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24.4 Defining Signal Handlers

This section describes how to write a signal handler function that can be established with the signal or sigaction functions.

A signal handler is just a function that you compile together with the rest of the program. Instead of directly invoking the function, you use signal or sigaction to tell the operating system to call it when a signal arrives. This is known as establishing the handler. See Specifying Signal Actions.

There are two basic strategies you can use in signal handler functions:

You need to take special care in writing handler functions because they can be called asynchronously. That is, a handler might be called at any point in the program, unpredictably. If two signals arrive during a very short interval, one handler can run within another. This section describes what your handler should do, and what you should avoid.