# controlled search-and-replace to insert column markers
# using the header line as a guide to where the columns lie

$headers = <>;
$headers =~ s/(\S)\s/$1\#/g;
while (<>)
{
  s/\s/ (substr($headers, pos(), 1) eq '#')? '#' : ' ' /eg;
  @_ = split /\s*\#\s*/;
  # @_ now has true columns ready for whitespace trimming
}