my ($first, $sort, $second, $tail) = split(/\s+/, $_);

##</code><code>##

m/^(\w+)\s+(\d+)\s+(\w+)(.*)$/

##</code><code>##

use strict;
use warnings;

my $buffer;

my $input = "input.dat";

my %colour = (

   'lt_90'  => '#00FF00',
   'lt_180' => '#FF6600',
   'gt_179' => '#FF0000'

);

my @lines;

open( INPF, $input ) or die "Can't read '$input': $!\n";
while (<INPF>) {

    my ($first, $sort, $second, $tail) = split(/\s+/, $_);

    if ( defined $tail && $sort =~ /^\d+$/ ) {

        push(@lines, [$first, $sort, $second, $tail]);

    } else {

        # die "Unable to match any lines: $!\n";

        # Do you really want to die with $! here?
        # There wasn't an error, just a failed test,
        # so $! won't have a relevant message in it.
        # (I get "Bad file descriptor" YMMV on your OS?)
        # Perhaps you want something like:

        chomp();
        die "line: '$_' does not match input format\n";

    }

}
close (INPF);

for my $line ( sort { $a->[1] <=> $b->[1] } @lines ) {

    my ($first, $sort, $second, $tail) = @{$line};

    my $colour = "gt_179";

    if ( $sort < 90 ) {

        $colour = "lt_90";

    }
    elsif ( $sort < 180 ) {

        $colour = "lt_180";

    }

    $buffer .= sprintf (
        "<tr bgcolor='%s'><td>%s</td><td>%s</td><td>%s</td><td>%s</td></tr>\n",
        $colour{$colour}, $first, $sort, $second, $tail);

}

print "$buffer";