in reply to Open, ye! And read from your child!

Along with having buffering on, your <READ> is in list context, sucking up all input, which doesn't appear to be what you want. Try this:
$|++;

if (my $pid = open(READ, "-|")) {
  my $line = <READ>;
  print "child said: [", $line, "]; ",time,"\n";
  $line = <READ>;
  print "child said: [", $line, "]; ",time,"\n";
} else {
  print "hello; ",time,"\n";
  sleep 2;
  print "how are you; ",time,"\n";
}

[download]

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Re: Re: Open, ye! And read from your child!
by gryng (Hermit) on Nov 13, 2001 at 01:42 UTC

    Doh! You would think a (relatively) seasoned Perl Junkie would have noticed that list context blurp. Ok the new code that works is:

    #!/usr/bin/perl -w
use strict;

if (my $pid = open(READ, "-|")) {
  print "child said: '", scalar <READ>, "'; ",time,"\n";
  print "child said: '", scalar <READ>, "'; ",time,"\n";
} else {
  $|=1;
  print "hello; ",time,"\n";
  sleep 2;
  print "how are you; ",time,"\n";
}

    [download]
    And output: 
    gryn@echor:~$ ./testcase.pl
child said: 'hello; 1005597768
'; 1005597768
child said: 'how are you; 1005597770
'; 1005597770

    [download]

    The buffering is necessary, as you all pointed out. However, with the list context problem in the way, I couldn't figure out where to properly put the (de)buffering until it was fixed.

    Thanks and kudos to you three,
    Gryn
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