kill signal
1
SIGHUP
-1
Hang up – often used to reload config files. Example: kill -1 <pid> for Nginx reload.
2
SIGINT
-2
Interrupt – same as pressing Ctrl+C. Used to gracefully stop foreground processes.
3
SIGQUIT
-3
Quit and dump core – like Ctrl+\, used for debugging.
9
SIGKILL
-9
Force kill – immediate termination, no cleanup. Use only when graceful shutdown fails.
15
SIGTERM
-15
Default signal for kill. Asks process to terminate gracefully.
18
SIGCONT
-18
Continue a paused process (resumes from SIGSTOP).
19
SIGSTOP
-19
Pause the process (like Ctrl+Z in terminal). Can’t be ignored.
20
SIGTSTP
-20
Terminal stop (Ctrl+Z) – suspends the process in foreground.
10
SIGUSR1
-10
User-defined signal 1 – applications can handle it for custom purposes.
12
SIGUSR2
-12
User-defined signal 2 – also for application-specific behavior.