Pipe demo

pipe.sh

gcc -x c++ -o test_read - << EOF
#include <stdio.h>
#include <unistd.h>

int main()
{
  fprintf(stdout, "[[Read begin]]\n");
  for (int j=0; j<20; j++)
  {
    fprintf(stdout, "[[Read Block %d]]\n", j);
    usleep(500*1000);
    // Read 1 MB of data, show first 20 characters
    for (int r=0; r<1024; r++)
    {
      for (int i=0; i<1024; i++)
      {
        int c = fgetc(stdin);
        if (r==0 && i<20) printf("%c", c);
     }
   }
  }
  fprintf(stdout, "[[Read Done]]\n");
  return 0;
}
EOF

gcc -x c++ -o test_write - << EOF
#include <stdio.h>

int main()
{
  fprintf(stderr, "Write begin\n");
  for (int b=0; b<200; b++)
  {
    fprintf(stderr, "Write Block %d, ", b);
    // Write 1MB of data
    for (int i=0; i<1024; i++)
    {
      printf("%08d-%08d:", b, i);
      for (int k=0; k<1024-20; k++)
        printf(" ");
      printf("\r\n");
    }
  }
  fprintf(stderr, "Write done\n");
  return 0;
}
EOF

./test_write | ./test_read


exit 0

Expected output ("Write done" never reached):

Write begin
Write Block 0, [[Read begin]]
[[Read Block 0]]
Write Block 1, 00000000-00000000:  [[Read Block 1]]
Write Block 2, 00000001-00000000:  [[Read Block 2]]
Write Block 3, 00000002-00000000:  [[Read Block 3]]
Write Block 4, 00000003-00000000:  [[Read Block 4]]
Write Block 5, 00000004-00000000:  [[Read Block 5]]
Write Block 6, 00000005-00000000:  [[Read Block 6]]
Write Block 7, 00000006-00000000:  [[Read Block 7]]
Write Block 8, 00000007-00000000:  [[Read Block 8]]
Write Block 9, 00000008-00000000:  [[Read Block 9]]
Write Block 10, 00000009-00000000:  [[Read Block 10]]
Write Block 11, 00000010-00000000:  [[Read Block 11]]
Write Block 12, 00000011-00000000:  [[Read Block 12]]
Write Block 13, 00000012-00000000:  [[Read Block 13]]
Write Block 14, 00000013-00000000:  [[Read Block 14]]
Write Block 15, 00000014-00000000:  [[Read Block 15]]
Write Block 16, 00000015-00000000:  [[Read Block 16]]
Write Block 17, 00000016-00000000:  [[Read Block 17]]
Write Block 18, 00000017-00000000:  [[Read Block 18]]
Write Block 19, 00000018-00000000:  [[Read Block 19]]
Write Block 20, 00000019-00000000:  [[Read Done]]