Signal handling

A signal is used in UNIX systems to inform a process that a particular event has occurred.

1. A signal is produced by the occurrence of a particular event.

2. A generated signal is delivered to a process.

3. Once delivered, the signal must be handled.

Each signal may be handled by one of two possible handlers

1. A default signal handler.

2. A user-defined signal handler.

Each signal has a default signal handler that is run by the kernel when handling the signal. This default action might be overridden by user-defined signal handler function.