use IO::File ();

##  local $/;  # you're not using this

my $fh = IO::File->new();  # declare this just once

foreach $file (sort keys %altnames) { 
   my ($hr_title) = ( $file =~ m/(.*)\.txt/ );
   print "<hr> <h1 align=center> $hr_title </h1>\n";
                # don't need parens for print ...

   $fh->open( "$dir/$file" ) or die $!; # you gotta check!
   while (<$fh>) {
      print;
   }
   $fh->close;
}