4.2BSD/usr/man/man2/connect.2

.TH CONNECT 2 "7 July 1983"
.UC 4
.SH NAME
connect \- initiate a connection on a socket
.SH SYNOPSIS
.nf
.ft B
#include <sys/types.h>
#include <sys/socket.h>
.PP
.ft B
connect(s, name, namelen)
int s;
struct sockaddr *name;
int namelen;
.fi
.SH DESCRIPTION
The parameter
.I s
is a socket.
If it is of type SOCK_DGRAM,
then this call permanently specifies the peer to which
datagrams are to be sent;
if it is of type SOCK_STREAM,
then this call attempts to make a connection to
another socket.
The other socket is specified by
.I name
which is an address in the communications space of the socket.
Each communications space interprets the
.I name
parameter in its own way.
.SH "RETURN VALUE
If the connection or binding succeeds, then 0 is returned.
Otherwise a \-1 is returned, and a more specific error
code is stored in \fIerrno\fP.
.SH "ERRORS
The call fails if:
.TP 20
[EBADF]
.I S
is not a valid descriptor.
.TP 20
[ENOTSOCK]
.I S
is a descriptor for a file, not a socket.
.TP 20
[EADDRNOTAVAIL]
The specified address is not available on this machine.
.TP 20
[EAFNOSUPPORT]
Addresses in the specified address family cannot be used with this socket.
.TP 20
[EISCONN]
The socket is already connected.
.TP 20
[ETIMEDOUT]
Connection establishment timed out without establishing a connection.
.TP 20
[ECONNREFUSED]
The attempt to connect was forcefully rejected.
.TP 20
[ENETUNREACH]
The network isn't reachable from this host.
.TP 20
[EADDRINUSE]
The address is already in use.
.TP 20
[EFAULT]
The \fIname\fP parameter specifies an area outside
the process address space.
.TP 20
[EWOULDBLOCK]
The socket is non-blocking and the
and the connection cannot
be completed immediately.
It is possible to
.IR select (2)
the socket while it is connecting by selecting it for writing.
.SH SEE ALSO
accept(2), select(2), socket(2), getsockname(2)