#include <stdio.h> 
#include <unistd.h> 

#define BUFFSIZE 1024

int main () 
{ 
	// creates a pipe and changes it to a file pointer
	// only works one way.
	char buffer[BUFFSIZE];
	FILE* stream;
	int rval;
	stream = popen ("sort", "w");
 
	fprintf (stream, "This is a test.\n");
	fprintf (stream, "Hello, world.\n");
	fprintf (stream, "My dog has fleas.\n");
	fprintf (stream, "This program is great.\n");
	fprintf (stream, "One fish, two fish.\n");

	pclose (stream);

	stream = popen ("ls", "r");
	while((rval = fread(buffer, 1, BUFFSIZE, stream)) > 0) {
		printf("fread returned %d\n",rval);
		fwrite(buffer,1,rval,stdout);
	}
	pclose (stream);
 }