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This chapter describes the GNU facilities for interprocess communication using sockets.
A socket is a generalized interprocess communication channel.
Like a pipe, a socket is represented as a file descriptor. Unlike pipes
sockets support communication between unrelated processes, and even
between processes running on different machines that communicate over a
network. Sockets are the primary means of communicating with other
machines; telnet
, rlogin
, ftp
, talk
and the
other familiar network programs use sockets.
Not all operating systems support sockets. In the GNU C Library, the header file sys/socket.h exists regardless of the operating system, and the socket functions always exist, but if the system does not really support sockets these functions always fail.
Incomplete: We do not currently document the facilities for broadcast messages or for configuring Internet interfaces. The reentrant functions and some newer functions that are related to IPv6 aren’t documented either so far.
• Socket Concepts | Basic concepts you need to know about. | |
• Communication Styles | Stream communication, datagrams and other styles. | |
• Socket Addresses | How socket names (“addresses”) work. | |
• Interface Naming | Identifying specific network interfaces. | |
• Local Namespace | Details about the local namespace. | |
• Internet Namespace | Details about the Internet namespace. | |
• Misc Namespaces | Other namespaces not documented fully here. | |
• Open/Close Sockets | Creating sockets and destroying them. | |
• Connections | Operations on sockets with connection state. | |
• Datagrams | Operations on datagram sockets. | |
• Inetd | Inetd is a daemon that starts servers on request. The most convenient way to write a server is to make it work with Inetd. | |
• Socket Options | Miscellaneous low-level socket options. | |
• Networks Database | Accessing the database of network names. |
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