Here you go

#include <iostream>
#include <csignal>
#include <unistd.h>

void sigusr1_handler(int signal)
{
	std::cout << "Signal USR1" << std::endl;
}

int main()
{
	std::cout << "Installed handler for USR1" << std::endl;
	std::signal(SIGUSR1, sigusr1_handler);
	while (1 == 1)
	{
		usleep(5000000);	// 5 seconds
		std::cout << "Waiting for signal" << std::endl;
	}
}

That will help you read at least one of them.