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32 .\" @(#)unix.4 8.1 (Berkeley) 6/9/93
39 .Nd UNIX-domain protocol family
41 .Fd #include <sys/types.h>
42 .Fd #include <sys/un.h>
46 protocol family is a collection of protocols
47 that provides local (on-machine) interprocess
48 communication through the normal
58 filesystem pathnames for addressing.
61 addresses are variable-length filesystem pathnames of
62 at most 104 characters.
66 .Bd -literal -offset indent
78 causes a socket file to be created in the filesystem.
81 removed when the socket is closed\(em\c
83 must be used to remove the file.
87 protocol family does not support broadcast addressing or any form
90 matching on incoming messages.
91 All addresses are absolute- or relative-pathnames
95 Normal filesystem access-control mechanisms are also
96 applied when referencing pathnames; e.g., the destination
105 protocol family is comprised of simple
106 transport protocols that support the
112 sockets also support the communication of
114 file descriptors through the use of the
123 Any valid descriptor may be sent in a message.
124 The file descriptor(s) to be passed are described using a
126 that is defined in the include file
127 .Aq Pa sys/socket.h .
128 The type of the message is
130 and the data portion of the messages is an array of integers
131 representing the file descriptors to be passed.
132 The number of descriptors being passed is defined
133 by the length field of the message;
134 the length field is the sum of the size of the header
135 plus the size of the array of file descriptors.
137 The received descriptor is a
139 of the sender's descriptor, as if it were created with a call to
141 Per-process descriptor flags, set with
145 passed to a receiver.
146 Descriptors that are awaiting delivery, or that are
147 purposely not received, are automatically closed by the system
148 when the destination socket is closed.
153 .%T "An Introductory 4.3 BSD Interprocess Communication Tutorial"
158 .%T "An Advanced 4.3 BSD Interprocess Communication Tutorial"