| Signal | Number | Meaning | Common Usage |
|---|---|---|---|
SIGTERM | 15 | Graceful termination | kill PID (default) |
SIGKILL | 9 | Immediate kill (cannot be caught) | kill -9 PID |
SIGINT | 2 | Interrupt from keyboard (Ctrl+C) | Stops foreground process |
SIGTSTP | 20 | Terminal stop (Ctrl+Z) | Suspend process |
SIGHUP | 1 | Hangup / restart signal | Restart daemons |
SIGCHLD | 17 | Child stopped/terminated | Used by parents to reap zombies |
SIGCONT | 18 | Continue if stopped | After SIGSTOP/SIGTSTP |
SIGSTOP | 19 | Stop (cannot be ignored) | Like SIGTSTP but unconditional |