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']});

    In reply to Re^2: Best practice ipc and Log::Log4perl by codeacrobat
    in thread Best practice ipc and Log::Log4perl by codeacrobat

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