This Linux signals reference lists the common process signals and their numbers — used with the kill command. For example kill -9 sends SIGKILL to force-stop a process.
| Signal | Number | Meaning |
|---|---|---|
| SIGHUP | 1 | Hangup / reload config |
| SIGINT | 2 | Interrupt (Ctrl+C) |
| SIGQUIT | 3 | Quit (Ctrl+\) |
| SIGILL | 4 | Illegal instruction |
| SIGKILL | 9 | Kill immediately (cannot be caught) |
| SIGSEGV | 11 | Segmentation fault |
| SIGPIPE | 13 | Broken pipe |
| SIGALRM | 14 | Timer alarm |
| SIGTERM | 15 | Terminate gracefully (default kill) |
| SIGCHLD | 17 | Child stopped or exited |
| SIGCONT | 18 | Continue if stopped |
| SIGSTOP | 19 | Stop (cannot be caught) |
| SIGTSTP | 20 | Stop from terminal (Ctrl+Z) |