Sorry I dont quite follow, if you want to make your program run quietly then just dont print anything to stdout??!! Could you not just concat any messages to an internal variable instead of printing. If you really want to

Do you mean that you want to capture stdout/stderr of a program that you fork? If that is the case then you could connect the child process to the parent via pipes and capture the op directly from the pipes (see below).

If you really want to capture stdout in this way you could wrap the program in a fork as in this incomplete example.

if ($pid = open(CHILD,"-|"))
{
  while (<CHILD>)
  {
    $data .= $_;
  } 
  print $data;
} else
{
  exec ("ls");
}
[download]