CONNECT(2) System Calls CONNECT(2)
connect - initiate a connection on a socket
int connect (int s, struct sockaddr *name, int namelen);
The parameter s is a socket. If it is of type SOCK_DGRAM, 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, this call attempts to make a connection to another socket.
The other socket is specified by name, which is an address in the com-
munications space of the socket. Each communications space interprets
the name parameter in its own way. Generally, stream sockets may suc-
cessfully 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 null
If the connection or binding succeeds, 0 is returned. Otherwise a -1
is returned, and a more specific error code is stored in errno.
The connect call fails if:
EBADF S is not a valid descriptor.
S is a descriptor for a file, not a socket.
The specified address is not available on this machine.
Addresses in the specified address family cannot be used
with this socket.
The socket is already connected.
Connection establishment timed out without establishing a
The attempt to connect was forcefully rejected.
The network isn't reachable from this host.
The address is already in use.
EFAULT The name parameter specifies an area outside the process
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 writing.
The socket is non-blocking and a previous connection
attempt has not yet been completed.
The following errors are specific to connecting names in the UNIX
domain. These errors may not apply in future versions of the UNIX IPC
A component of the path prefix is not a directory.
EINVAL The pathname contains a character with the high-order bit
A component of a pathname exceeded 255 characters, or an
entire path name exceeded 1023 characters.
ENOENT The named socket does not exist.
EACCES Search permission is denied for a component of the path
EACCES Write access to the named socket is denied.
ELOOP Too many symbolic links were encountered in translating
accept(2), select(2), socket(2), getsockname(2)
The connect function call appeared in 4.2BSD.
GNO 16 January 1997 CONNECT(2)
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