Signals
Asynchronous notifications.
What Is a Signal
A signal is an asynchronous notification sent to a process to tell it that an event occurred, such as a user pressing Ctrl-C or a child process exiting. Signals are a lightweight form of IPC.
Common Signals
A few you will meet often:
SIGINTinterrupt (Ctrl-C)SIGTERMpolite termination requestSIGKILLforced kill (cannot be caught)SIGCHLDa child changed stateSIGSEGVinvalid memory access