The kill(1) command

The kill(1) command is used for either terminating a process or sending a less cruel signal to it. Keep in mind that the fact that you can send a signal to a process does not mean that the process can or has code to handle this signal.

By default, kill(1) sends the SIGTERM signal. If you want to find out all the supported signals of your Unix machine, you should execute the kill -l command. On a macOS Sierra machine, the output of kill -l is the following:

$ kill -l1) SIGHUP   2) SIGINT        3) SIGQUIT   4) SIGILL5) SIGTRAP  6) SIGABRT       7) SIGEMT    8) SIGFPE9) SIGKILL 10) SIGBUS        11) SIGSEGV 12) SIGSYS13) SIGPIPE 14) SIGALRM       15) SIGTERM 16) SIGURG17) SIGSTOP 18) SIGTSTP       19) SIGCONT 20) SIGCHLD21) SIGTTIN 22) SIGTTOU       23) SIGIO   24) SIGXCPU25) SIGXFSZ 26) SIGVTALRM     27) SIGPROF 28) SIGWINCH29) SIGINFO 30) SIGUSR1       31) SIGUSR2

If you execute the same command on a Debian Linux machine, you will get a more enriched output:

$ kill -l1) SIGHUP...