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getsockopt(3p) — Linux manual page

PROLOG \|NAME \|SYNOPSIS \|DESCRIPTION \|RETURN VALUE \|ERRORS \|EXAMPLES \|APPLICATION USAGE \|RATIONALE \|FUTURE DIRECTIONS \|SEE ALSO \|COPYRIGHT

GETSOCKOPT(3P)          POSIX Programmer's ManualGETSOCKOPT(3P)

PROLOG top

       This manual page is part of the POSIX Programmer's Manual.  The       Linux implementation of this interface may differ (consult the       corresponding Linux manual page for details of Linux behavior), or       the interface may not be implemented on Linux.

NAME top

       getsockopt — get the socket options

SYNOPSIS top

       #include <sys/socket.h>       int getsockopt(intsocket, intlevel, intoption_name,           void *restrictoption_value, socklen_t *restrictoption_len);

DESCRIPTION top

       Thegetsockopt() function manipulates options associated with a       socket.       Thegetsockopt() function shall retrieve the value for the option       specified by theoption_name argument for the socket specified by       thesocket argument. If the size of the option value is greater       thanoption_len, the value stored in the object pointed to by theoption_value argument shall be silently truncated. Otherwise, the       object pointed to by theoption_len argument shall be modified to       indicate the actual length of the value.       Thelevel argument specifies the protocol level at which the       option resides. To retrieve options at the socket level, specify       thelevel argument as SOL_SOCKET. To retrieve options at other       levels, supply the appropriate level identifier for the protocol       controlling the option.  For example, to indicate that an option       is interpreted by the TCP (Transmission Control Protocol), setlevel to IPPROTO_TCP as defined in the<netinet/in.h> header.       The socket in use may require the process to have appropriate       privileges to use thegetsockopt() function.       Theoption_name argument specifies a single option to be       retrieved. It can be one of the socket-level options defined insys_socket.h(0p) and described inSection 2.10.16,Use of Options.

RETURN VALUE top

       Upon successful completion,getsockopt() shall return 0;       otherwise, -1 shall be returned anderrno set to indicate the       error.

ERRORS top

       Thegetsockopt() function shall fail if:EBADFThesocket argument is not a valid file descriptor.EINVALThe specified option is invalid at the specified socket              level.ENOPROTOOPT              The option is not supported by the protocol.ENOTSOCK              Thesocket argument does not refer to a socket.       Thegetsockopt() function may fail if:EACCESThe calling process does not have appropriate privileges.EINVALThe socket has been shut down.ENOBUFS              Insufficient resources are available in the system to              complete the function.The following sections are informative.

EXAMPLES top

       None.

APPLICATION USAGE top

       None.

RATIONALE top

       None.

FUTURE DIRECTIONS top

       None.

COPYRIGHT top

       Portions of this text are reprinted and reproduced in electronic       form from IEEE Std 1003.1-2017, Standard for Information       Technology -- Portable Operating System Interface (POSIX), The       Open Group Base Specifications Issue 7, 2018 Edition, Copyright       (C) 2018 by the Institute of Electrical and Electronics Engineers,       Inc and The Open Group.  In the event of any discrepancy between       this version and the original IEEE and The Open Group Standard,       the original IEEE and The Open Group Standard is the referee       document. The original Standard can be obtained online athttp://www.opengroup.org/unix/online.html .       Any typographical or formatting errors that appear in this page       are most likely to have been introduced during the conversion of       the source files to man page format. To report such errors, seehttps://www.kernel.org/doc/man-pages/reporting_bugs.html .IEEE/The Open Group                2017GETSOCKOPT(3P)

Pages that refer to this page:netinet_in.h(0p), netinet_tcp.h(0p), sys_socket.h(0p), if_freenameindex(3p), if_indextoname(3p), if_nameindex(3p), if_nametoindex(3p), send(3p), sendmsg(3p), sendto(3p), setsockopt(3p), shutdown(3p), socket(3p)