man-pages/man2/bind.2

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.\" Modified Mon Oct 21 23:05:29 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
.\" Modified 1998 by Andi Kleen
.\" $Id: bind.2,v 1.3 1999/04/23 19:56:07 freitag Exp $
.\" Modified 2004-06-23 by Michael Kerrisk <mtk-manpages@gmx.net>
.\"
.TH BIND 2 2004-06-23 "Linux 2.6.7" "Linux Programmer's Manual"
.SH NAME
bind \- bind a name to a socket
.SH SYNOPSIS
.B #include <sys/types.h>
.br
.B #include <sys/socket.h>
.sp
.BI "int bind(int " sockfd ", const struct sockaddr *" my_addr \
", socklen_t " addrlen );
.SH DESCRIPTION
.B bind
gives the socket
.I sockfd
the local address
.IR my_addr .
.I my_addr
is
.I addrlen
bytes long.
Traditionally, this is called \(lqassigning a name to a socket.\(rq
When a socket is created with
.BR socket (2),
it exists in a name space (address family) but has no name assigned.
.PP
It is normally necessary to assign a local address using
.B bind
before a
.B SOCK_STREAM
socket may receive connections (see
.BR accept (2)).

The rules used in name binding vary between address families.  Consult
the manual entries in Section 7 for detailed information. For
.B AF_INET
see
.BR ip (7),
for
.B AF_UNIX
see
.BR unix (7),
for
.B AF_APPLETALK
see
.BR ddp (7),
for
.B AF_PACKET
see
.BR packet (7),
for
.B AF_X25
see
.BR x25 (7)
and for
.B AF_NETLINK
see
.BR netlink (7).

.SH "RETURN VALUE"
On success, zero is returned.  On error, \-1 is returned, and
.I errno
is set appropriately.
.SH ERRORS
.TP
.B EACCES
The address is protected, and the user is not the superuser.
.TP
.B EBADF
.I sockfd
is not a valid descriptor.
.TP
.B EINVAL
The socket is already bound to an address.  This may change in the future:
see
.I linux/unix/sock.c
for details.
.TP
.B ENOTSOCK
Argument is a descriptor for a file, not a socket.
.PP
The following errors are specific to UNIX domain 
.RB ( AF_UNIX ) 
sockets:
.TP
.B EACCES
Search permission is denied on a component of the path prefix.
(See also
.BR path_resolution (2).)
.TP
.B EFAULT
.I my_addr
points outside the user's accessible address space.
.TP
.B EINVAL
The
.I addrlen
is wrong, or the socket was not in the
.B AF_UNIX
family.
.TP
.B ELOOP
Too many symbolic links were encountered in resolving
.IR my_addr .
.TP
.B ENAMETOOLONG
.I my_addr
is too long.
.TP
.B ENOENT
The file does not exist.
.TP
.B ENOMEM
Insufficient kernel memory was available.
.TP
.B ENOTDIR
A component of the path prefix is not a directory.
.TP
.B EROFS
The socket inode would reside on a read-only file system.
.SH BUGS
The transparent proxy options are not described.
.SH "CONFORMING TO"
SVr4, 4.4BSD (the
.B bind
function first appeared in BSD 4.2).  SVr4 documents additional
.BR EADDRNOTAVAIL , 
.BR EADDRINUSE , 
and
.B ENOSR 
general error conditions, and
additional 
.B EIO
and
.B EISDIR
Unix-domain error conditions.
.SH NOTE
The third argument of
.B bind
is in reality an int (and this is what BSD 4.* and libc4 and libc5 have).
Some POSIX confusion resulted in the present socklen_t, also used by glibc.
See also
.BR accept (2).
.SH "SEE ALSO"
.BR accept (2),
.BR connect (2),
.BR getsockname (2),
.BR listen (2),
.BR path_resolution (2),
.BR socket (2),
.BR getaddrinfo (3),
.BR ip (7),
.BR socket (7)