What Are Signals?
Definition
Signals are generated when an event occurs that requires
attention. It can be thought of as a software version of a hardware
interrupt.
Definition
Signals can be generated from the following sources:
- Hardware
Example: division by zero, address protection
- System Kernel
Example: notifying an I/O device for which
a process has been waiting is available.
- Other Processes
Example: a child process notifying its
parent process that it has terminated.
- User
Example: pressing a keyboard sequences that generate
a quit, interrupt or stop signal.