Understanding Unix Signals
Understanding Unix Signals
Signals are asynchronous software interrupts sent to a process by the kernel or other processes:
| Signal | Number | Default Action | Description | Catchable? |
|---|---|---|---|---|
SIGHUP |
1 | Terminate | Terminal hangup or daemon reload | Yes |
SIGINT |
2 | Terminate | Keyboard interrupt (Ctrl+C) | Yes |
SIGQUIT |
3 | Core Dump | Keyboard quit (Ctrl+) | Yes |
SIGKILL |
9 | Immediate Terminate | Hard kernel uncatchable kill | No |
SIGTERM |
15 | Terminate | Polite request to gracefully terminate | Yes |
SIGUSR1/SIGUSR2 |
10/12 | Terminate | User-defined custom hooks | Yes |