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.\" @(#)bind.2 8.1 (Berkeley) 6/4/93
.\" $FreeBSD$
.\"
.Dd August 18, 2016
.Dt BIND 2
.Os
.Sh NAME
.Nm bind
.Nd assign a local protocol address to a socket
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/socket.h
.Ft int
.Fn bind "int s" "const struct sockaddr *addr" "socklen_t addrlen"
.Sh DESCRIPTION
The
.Fn bind
system call
assigns the local protocol address to a socket.
When a socket is created
with
.Xr socket 2
it exists in an address family space but has no protocol address assigned.
The
.Fn bind
system call requests that
.Fa addr
be assigned to the socket.
.Sh NOTES
Binding an address in the UNIX domain creates a socket in the file
system that must be deleted by the caller when it is no longer
needed (using
.Xr unlink 2 ) .
.Pp
The rules used in address binding vary between communication domains.
Consult the manual entries in section 4 for detailed information.
.Pp
For maximum portability, you should always zero the socket address structure
before populating it and passing it to
.Fn bind .
.Sh RETURN VALUES
.Rv -std bind
.Sh ERRORS
The
.Fn bind
system call will fail if:
.Bl -tag -width Er
.It Bq Er EAGAIN
Kernel resources to complete the request are
temporarily unavailable.
.It Bq Er EBADF
The
.Fa s
argument
is not a valid descriptor.
.It Bq Er 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.
.It Bq Er EINVAL
The
.Fa addrlen
argument is not a valid length for the address family.
.It Bq Er ENOTSOCK
The
.Fa s
argument
is not a socket.
.It Bq Er EADDRNOTAVAIL
The specified address is not available from the local machine.
.It Bq Er EADDRINUSE
The specified address is already in use.
.It Bq Er EAFNOSUPPORT
Addresses in the specified address family cannot be used with this socket.
.It Bq Er EACCES
The requested address is protected, and the current user
has inadequate permission to access it.
.It Bq Er EFAULT
The
.Fa addr
argument is not in a valid part of the user
address space.
.El
.Pp
The following errors are specific to binding addresses in the UNIX domain.
.Bl -tag -width EADDRNOTAVA
.It Bq Er ENOTDIR
A component of the path prefix is not a directory.
.It Bq Er ENAMETOOLONG
A component of a pathname exceeded 255 characters,
or an entire path name exceeded 1023 characters.
.It Bq Er ENOENT
A prefix component of the path name does not exist.
.It Bq Er ELOOP
Too many symbolic links were encountered in translating the pathname.
.It Bq Er EIO
An I/O error occurred while making the directory entry or allocating the inode.
.It Bq Er EROFS
The name would reside on a read-only file system.
.It Bq Er EISDIR
An empty pathname was specified.
.El
.Sh SEE ALSO
.Xr connect 2 ,
.Xr getsockname 2 ,
.Xr listen 2 ,
.Xr socket 2
.Sh HISTORY
The
.Fn bind
system call appeared in
.Bx 4.2 .
