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Unformatted text preview: means writing an image of the code and data memory segments to disk. 8.5. SIGNALS 423 8.5.1 Signal Terminology
The transfer of a signal to a destination process occurs in two distinct steps: ¯ Sending a signal. The kernel sends (delivers) a signal to a destination process by updating some state in the context of the destination process. The signal is delivered for one of two reasons: (1) the kernel has detected a system event such as a divide-by-zero error or the termination of a child process; (2) A process has invoked the kill function (discussed in the next section) to explicitly request the kernel to send a signal to the destination process. A process can send a signal to itself. Receiving a signal. A destination process receives a signal when it is forced by the kernel to react in some way to the delivery of the signal. The process can either ignore the signal, terminate, or catch the signal by executing a user-level function called a signal handler. ¯ A signal that has been sent but not yet received is called a pending signal. At any point in time, there can be at most one pending signal o...
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This note was uploaded on 09/02/2010 for the course ELECTRICAL 360 taught by Professor Schultz during the Spring '10 term at BYU.
- Spring '10
- The American