SIGNALS:
Here follows a list of supported signals and their meaning; note: pmacct core
process says goodbye when its last child dies or is terminated.


Core process:
SIGCHLD:	used to handle gracefully his loved child processes;
SIGHUP:         reopens the logging infrastructure. Works with both syslog
		and logfiles;
SIGUSR1:        returns various statistics via either console or syslog; the
		syslog level used is NOTICE; the facility is selected through
		configuration (ie. key 'syslog'). The feature works for all
		daemons;
SIGUSR2:	if 'refresh_maps' config directive is enabled, it causes Core
		Process-based maps to be reloaded (ie. Pre-Tagging, BGP source
		peer ASN, NetFlow/sFlow agent to BGP peer, BGP MD5, etc.).
SIGINT:		ignored if the daemon is started in background; otherwise the
		signal is propagated to each running plugin (which is in turn
		gracefully terminated);
SIGTERM:	not handled (which means it follows the default behaviour for
		the OS) if the daemon is started in background; otherwise it 
		orks like SIGINT;
SIGPIPE:	ignored;

Plugin (SQL, noSQL, memory, print, tee, probes, etc.) processes:
SIGPIPE:	ignored;
SIGCHLD:	ignored;
SIGHUP:		inherited by Core Process; 
SIGUSR1:	ignored;
SIGUSR2:        if 'refresh_maps' configuration directive is enabled it causes
		Ports and Networks maps to be reloaded;
SIGINT:		causes the process to exit gracefully;	
