Shell Programming and Scripting

#!/usr/bin/perl
open (DR,"DR.txt");
open (DC,"DC.txt");
open (DL,"DL.txt");
open (F,"formation.txt");
while (<F>) {
  chomp;
  if ($_ eq "DR") {
    chomp ($line = <DR>);
  }
  elsif ($_ eq "DC") {
    chomp ($line = <DC>);
  }
  elsif ($_ eq "DL") {
    chomp ($line = <DL>);
  }
  else {print "error\n"; next}
  printf "%s %s\n",$_,$line;
}
close F;
close DR;
close DC;
close DL;