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34 .\" $Id: getsockopt.2,v 1.1 1999/05/24 14:57:04 freitag Exp $
36 .\" Modified Sat Jul 24 16:19:32 1993 by Rik Faith (faith@cs.unc.edu)
37 .\" Modified Mon Apr 22 02:29:06 1996 by Martin Schulze (joey@infodrom.north.de)
38 .\" Modified Tue Aug 27 10:52:51 1996 by Andries Brouwer (aeb@cwi.nl)
39 .\" Modified Thu Jan 23 13:29:34 1997 by Andries Brouwer (aeb@cwi.nl)
40 .\" Modified Sun Mar 28 21:26:46 1999 by Andries Brouwer (aeb@cwi.nl)
41 .\" Modified 1999 by Andi Kleen <ak@muc.de>.
42 .\" Removed most stuff because it is in socket.7 now.
44 .TH GETSOCKOPT 2 2014-04-28 "Linux" "Linux Programmer's Manual"
46 getsockopt, setsockopt \- get and set options on sockets
49 .BR "#include <sys/types.h>" " /* See NOTES */"
51 .B #include <sys/socket.h>
53 .BI "int getsockopt(int " sockfd ", int " level ", int " optname ,
54 .BI " void *" optval ", socklen_t *" optlen );
55 .BI "int setsockopt(int " sockfd ", int " level ", int " optname ,
56 .BI " const void *" optval ", socklen_t " optlen );
62 manipulate options for the socket referred to by the file descriptor
64 Options may exist at multiple
65 protocol levels; they are always present at the uppermost
68 When manipulating socket options, the level at which the
69 option resides and the name of the option must be specified.
70 To manipulate options at the sockets API level,
74 To manipulate options at any
75 other level the protocol number of the appropriate protocol
76 controlling the option is supplied.
78 to indicate that an option is to be interpreted by the
82 should be set to the protocol number of
91 are used to access option values for
95 they identify a buffer in which the value for the
96 requested option(s) are to be returned.
100 is a value-result argument, initially containing the
101 size of the buffer pointed to by
103 and modified on return to indicate the actual size of
105 If no option value is to be supplied or returned,
110 and any specified options are passed uninterpreted to the appropriate
111 protocol module for interpretation.
114 contains definitions for socket level options, described below.
116 other protocol levels vary in format and name; consult the appropriate
117 entries in section 4 of the manual.
119 Most socket-level options utilize an
125 the argument should be nonzero to enable a boolean option, or zero if the
126 option is to be disabled.
128 For a description of the available socket options see
130 and the appropriate protocol man pages.
132 On success, zero is returned.
133 On error, \-1 is returned, and
135 is set appropriately.
141 is not a valid descriptor.
144 The address pointed to by
146 is not in a valid part of the process address space.
149 this error may also be returned if
151 is not in a valid part of the process address space.
157 In some cases this error can also occur for an invalid value in
165 The option is unknown at the level indicated.
170 is a file, not a socket.
172 SVr4, 4.4BSD (these system calls first appeared in 4.2BSD),
174 .\" SVr4 documents additional ENOMEM and ENOSR error codes, but does
176 .\" .BR SO_SNDLOWAT ", " SO_RCVLOWAT ", " SO_SNDTIMEO ", " SO_RCVTIMEO
179 POSIX.1-2001 does not require the inclusion of
181 and this header file is not required on Linux.
182 However, some historical (BSD) implementations required this header
183 file, and portable applications are probably wise to include it.
193 (and this is what 4.x BSD and libc4 and libc5 have).
194 Some POSIX confusion resulted in the present
200 Several of the socket options should be handled at lower levels of the
214 This page is part of release 3.68 of the Linux
217 A description of the project,
218 information about reporting bugs,
219 and the latest version of this page,
221 \%http://www.kernel.org/doc/man\-pages/.