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

#define MAX_INPUT_SIZE 1024
#define MAX_TOKEN_SIZE 64
#define MAX_NUM_TOKENS 64

/* Splits the string by space and returns the array of tokens
*
*/
char **tokenize(char *line)
{
  char **tokens = (char **)malloc(MAX_NUM_TOKENS * sizeof(char *));
  char *token = (char *)malloc(MAX_TOKEN_SIZE * sizeof(char));
  int i, tokenIndex = 0, tokenNo = 0;

  for(i =0; i < strlen(line); i++){

    char readChar = line[i];

    if (readChar == ' ' || readChar == '\n' || readChar == '\t'){
      token[tokenIndex] = '\0';
      if (tokenIndex != 0){
	tokens[tokenNo] = (char*)malloc(MAX_TOKEN_SIZE*sizeof(char));
	strcpy(tokens[tokenNo++], token);
	tokenIndex = 0; 
      }
    } else {
      token[tokenIndex++] = readChar;
    }
  }
 
  free(token);
  tokens[tokenNo] = NULL ;
  return tokens;
}


int main(int argc, char* argv[]) {
	char  line[MAX_INPUT_SIZE];            
	char  **tokens;              
	int i;


	while(1) {			
		/* BEGIN: TAKING INPUT */
		bzero(line, sizeof(line));
		printf("$ ");
		scanf("%[^\n]", line);
		getchar();

		printf("Command entered: %s (remove this debug output later)\n", line);
		/* END: TAKING INPUT */
		
		line[strlen(line) - 1] = '\n'; //terminate with new line
		tokens = tokenize(line);
		
		if(strcmp(tokens[i], "exit") == 0){
			break;		
		}
		
		if(strcmp(tokens[0], "ls") == 0){
				char *args[2];
				args[0] = "/bin/ls";
				args[1] = NULL;
				
				int rc = fork();
				if(rc<0){printf("Fork failed");}
				else if(rc==0){
					execv(args[0], args);
					exit(1);
				}
				else{
					int w = wait(NULL); printf("Success!\n");
				}
				break;
		}

      		for(i = 0; tokens[i] != NULL; i++){
			
		}

		for(i=0;tokens[i]!=NULL;i++){
			printf("found token %s (remove this debug output later)\n", tokens[i]);
		}
       
		// Freeing the allocated memory	
		for(i=0;tokens[i]!=NULL;i++){
			free(tokens[i]);
		}
		free(tokens);

	}
	return 0;
}