BIND(3P) POSIX Programmer's Manual BIND(3P)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.
NAMEbind — 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 appro‐
priate 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 [EAD‐
DRINUSE].
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. Subse‐
quent 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> char‐
acter and ends with one or more trailing <slash> characters. If
the pathname names 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 direc‐
tory.
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 resolu‐
tion 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 ALSOconnect(), getsockname(), listen(), socket()
The Base Definitions volume of POSIX.1‐2008, <sys_socket.h>
COPYRIGHT
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 Electri‐
cal 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.ker‐
nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 BIND(3P)
