security hazard if you don't bind() properly. UNIX domain sockets are sometimes done with the X Window System, or say, esd and things like that.

Specified with domain family constant PF_UNIX (or PF_LOCAL in POSIX), or address family AF_UNIX (again, AF_LOCAL in POSIX). The address struct, struct sockaddr_un has 2 members: sun_family (set to AF_UNIX/AF_LOCAL) and sun_path (a char array; the filesystem path of the socket)