#include "main.h"

//======================================================================
int main(int argc, char **argv)
{
  int ok;
  char *sort_args[] = {"sort",  NULL};

  // open input and output files
  int fdIn = open("animals", O_RDONLY);
  						 if(fdIn < 0) { perror("open"); return 1; }
  int fdOut = open("results", O_WRONLY | O_TRUNC | O_CREAT, S_IRUSR | S_IRGRP | S_IWGRP | S_IWUSR);
						 if(fdOut < 0) { perror("open"); return 1; }

  // replace standard input with input file
  ok = dup2(fdIn,0); 		// 0 = stdin
						if(ok == -1) { perror("dup2"); return 1; } 
  
  // replace standard output with output file
  ok = dup2(fdOut,1); 	// 1 =stdout
						if(ok == -1) { perror("dup2"); return 1; }

  // close unused file descriptors
  ok = close(fdIn);
  						if(ok == -1) { perror("close"); return 1; } 
  ok = close(fdOut);
  						if(ok == -1) { perror("close"); return 1; } 

  // execute sort
  ok = execvp("sort", sort_args);	// Default case : execvp read from stdin, write on stdout
						if(ok == -1) { perror("execvp"); return 1; } 
			
return 0;
}
//^^^^^^^^^^^^^^^^^^^^^^^^^^ EOF ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^