connect - initiate a connection on a socket
int connect (int s, const struct sockaddr *name, int namelen);
The parameter s is a socket. If it is of type SOCK_DGRAM, then this call
specifies the peer with which the socket is to be associated; this
address is that to which datagrams are to be sent, and the only address
from which datagrams are to be received. If the socket is of type
SOCK_STREAM, then this call attempts to make a connection to another
socket. The other socket is specified by name, which is an address in
the communications space of the socket. Each communications space
interprets the name parameter in its own way. Generally, stream sockets
may successfully connect only once; datagram sockets may use connect
multiple times to change their association. Datagram sockets may
dissolve the association by connecting to an invalid address, such as a
If the connection or binding succeeds, then 0 is returned. Otherwise a
-1 is returned, and a more specific error code is stored in errno.
The call fails if:
[EBADF] S is not a valid descriptor.
[ENOTSOCK] S is a descriptor for a file, not a socket.
[EADDRNOTAVAIL] The specified address is not available on this
[EAFNOSUPPORT] Addresses in the specified address family cannot be
used with this socket.
[EISCONN] The socket is already connected.
[ETIMEDOUT] Connection establishment timed out without
establishing a connection.
[ECONNREFUSED] The attempt to connect was forcefully rejected.
[ENETUNREACH] The network isn't reachable from this host.
[EADDRINUSE] The address is already in use.
[EFAULT] The name parameter specifies an area outside the
process address space.
[EINPROGRESS] The socket is non-blocking and the connection cannot
be completed immediately. It is possible to
select(2) for completion by selecting the socket for
[EALREADY] The socket is non-blocking and a previous connection
attempt has not yet been completed.
See also the protocol-specific manual pages for other error values.
accept(2), select(2), socket(2), tcp(7P), udp(7P), unix(7F)
ABI-compliant versions of the above call can be obtained from
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