myprog1 &
myprog2 &
wait
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Since Perl lets me actually open these as pipes so I can read their output (instead of having the programs write a file) I thought I'd try it using Perl. I'm doing something like this (error checking removed for brevity):

  my $pid1 = open(PIPE1, "myprog1|");
  my $pid2 = open(PIPE2, "myprog2|");
  while ($pid1 >= 0 || $pid2 >= 0) {
    my $pid = wait;
    if ($pid == $pid1) {
      print "myprog1 completed.\n";
      $pid1 = -1;
    } elsif ($pid == $pid2) {
      print "myprog2 completed.\n";
      $pid2 = -1;
    }
  }
  my $output1 = <PIPE1>;  # this works (I see the output of "myprog1")
  my $output2 = <PIPE2>;  # this works as well
  close PIPE1;  # this fails!
  close PIPE2;  # this fails as well!
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Why does the close fail? The help for "close" indicates that an implicit wait is done on the piped process before the close returns -- does the same thing happen if an explicit "wait" is done first? If so, how does the reading of the pipes (i.e. <PIPE1> and <PIPE2>) work if the file has been closed? Does Perl maintain the output of the program somewhere? It seems weird that you can read from something that you can't close. Am I missing something here? Thanks.