#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <errno.h>
#include <sys/wait.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>

main(int argc, char *argv[])
{
    pid_t waitpid, childpid;
    int fh1;
    int status;
    fh1 = open(argv[1], O_RDONLY);//проверка тебе вроде как не нужна
    if (fh1 == -1)
    {
        printf(" invalid filename\n");
        return -1;
    }
    else
    {
        printf(" file exists\n");
    }
    childpid=fork();
    if(childpid==0)
        {
            /*Child's code*/
            printf("waiting 5 sec \n");
            sleep(5);
            //execv(argv[1],argv);
            //твой код
        }
    waitpid=wait(&status);
    printf("waitpid %d\n", waitpid);
    printf("status %d\n", status);
    if(WIFEXITED(status)==1)
    {
        printf(" child ended normally with WEXITSTATUS=%d\n",WEXITSTATUS(status));
    }
    else
    {
        printf(" child ended not normally\n");
    }
    return;
}