Hi,
Try this.... it is quite helpful to you.
here is the code....

   open( ABB, '<', 'jabb.txt' ) or die "Couldn't open ABB.\n$!";
   open( IN, '<', 'input.txt' ) or die "Couldn't open infile.\n$!";
   open( OUT, '>', 'output.out' ) or die "Couldn't open outfile.\n$!";

   my @myin = <IN>;

   while(<ABB>)
   {
        ($abb,$full) = split/\t/,$_;
        chomp($abb);
        chomp($full);
        for ($t=0;$t<=$#myin;$t++)
        {
          $myin[$t] =~s/$full/$abb/g;
        }
   }
    print OUT "@myin\n";

Regards Franklin