Examole of handling signals (Linux)

#include <unistd.h>
#include <stdio.h>
#include <signal.h>
#include <ncurses.h>
#include <stdlib.h>
#include <termios.h>
#include <sys/ioctl.h>
#include <string.h>


int  _kbhit() {
    static bool inited = false;
    int left;

    if (!inited) {
        struct termios t;
        tcgetattr(0, &t);
        t.c_lflag &= ~ICANON;
        tcsetattr(0, TCSANOW, &t);
        setbuf(stdin, NULL);
        inited = true;
    }

    ioctl(0, FIONREAD, &left);

    return left;
}

void handle_sigusr1(int sig)
{
    fflush(stdout);
    system("date");
    FILE *f = fopen("text.txt", "a");
    if(f == NULL)
    {
        printf("Error while opening file\n");
        return;
    }
    char *str = (char *)malloc(sizeof(char) * 256);
    strcpy(str, "aaa");
    for(int i = 0; i<3; i++)
    {
        str[i] = 'a' + rand()%26;
    }
    fprintf(f,"%s\n", str);
    fclose(f);
}

int main()
{
    int pid = fork();
    switch (pid)
    {
    case -1:
        printf("Error launchong mew proces\n");
        break;
    case 0:
    {
        while (true)
        {
            sleep(2);
            kill(getppid(), SIGUSR1);
        }
    }

    default:
    {
        struct sigaction sa;
        //gsa.sa_flags = SA_RESTART;
        sa.sa_handler = &handle_sigusr1;
        sigaction(SIGUSR1, &sa, NULL);
        while (true)
        {
            if(_kbhit() != 0)
            {
                kill(pid, SIGKILL);
                return 0;
            }
        }
    }
        break;
    }
}