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How to write a signal handler

The signal handler is a function that gets called when the process receives a signal. The function is called in asynchronous mode, meaning that no where in the program you have code that calls this function directly. When your signal handler returns (assuming it doesn't call exit or longjmp or something that prevents it from actually returning), the code will continue at the point the signal occurred, reexecuting the same instruction.

Modern Signal Handling. It is the 2013th year in the Common Era at the moment of this writing and you might think that people should have came up with something better in terms of signal handling at this time.

The truth is that they did. It is just not that well known yet due to a huge momentum of outdated information still overflowing the Internet. How to write a signal handler function. Interrupted Primitives: Signal handlers affect use of open, read, write and other functions. Generating Signals: How to send a signal to a process. Blocking Signals: Making the system hold signals temporarily. Waiting for a Signal: Suspending your program until a signal arrives. After reading these comments and the signal man pages it seems multiple people say that using printf in a signal handler is a bad idea, but not why.

Could someone elaborate? Could someone elaborate? This comment has been minimized. 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.

In practice it means that receiving a signal is an edge, and in signal handler you must check how many times the signal occurred. This for Installing a Signal Handler. The first step is to declare a signal handling routine. There are two kinds of signal handling routines: one kind that does not take any parameters and another kind that takes a set of three parameters. The parameters are necessary if the objective is to extract information from the current state of the application.