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connect(2)
NAME
  connect - Connects two sockets

SYNOPSIS
  #include <sys/socket.h>

  int connect (
	  int socket,
	  const struct sockaddr *address,
	  size_t address_len );

  [Digital]  The following definition of the connect() function	 does not
  conform to current standards and is supported only for backward
  compatibility (see standards(5)):

  int connect (
	  int socket,
	  struct sockaddr *address,
	  int address_len );

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  connect(): XPG4-UNIX

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.


PARAMETERS
  socket
      Specifies the unique name of the socket.

  address
      Points to a sockaddr structure, the format of which is determined by
      the domain and by the behavior requested for the socket.	The sockaddr
      structure is an overlay for a sockaddr_in or sockaddr_un structure,
      depending on which of the supported address families is active.

      [Digital] If the compile-time option _SOCKADDR_LEN is defined before
      the sys/socket.h header file is included, the sockaddr structure takes
      4.4BSD behavior, with a field for specifying the length of the socket
      address.	Otherwise, the default 4.3BSD sockaddr structure is used,
      with the length of the socket address assumed to be 14 bytes or less.

      If _SOCKADDR_LEN is defined, the 4.3BSD sockaddr structure is defined
      with the name osockaddr.

  address_len
      Specifies the length of the sockaddr structure pointed to by the
      address parameter.




DESCRIPTION
  The connect() function requests a connection between two sockets.  The
  kernel sets up the communications links between the sockets; both sockets
  must use the same address format and protocol.

  The connect() function performs a different action for each of the
  following types of initiating sockets:

    ·  If the initiating socket is SOCK_DGRAM, the connect() function
       establishes the peer address.  The peer address identifies the socket
       where all datagrams are sent on subsequent send() functions. It also
       identifies the socket from where datagrams can be received; datagrams
       from other peer addresses are not delivered.

       No connections are made by thisconnect function.

    ·  If the initiating socket is SOCK_STREAM, then the connect() function
       attempts to make a connection to the socket specified by the address
       parameter.  Each communication space interprets the address parameter
       differently.

RETURN VALUES
  Upon successful completion, the connect() function returns a value of 0
  (zero).  Otherwise, a value of -1 is returned and errno is set to indicate
  the error.

ERRORS
  If the connect() function fails, errno may be set to one of the following
  values:

  [EACCESS] Search permission is denied for a component of the path prefix;
	    or write access to the named socket is denied.

  [EADDRINUSE]
	    The specified address is already in use.

  [EADDRNOTAVAIL]
	    The specified address is not available from the local machine.

  [EAFNOSUPPORT]
	    The addresses in the specified address family cannot be used with
	    this socket.

  [EALREADY]
	    A connection request is already in progress for the specified
	    socket.

  [EBADF]   The socket parameter is not valid.

  [ECONNREFUSED]
	    The attempt to connect was rejected.

  [EFAULT]  The address parameter is not in a readable part of the user
	    address space.

  [EINPROGRESS]
	    O_NONBLOCK is set for the file descriptor for the socket and the
	    connection cannot be immediately established; the connection will
	    be established asynchronously.

  [EINTR]   The connect() function was interrupted by a signal while waiting
	    for the connection to be established.  The connection
	    establishment may continue asynchronously.

  [EIO]	    An I/O error occurred while reading from or writing to the file
	    system.

  [EISCONN] The socket is already connected.

  [ELOOP]   Too many symbolic links were encountered in translating the
	    pathname in address.

  [ENAMETOOLONG]
	    A component of the pathname exceeded NAME_MAX characters, or an
	    entire pathname exceeded PATH_MAX characters.

  [ENETUNREACH]
	    No route to the network or host is present.

  [ENOENT]  A component of the pathname does not name an existing file or the
	    pathname is an empty string.

  [ENOTDIR] A component of the path prefix of the pathname in address  is not
	    a directory.

  [ENOTSOCK]
	    The socket parameter refers to a file, not a socket.

  [EPROTOTYPE]
	    The specified address has a different type than the socket bound
	    to the specified peer address.

  [ETIMEDOUT]
	    The establishment of a connection timed out before a connection
	    was made.

  [EWOULDBLOCK]
	    The socket is marked nonblocking, so the connection cannot be
	    immediately completed.  The application program can select the
	    socket for writing during the connection process.

RELATED INFORMATION
  Functions: accept(2), bind(2), socket(2), getsockname(2), select(2),
  send(2)

  Standards: standards(5)