Could you be more specific as to what you want to do that IPC::Open3, IPC::Run3, Tie::STDOUT, Tie::STDERR don't do? I don't understand.

What I want:
• read unbuffered from a child process ( long running process ).
• capture childprocess stderr & stdout separately
• write the childprocess stdout and stderr stream to a logfile and tag lines with a <timestamp> and a tag <INFO> or <ERROR> depending on the source stream.
IPC::Run3 almost does what I need.

#!/usr/bin/perl
# timestamp.pl
$|++;
while(time - $^T<10){
  select undef,undef,undef, 0.1;
  if ( rand()<0.5) {
    print STDERR  time(),  " warn\n";
  } else {
    print time(), " info\n";
  }
}
__END__
[download]

use IPC::Run3 qw(run3);
my @cmd = ('perl', 'timestamp.pl');
run3 \@cmd, undef, \&out, \&err;
sub out {
  print time(), " out: $_\n";
}
sub err {
  print time(), " err: $_\n";
}
__END__
# The problem is that run3 buffers the output.
1215162770 out: 1215162760 info
1215162770 out: 1215162760 info
1215162770 out: 1215162761 info
1215162770 out: 1215162761 info
1215162770 out: 1215162761 info
1215162770 out: 1215162761 info
1215162770 out: 1215162762 info
1215162770 out: 1215162762 info
1215162770 out: 1215162762 info
1215162770 out: 1215162763 info
[download]

---

print+qq(\L@{[ref\&@]}@{['@'x7^'!#2/"!4']});

Run3 apparently doesn't do concurrency. IPC:Run can be made to do what you want. This works:

#!/usr/bin/perl
 # timestamp.pl
while(time - $^T<10){
select undef,undef,undef, 0.1;
if ( rand()<0.5) {
    print STDERR time(), " warn\n";
} else {
    print time(), " info\n"; }
}
print "end\n";
__END__

use IPC::Run qw ( start pump finish timeout );
my $in;
my $out;

my @cmd = qw( perl timestamp.pl);

## Build the harness, open all pipes, and launch the subprocesses
   my $h = start \@cmd, \$in, \$out, \$out ;
   $in = "" ;

   ## Now do I/O.  start() does no I/O.
   pump $h while length $in ;  ## Wait for all input to go

   ## Now do some more I/O.
   while (1){
       pump $h until $out =~ s/(.+)\n$//gm ;
       last if ("end" eq $1);
        print time, " : $1\n";
    }

   ## Clean up
   finish $h or die "cat returned $?" ;
__END__

1215226647 : 1215226647 info
1215226647 : 1215226647 info
1215226647 : 1215226647 warn
1215226647 : 1215226647 info
1215226647 : 1215226647 warn
1215226647 : 1215226647 warn
1215226647 : 1215226647 info
1215226647 : 1215226647 info
1215226647 : 1215226647 info
1215226648 : 1215226648 warn
[download]

---

s//----->\t/;$~="JAPH";s//\r<$~~/;{s|~$~-|-~$~|||s |-$~~|$~~-|||s,<$~~,<~$~,,s,~$~>,$~~>,, $|=1,select$,,$,,$,,1e-1;print;redo}