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PROLOG

       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

       bind — bind a name to a socket

SYNOPSIS

       #include <sys/socket.h>

       int bind(int socket, const struct sockaddr *address,
           socklen_t address_len);

DESCRIPTION

       The  bind() function shall assign a local socket address address to a socket identified by
       descriptor socket that has no local socket address  assigned.  Sockets  created  with  the
       socket() function are initially unnamed; they are identified only by their address family.

       The bind() function takes the following arguments:

       socket      Specifies the file descriptor of the socket to be bound.

       address     Points  to  a  sockaddr  structure  containing  the address to be bound to the
                   socket. The length and format of the address depend on the address  family  of
                   the socket.

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

       The socket specified by socket may require the process to have appropriate  privileges  to
       use the bind() function.

       If  the  address  family  of  the  socket  is  AF_UNIX and the pathname in address names a
       symbolic link, bind() shall fail and set errno to [EADDRINUSE].

       If the socket address cannot be assigned immediately and O_NONBLOCK is set  for  the  file
       descriptor  for  the  socket,  bind()  shall  fail and set errno to [EINPROGRESS], but the
       assignment  request  shall  not  be  aborted,  and  the  assignment  shall  be   completed
       asynchronously.  Subsequent  calls to bind() for the same socket, before the assignment is
       completed, shall fail and set errno to [EALREADY].

       When the assignment has been performed asynchronously,  pselect(),  select(),  and  poll()
       shall indicate that the file descriptor for the socket is ready for reading and writing.

RETURN VALUE

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

ERRORS

       The bind() function shall fail if:

       EADDRINUSE
              The specified address is already in use.

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

       EAFNOSUPPORT
              The specified address is not  a  valid  address  for  the  address  family  of  the
              specified socket.

       EALREADY
              An assignment request is already in progress for the specified socket.

       EBADF  The socket argument is not a valid file descriptor.

       EINPROGRESS
              O_NONBLOCK  is set for the file descriptor for the socket and the assignment cannot
              be immediately performed; the assignment shall be performed asynchronously.

       EINVAL The socket is already bound to an  address,  and  the  protocol  does  not  support
              binding to a new address; or the socket has been shut down.

       ENOBUFS
              Insufficient resources were available to complete the call.

       ENOTSOCK
              The socket argument does not refer to a socket.

       EOPNOTSUPP
              The socket type of the specified socket does not support binding to an address.

       If the address family of the socket is AF_UNIX, then bind() shall fail if:

       EACCES A  component  of  the  path  prefix denies search permission, or the requested name
              requires writing in a directory with a mode that denies write permission.

       EDESTADDRREQ or EISDIR
              The address argument is a null pointer.

       EIO    An I/O error occurred.

       ELOOP  A loop exists in symbolic links encountered during resolution of  the  pathname  in
              address.

       ENAMETOOLONG
              The length of a component of a pathname is longer than {NAME_MAX}.

       ENOENT A component of the path prefix of the pathname in address does not name an existing
              file or the pathname is an empty string.

       ENOENT or ENOTDIR
              The pathname in address contains at least one non-<slash> character and  ends  with
              one  or  more  trailing  <slash>  characters.  If the pathname without the trailing
              <slash> characters would name an existing file, an [ENOENT] error shall not occur.

       ENOTDIR
              A component of the path prefix of the pathname in address names  an  existing  file
              that  is neither a directory nor a symbolic link to a directory, or the pathname in
              address contains at least one non-<slash> character  and  ends  with  one  or  more
              trailing  <slash> characters and the last pathname component names an existing file
              that is neither a directory nor a symbolic link to a directory.

       EROFS  The name would reside on a read-only file system.

       The bind() function may fail if:

       EACCES The specified address is protected and the current user does not have permission to
              bind to it.

       EINVAL The address_len argument is not a valid length for the address family.

       EISCONN
              The socket is already connected.

       ELOOP  More  than  {SYMLOOP_MAX}  symbolic links were encountered during resolution of the
              pathname in address.

       ENAMETOOLONG
              The length of a pathname exceeds {PATH_MAX}, or pathname resolution of  a  symbolic
              link produced an intermediate result with a length that exceeds {PATH_MAX}.

       The following sections are informative.

EXAMPLES

       The  following  code  segment  shows  how  to create a socket and bind it to a name in the
       AF_UNIX domain.

           #define MY_SOCK_PATH "/somepath"

           int sfd;
           struct sockaddr_un my_addr;

           sfd = socket(AF_UNIX, SOCK_STREAM, 0);
           if (sfd == -1)
               /* Handle error */;

           memset(&my_addr, '\0', sizeof(struct sockaddr_un));
                                /* Clear structure */
           my_addr.sun_family = AF_UNIX;
           strncpy(my_addr.sun_path, MY_SOCK_PATH, sizeof(my_addr.sun_path) -1);

           if (bind(sfd, (struct sockaddr *) &my_addr,
               sizeof(struct sockaddr_un)) == -1)
               /* Handle error */;

APPLICATION USAGE

       An application program can retrieve  the  assigned  socket  name  with  the  getsockname()
       function.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       connect(), getsockname(), listen(), socket()

       The Base Definitions volume of POSIX.1‐2017, <sys_socket.h>

COPYRIGHT

       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 at http://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, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .