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

GETSOCKOPT(3P)            POSIX Programmer's Manual           GETSOCKOPT(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(int socket, int level, int option_name,
           void *restrict option_value, socklen_t *restrict option_len);

DESCRIPTION         top

       The getsockopt() function manipulates options associated with a
       socket.

       The getsockopt() function shall retrieve the value for the option
       specified by the option_name argument for the socket specified by the
       socket argument. If the size of the option value is greater than
       option_len, the value stored in the object pointed to by the
       option_value argument shall be silently truncated. Otherwise, the
       object pointed to by the option_len argument shall be modified to
       indicate the actual length of the value.

       The level argument specifies the protocol level at which the option
       resides. To retrieve options at the socket level, specify the level
       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), set level 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 the getsockopt() function.

       The option_name argument specifies a single option to be retrieved.
       It can be one of the socket-level options defined in sys_socket.h(0p)
       and described in Section 2.10.16, Use of Options.

RETURN VALUE         top

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

ERRORS         top

       The getsockopt() function shall fail if:

       EBADF  The socket argument is not a valid file descriptor.

       EINVAL The specified option is invalid at the specified socket level.

       ENOPROTOOPT
              The option is not supported by the protocol.

       ENOTSOCK
              The socket argument does not refer to a socket.

       The getsockopt() function may fail if:

       EACCES The calling process does not have appropriate privileges.

       EINVAL The 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.

SEE ALSO         top

       Section 2.10.16, Use of Options, bind(3p), close(3p),
       endprotoent(3p), setsockopt(3p), socket(3p)

       The Base Definitions volume of POSIX.1‐2008, sys_socket.h(0p),
       netinet_in.h(0p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) 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 at http://www.unix.org/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, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                 2013                      GETSOCKOPT(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)