// threads using pipe
//
#include <stdio.h>
#include <pthread.h>
#include <unistd.h> // for sleep() and pipe()
#include <stdlib.h> // for exit()

#define EXIT(msg) { perror(msg); exit(1); }

#define Pthread_create(a,b,c,d) if( pthread_create(a,b,c,d) ) EXIT("pthread_create")

#define Pipe(a) if( pipe(a) ) EXIT("pipe")

#define NT 4 // number of threads

int count[NT] = { 5, 4, 3, 2 };

void *f( void *v)
{
  int *p = v;

  while( *p > 0) { sleep(1); --*p; } // slowly decrement my counter

  printf( "Done\n"); fflush(stdout);

  return 0;
}

int main( void)
{
  pthread_t t[NT];

 // redirect stdin and stdout through pipe
 //
  int fd[2]; Pipe(fd); dup2(fd[0],0); dup2(fd[1],1); close(fd[0]); close(fd[1]);

 // create the threads
 //
  for( int i = 0; i < NT; ++i)
    Pthread_create( &t[i], 0, f, &count[i]);

 // wait until any one thread is finished
 //
  char line[BUFSIZ];
  (void) !fgets( line, BUFSIZ, stdin); // ignore fgets() return value

 // stop all threads
 //
  for( int i = 0; i < NT; ++i) pthread_cancel( t[i]);
}