1.6.6. Signals and Interprocess Communication
Unix signals provide a mechanism for notifying processes of system events. Each event has its own signal number, which is usually referred to by a symbolic constant such as SIGTERM
. There are two kinds of system events:
Asynchronous notifications
For instance, a user can send the interrupt signal SIGINT
to a foreground process by pressing the interrupt keycode (usually Ctrl-C) at the terminal.
Synchronous notifications
For instance, the kernel sends the signal SIGSEGV
to a process when it accesses a memory location at an invalid address.