setsockopt(3N-xs)             (X/OPEN SOCKETS)            setsockopt(3N-xs)

NAME
     setsockopt - set the socket options

SYNOPSIS
     cc [flag ...] file ... -lxnet [library ...]

     #include <sys/socket.h>

     int setsockopt(int socket, int level, int optionname, const void
                    *optionvalue, sizet optionlen);

DESCRIPTION
     The setsockopt function sets the option specified by the optionname
     argument, at the protocol level specified by the level argument, to
     the value pointed to by the optionvalue argument for the socket asso-
     ciated with the file descriptor specified by the socket argument.

     The level argument specifies the protocol level at which the option
     resides. To set options at the socket level, specify the level argu-
     ment as SOLSOCKET. To set options at other levels, supply the
     appropriate protocol number for the protocol controlling the option.
     For example, to indicate that an option will be interpreted by the TCP
     (Transport Control Protocol), set level to the protocol number of TCP,
     as defined in the <netinet/in.h> header, or as determined by using
     getprotobyname.

     The optionname argument specifies a single option to set. The
     optionname argument and any specified options are passed uninter-
     preted to the appropriate protocol module for interpretations. The
     <sys/socket.h> header defines the socket level options. The socket
     level options can be enabled or disabled. The options are as follows:

     SODEBUG        Turns on recording of debugging information. This
                     option enables or disables debugging in the underlying
                     protocol modules. This option takes an int value.

     SOBROADCAST    Permits sending of broadcast messages, if this is sup-
                     ported by the protocol. This option takes an int
                     value.

     SOREUSEADDR    Specifies that the rules used in validating addresses
                     supplied to bind should allow reuse of local
                     addresses, if this is supported by the protocol. This
                     option takes an int value.

     SOKEEPALIVE    Keeps connections active by enabling the periodic
                     transmission of messages, if this is supported by the
                     protocol. This option takes an int value.

                     If the connected socket fails to respond to these mes-
                     sages, the connection is broken and processes writing
                     to that socket are notified with a SIGPIPE signal.



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setsockopt(3N-xs)             (X/OPEN SOCKETS)            setsockopt(3N-xs)

     SOLINGER       Lingers on a close if data is present. This option
                     controls the action taken when unsent messages queue
                     on a socket and close is performed. If SOLINGER is
                     set, the system blocks the process during close until
                     it can transmit the data or until the time expires. If
                     SOLINGER is not specified, and close is issued, the
                     system handles the call in a way that allows the pro-
                     cess to continue as quickly as possible. This option
                     takes a linger structure, as defined in the
                     <sys/socket.h> header, to specify the state of the
                     option and linger interval.

     SOOOBINLINE    Leaves received out-of-band data (data marked urgent)
                     in line. This option takes an int value.

     SOSNDBUF       Sets send buffer size. This option takes an int value.

     SORCVBUF       Sets receive buffer size. This option takes an int
                     value.

     For boolean options, 0 indicates that the option is disabled and 1
     indicates that the option is enabled.

     Options at other protocol levels vary in format and name.

RETURN VALUE
     Upon successful completion, setsockopt returns 0. Otherwise, -1 is
     returned and errno is set to indicate the error.

ERRORS
     The setsockopt function will fail if:

     EBADF           The socket argument is not a valid file descriptor.

     EINVAL          The specified option is invalid at the specified
                     socket level or the socket has been shut down.

     ENOPROTOOPT     The option is not supported by the protocol.

     ENOTSOCK        The socket argument does not refer to a socket.

     The setsockopt function may fail if:

     ENOMEM          The memory available was not sufficient to complete
                     the operation.

     ENOBUFS         The resources available in the system are not suffi-
                     cient to complete the call.

     ENOSR           There were insufficient STREAMS resources available
                     for the operation to complete.



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setsockopt(3N-xs)             (X/OPEN SOCKETS)            setsockopt(3N-xs)

APPLICATION USAGE
     The setsockopt function provides an application program with the means
     to control socket behavior. An application program can use setsockopt
     to allocate buffer space, control timeouts, or permit socket data
     broadcasts. The <sys/socket.h> header defines the socket-level options
     available to setsockopt.

     Options may exist at multiple protocol levels. The SO options are
     always present at the uppermost socket level.

SEE ALSO
     bind(3N-xs), getprotoent(3N-xs), getsockopt(3N-xs), socket(3N-xs),
     ip(7).









































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