UNIX(7P)UNIX(7P)NAMEUNIX - local communication domain protocol
The local communication domain protocol, commonly referred to in the
industry as the Unix domain protocol, utilizes the path name address
format and the address family. This protocol can be used as an alter‐
native to the Internet protocol family (TCP/IP or UDP/IP) for communi‐
cation between processes executing on the same node. It has a signifi‐
cant throughput advantage when compared with local IP loopback, due
primarily to its much lower code execution overhead. Data is looped
back at the protocol layer (OSI Level 4), rather than at the driver
layer (OSI Level 2).
Only is supported in the address family.
The HP-UX implementation of the local communication domain protocol
does not support the flag in (see recv(2)) and (see send(2)).
socket addresses are path names. They are limited to 92 bytes in
length, including a terminating null byte. Calls to to an socket uti‐
lize an addressing structure called (see bind(2)). Pointers to this
structure should be used in all socket system calls wherever they
require a pointer to a
The include file defines this addressing structure. Within this struc‐
ture are two notable fields. The first is sun_family, which must be
set to The next is sun_path, which is the null-terminated character
string that specifies the path name of the file associated with the
socket (for example,
Only the passive (listening) socket must bind to an address. The
active socket connects to that address, but it does not need an address
of its own.
For additional information on using sockets for interprocess communica‐
tion, refer to the BSD Sockets Interface Programmer's Guide.
Socket Buffer Size
For stream and datagram sockets, the maximum send and receive buffer
size is 262142 bytes. The default buffer size is 32768 bytes. The
send and receive buffer sizes can be altered by using the and options
of the system call. Refer to getsockopt(2) for details.
was developed by the University of California, Berkeley.
SEE ALSOgetsockopt(2), socket(2).