kill(1posix) - terminate or signal processes
-l     (The  letter  ell.) Write all values of signal_name supported by the implementation, if no operand
       is given. If an exit_status operand is given and it is a value of the '?'  shell special parameter
       (see  Special  Parameters and wait() ) corresponding to a process that was terminated by a signal,
       the signal_name corresponding to the signal that terminated the process shall be written.   If  an
       exit_status  operand is given and it is the unsigned decimal integer value of a signal number, the
       signal_name (the symbolic constant name without the SIG prefix defined  in  the  Base  Definitions
       volume  of  IEEE Std 1003.1-2001)  corresponding  to  that signal shall be written. Otherwise, the
       results are unspecified.

-s  signal_name

       Specify the signal to send, using one of the symbolic names  defined  in  the  <signal.h>  header.
       Values  of  signal_name shall be recognized in a case-independent fashion, without the SIG prefix.
       In addition, the symbolic name 0 shall be recognized, representing  the  signal  value  zero.  The
       corresponding signal shall be sent instead of SIGTERM.
-signal_name

       Equivalent to -s signal_name.
-signal_number