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Asynchronous I/O Signals

The signals listed in this section are used in conjunction with asynchronous I/O facilities. You have to take explicit action by calling fcntl to enable a particular file descriptior to generate these signals (see section Interrupt-Driven Input). The default action for these signals is to ignore them.

Macro: int SIGIO

This signal is sent when a file descriptor is ready to perform input or output.

On most operating systems, terminals and sockets are the only kinds of files that can generate SIGIO; other kinds, including ordinary files, never generate SIGIO even if you ask them to.

Macro: int SIGURG

This signal is sent when "urgent" or out-of-band data arrives on a socket. See section Out-of-Band Data.

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