#include<stdio.h>
#include<sys/types.h>
#include<sys/mman.h>
#include<stdlib.h>
#include<fcntl.h>
#include<sys/stat.h>
#include<unistd.h>
#include<signal.h>
#include<string.h>

main(int argc, char *argv[])
{
        int fd,changes,i,random_spot,kids[2];
        struct stat buf;
        char *the_file,*starting_string="Finally got it! \n";
        size_t length=strlen(the_file);

size_t starting=strlen(starting_string);
if (argc!=2)
{
fprintf(stderr, "Usage %s file_name \n",*argv);
exit(1);
}
if((fd=open(argv[1], O_CREAT | O_RDWR,0666))<0)
{
fprintf(stderr,"open error on file %s\n",*argv);
exit(3);
}
write(fd,starting_string,starting);
if(fstat(fd,&buf)<0)
{
fprintf(stderr,"fstat error on file %s\n",*argv);
exit(4);
}
if((the_file=mmap(0,(size_t)
buf.st_size,PROT_READ|PROT_WRITE,MAP_SHARED,fd,0))==(caddr_t)-1)

{
fprintf(stderr,"mmap failure\n");
exit(5);
}

for(i=0;i<length;++i)
{
if(*(the_file+i)>='0' && *(the_file+i)<='9')
*(the_file+i)='*';
sleep(1);
}

printf("Parent done with changes\n");
 printf("The file now contains:\n%s\n",the_file);

exit(0);
}