Currently the following signals are used with alert and drop:
SIGINTCancels the program, the socket and PID file are
removed and the program exits. The program drop
prints all buffered alerts, either via stdout or
syslog, see option -l or keyword Syslog, before it
exits.
SIGTERMThis signal
results in the same behaviour as SIGINT.
SIGHUP[3]If this signal is received the unix domain socket will be closed, the socket and PID file removed and thre porgram gets restarted. The program drop prints first all buffered alerts.
SIGALRMThis signal is used to print statistics on a periodically basis. If this signal is send to the master process it is forwarded to all child processes.