1sys_un.h(0P) POSIX Programmer's Manual sys_un.h(0P)
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6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
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12 sys/un.h — definitions for UNIX domain sockets
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15 #include <sys/un.h>
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18 The <sys/un.h> header shall define the sockaddr_un structure, which
19 shall include at least the following members:
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22 sa_family_t sun_family Address family.
23 char sun_path[] Socket pathname.
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25 The sockaddr_un structure is used to store addresses for UNIX domain
26 sockets. Pointers to this type shall be cast by applications to struct
27 sockaddr * for use with socket functions.
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29 The <sys/un.h> header shall define the sa_family_t type as described in
30 <sys/socket.h>.
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32 The following sections are informative.
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35 The size of sun_path has intentionally been left undefined. This is
36 because different implementations use different sizes. For example, 4.3
37 BSD uses a size of 108, and 4.4 BSD uses a size of 104. Since most
38 implementations originate from BSD versions, the size is typically in
39 the range 92 to 108.
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41 Applications should not assume a particular length for sun_path or
42 assume that it can hold {_POSIX_PATH_MAX} bytes (256).
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44 Although applications are required to initialize all members (including
45 any non-standard ones) of a sockaddr_in6 structure (see
46 <netinet_in.h>), the same is not required for the sockaddr_un struc‐
47 ture, since historically many applications only initialized the stan‐
48 dard members. Despite this, applications are encouraged to initialize
49 sockaddr_un structures in a manner similar to the required initializa‐
50 tion of sockaddr_in6 structures.
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53 None.
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56 None.
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59 <netinet_in.h>, <sys_socket.h>
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61 The System Interfaces volume of POSIX.1‐2017, bind(), socket(), socket‐
62 pair()
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65 Portions of this text are reprinted and reproduced in electronic form
66 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
67 table Operating System Interface (POSIX), The Open Group Base Specifi‐
68 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
69 Electrical and Electronics Engineers, Inc and The Open Group. In the
70 event of any discrepancy between this version and the original IEEE and
71 The Open Group Standard, the original IEEE and The Open Group Standard
72 is the referee document. The original Standard can be obtained online
73 at http://www.opengroup.org/unix/online.html .
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75 Any typographical or formatting errors that appear in this page are
76 most likely to have been introduced during the conversion of the source
77 files to man page format. To report such errors, see https://www.ker‐
78 nel.org/doc/man-pages/reporting_bugs.html .
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82IEEE/The Open Group 2017 sys_un.h(0P)