SOCKET(3)                  POSIX Programmer's Manual                 SOCKET(3)



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


NNAAMMEE
       socket -- create an endpoint for communication

SSYYNNOOPPSSIISS
       #include <sys/socket.h>

       int socket(int _d_o_m_a_i_n, int _t_y_p_e, int _p_r_o_t_o_c_o_l);

DDEESSCCRRIIPPTTIIOONN
       The _s_o_c_k_e_t() function shall create an unbound socket in a
       communications domain, and return a file descriptor that can be used in
       later function calls that operate on sockets.

       The _s_o_c_k_e_t() function takes the following arguments:

       _d_o_m_a_i_n      Specifies the communications domain in which a socket is to
                   be created.

       _t_y_p_e        Specifies the type of socket to be created.

       _p_r_o_t_o_c_o_l    Specifies a particular protocol to be used with the socket.
                   Specifying a _p_r_o_t_o_c_o_l of 0 causes _s_o_c_k_e_t() to use an
                   unspecified default protocol appropriate for the requested
                   socket type.

       The _d_o_m_a_i_n argument specifies the address family used in the
       communications domain. The address families supported by the system are
       implementation-defined.

       Symbolic constants that can be used for the domain argument are defined
       in the _<_s_y_s_/_s_o_c_k_e_t_._h_> header.

       The _t_y_p_e argument specifies the socket type, which determines the
       semantics of communication over the socket. The following socket types
       are defined; implementations may specify additional socket types:

       SOCK_STREAM Provides sequenced, reliable, bidirectional, connection-
                   mode byte streams, and may provide a transmission mechanism
                   for out-of-band data.

       SOCK_DGRAM  Provides datagrams, which are connectionless-mode,
                   unreliable messages of fixed maximum length.

       SOCK_SEQPACKET
                   Provides sequenced, reliable, bidirectional, connection-
                   mode transmission paths for records. A record can be sent
                   using one or more output operations and received using one
                   or more input operations, but a single operation never
                   transfers part of more than one record. Record boundaries
                   are visible to the receiver via the MSG_EOR flag.

       If the _p_r_o_t_o_c_o_l argument is non-zero, it shall specify a protocol that
       is supported by the address family. If the _p_r_o_t_o_c_o_l argument is zero,
       the default protocol for this address family and type shall be used.
       The protocols supported by the system are implementation-defined.

       The process may need to have appropriate privileges to use the _s_o_c_k_e_t()
       function or to create some sockets.

RREETTUURRNN VVAALLUUEE
       Upon successful completion, _s_o_c_k_e_t() shall return a non-negative
       integer, the socket file descriptor.  Otherwise, a value of -1 shall be
       returned and _e_r_r_n_o set to indicate the error.

EERRRROORRSS
       The _s_o_c_k_e_t() function shall fail if:

       EEAAFFNNOOSSUUPPPPOORRTT
              The implementation does not support the specified address
              family.

       EEMMFFIILLEE All file descriptors available to the process are currently
              open.

       EENNFFIILLEE No more file descriptors are available for the system.

       EEPPRROOTTOONNOOSSUUPPPPOORRTT
              The protocol is not supported by the address family, or the
              protocol is not supported by the implementation.

       EEPPRROOTTOOTTYYPPEE
              The socket type is not supported by the protocol.

       The _s_o_c_k_e_t() function may fail if:

       EEAACCCCEESS The process does not have appropriate privileges.

       EENNOOBBUUFFSS
              Insufficient resources were available in the system to perform
              the operation.

       EENNOOMMEEMM Insufficient memory was available to fulfill the request.

       _T_h_e _f_o_l_l_o_w_i_n_g _s_e_c_t_i_o_n_s _a_r_e _i_n_f_o_r_m_a_t_i_v_e_.

EEXXAAMMPPLLEESS
       None.

AAPPPPLLIICCAATTIIOONN UUSSAAGGEE
       The documentation for specific address families specifies which
       protocols each address family supports. The documentation for specific
       protocols specifies which socket types each protocol supports.

       The application can determine whether an address family is supported by
       trying to create a socket with _d_o_m_a_i_n set to the protocol in question.

RRAATTIIOONNAALLEE
       None.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _a_c_c_e_p_t(), _b_i_n_d(), _c_o_n_n_e_c_t(), _g_e_t_s_o_c_k_n_a_m_e(), _g_e_t_s_o_c_k_o_p_t(), _l_i_s_t_e_n(),
       _r_e_c_v(), _r_e_c_v_f_r_o_m(), _r_e_c_v_m_s_g(), _s_e_n_d(), _s_e_n_d_m_s_g(), _s_e_t_s_o_c_k_o_p_t(),
       _s_h_u_t_d_o_w_n(), _s_o_c_k_e_t_p_a_i_r()

       The Base Definitions volume of POSIX.1-2008, <<nneettiinneett__iinn..hh>>,
       <<ssyyss__ssoocckkeett..hh>>

CCOOPPYYRRIIGGHHTT
       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                            SOCKET(3)
