//need two element int array for pipe
int pd[2];

//make pipe before child processes are made so every child writes to this one pipe
if(pipe(pd) == -1)
 44     {
 45       error_exit("pipe");
 46     }

//NOTE: each pid = fork() is a new child process, so if in a loop
//you will have n child process that the parent should wait on before
//reading from the pipe, null reads make the program hang up
if((pid = fork()) == 0)
 63       {
 64         fp = fopen(cp, "r");
 65
 66         if(fp == NULL)
 67         {
 68           fprintf(stderr, "%s: unable to read %s\n", pgname, cp);
 69           exit(1);
 70         }
 71
 72         // print current file (argv[i]) just for sanity, remove after testing
 73         printf("%s\n", argv[i]);
 74         printf("pid = %d\n", pid);
 75
 76         count(fp);
 77
 78         //write to pipe
 79         //order is line, word, byte, filename, child pid!
 80
        //note pd[1] is passed to write, this is always what you pass
 81         if(write(pd[1], &words, MSGSIZE) == -1)
 82         {
 83           error_exit("write words failed");
 84         }
 85         if(write(pd[1], &lines, MSGSIZE) == -1)
 86         {
 87           error_exit("write lines  failed");
 88         }
 89         if(write(pd[1], &bytes, MSGSIZE) == -1)
 90         {
 91           error_exit("write bytes failed");
 92         }
 93         return; //return from child statement
 94       }

//wait for all child process to end before continuing
 98     while((wpid = wait(NULL)) > 0);

//parent can read pipe now
101
102     int temp = 0;
103     char fname[MSGSIZE];
        //numberOfWritesToPipe needs to match number of times a child process wrote to the pipe
    //for example, wrote lines, writes, bytes, and file name from child process, so read pipe 4 times
    int numberOfWritesToPipe = 4;
104     for(i = 0; i < numberOfWritesToPipe; i++)
105     {
106       if(i < 3)
107       {
        //notice pd[0] passed to write, this is always the case
108         if((read(pd[0], &temp, sizeof(temp))) == -1)
109         {
110           error_exit("read failed (digit)");
111         }
112         switch(i)
113         {
114           case 0:
115             bytes += temp;
116             break;
117           case 1:
118             words += temp;
119             break;
120           case 2:
121             lines += temp;
122             break;
123         }
124       }
125       else
126       {
127         if((read(pd[0], buf, MSGSIZE)) == -1)
128         {
129           error_exit("read failed (string)");
130         }
131         printf("file name?? %s\n", buf);//figure out why this is failing
 132       }
133     }