05-30-2011
After select() returns without error you pass the socked handler to accept(), accept() will return a new socket ONLY for that particular connection/session, the first socked is free again to be handled by select() and loses relation with previous client. You should not write or read anything on the main socket.
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socket(7) Miscellaneous Information Manual socket(7)
NAME
socket - interprocess communications
DESCRIPTION
Sockets are communication endpoints that allow processes to communicate either locally or remotely. They are accessed by means of a set of
system calls (see socket(2)).
The following requests are defined in (see ioctl(2)):
If the int with the address
arg is non-zero, the socket is put into non-blocking mode. Otherwise, the socket is put into blocking mode. Blocking mode
is the default. The request is equivalent to the request, although using is not recommended. See accept(2), connect(2),
recv(2), and send(2) for an explanation of how non-blocking mode is used.
For SOCK_STREAM sockets, the number of bytes currently readable from this socket is returned in the integer with the address
arg. For SOCK_DGRAM sockets, the number of bytes currently readable, plus the size of the sockaddr structure (defined in is
returned in the integer with the address arg.
For SOCK_STREAM TCP sockets, on return the integer with the address arg is non-zero if the inbound TCP stream has been read up
to where the out-of-band data byte starts. Otherwise, the inbound TCP stream has not yet been read up to where the out-of-
band data byte starts. For sockets other than SOCK_STREAM TCP sockets, on return the integer with the address arg is always
zero.
This request sets the process group or process
ID associated with the socket to be the value of the integer with the address arg. A process group or process ID associated
with the socket in this manner is signaled when the state of the socket changes: is delivered upon the receipt of out-of-
band data; is delivered if the socket is asynchronous, as described in below. If the value of the integer with the address
arg is positive, the signal is sent to the process whose process ID matches the value specified. If the value is negative,
the signal is sent to all the processes that have a process group equal to the absolute value of the value specified. If
the value is zero, no signal is sent to any process. It is necessary to issue this request with a non-zero integer value to
enable the signal delivery mechanism described above. The default for the process group or process ID value is zero.
This request returns the process group or process
ID associated with the socket in the integer with the address arg. See the explanation for above for more details on the
meaning of the integer value returned.
If the integer whose address is
arg is non-zero, this request sets the state of the socket as asynchronous. Otherwise, the socket is put into synchronous
mode (the default). Asynchronous mode enables the delivery of the signal when either of the following conditions is met.
o New data arrives.
o For connection-oriented protocols, whenever additional outgoing buffer space becomes available or the connection is
established or broken.
The process group or process ID associated with the socket must be non-zero in order for signals to be sent. The signal is
delivered according to the semantics of described above.
The fcntl(2) and flags (defined in are supported by sockets. If the flag is set, the socket is put into POSIX-style non-blocking mode. If
the flag is set, the socket is put into non-blocking mode. Otherwise, the socket is put into blocking mode. Blocking mode is the default.
See accept(2), connect(2), recv(2), and send(2) for an explanation of how these forms of non-blocking mode are used.
Since the and flags and requests are supported, the following clarifies on how these features interact. If the or flag has been set, and
requests behave accordingly, regardless of any requests. If neither the flag nor the flag has been set, requests control the the behavior
of and
DEPENDENCIES
AF_CCITT Only
Only the and requests are defined for sockets.
AUTHOR
was developed by the University of California, Berkeley.
SEE ALSO
fcntl(2), getsockopt(2), ioctl(2), socket(2).
socket(7)