test.c

#define _POSIX_C_SOURCE 200809l
                                                                                                                    
#include <signal.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>

static void handler(int signum)
{
}

int main(void)
{
    sigaction(SIGUSR1, &(const struct sigaction){ .sa_handler = handler }, NULL);

    pid_t child = fork();
    if (!child) {
        sleep(1);
        kill(getppid(), SIGUSR1);
        sleep(5);
    } else {
        int status = 0;
        pid_t ret = waitpid(child, &status, 0);
        if (ret < 0) {
            perror("waitpid failed");
        } else {
            printf("(%i, %i)\n", (int)ret, status);
        }
    }

    return 0;
}