#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/file.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>


int main()
{
    int descriptor = creat("tekst2.txt",0600);

    pid_t pid;
    flock(descriptor,LOCK_SH );
    pid = fork();

    if(pid == 0)
    {

        char string_2[] = "POTOMNY PISZE\n";
        sleep(3);
        lseek(descriptor,0,SEEK_SET);
        write(descriptor,(void *)string_2,sizeof(string_2)-1);

        _exit(0);
    }
    else
    {
        char string_1[] = "RODZIC PISZE\n";
        lseek(descriptor,0,SEEK_SET);
        write(descriptor,(void*)string_1,sizeof(string_1)-1);
    }

    close(descriptor);

    return 0;
}