#include <stdio.h>
#include <sys/wait.h>
#include <unistd.h>
#include <ctype.h>
#include <string.h>
#include <stdlib.h>

int main(int argc, char **argv){
   int pid;
   if(!(argc >= 4 && (strcmp(argv[1], "stdout") == 0 ||
       strcmp(argv[1], "stdin") == 0 ||
       strcmp(argv[1], "stderr") == 0))) {
      printf("Usage:\n");
      printf("\t redir {stdout | stdin | stderr} file program [args]\n");
      return -1;
   }

   int i;
   char* forkArgs[100];

   for(i = 3; i < argc; i++){
      forkArgs[(i - 3)] = argv[i];
   }

   pid = fork();

   if(pid == 0){
      if(strcmp(argv[1], "stdout") == 0){
         freopen(argv[2], "w+", stdout);
      }else if(strcmp(argv[1], "stdin") == 0){
         freopen(argv[2], "r", stdin);
      }else{
         freopen(argv[2], "w+", stderr);
      }
      execvp(argv[3], forkArgs);
      _exit(0);
   }else if(pid > 0){
      wait(0);
   }else{
      printf("couldn't fork a child");
      return 1;
   }
   return 0;
}