GNU C Library (libc) Programming Guide

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16.3.2 Setting the Address of a Socket

Use the bind function to assign an address to a socket. The prototype for bind is in the header file sys/socket.h. For examples of use, see Local Socket Example, or see Inet Example.

— Function: int bind (int socket, struct sockaddr *addr, socklen_t length)

The bind function assigns an address to the socket socket. The addr and length arguments specify the address; the detailed format of the address depends on the namespace. The first part of the address is always the format designator, which specifies a namespace, and says that the address is in the format of that namespace.
The return value is 0 on success and -1 on failure. The following errno error conditions are defined for this function:

EBADF
The socket argument is not a valid file descriptor.
ENOTSOCK
The descriptor socket is not a socket.
EADDRNOTAVAIL
The specified address is not available on this machine.
EADDRINUSE
Some other socket is already using the specified address.
EINVAL
The socket socket already has an address.
EACCES
You do not have permission to access the requested address. (In the Internet domain, only the super-user is allowed to specify a port number in the range 0 through IPPORT_RESERVED minus one; see Ports.)

Additional conditions may be possible depending on the particular namespace of the socket.