I'm not sure what you are trying to achieve, but if the following (leaving out the HTML stuff for the moment) does what you want let us know:

use strict;
use warnings;

my @lines;

while (<DATA>) {
  my ($first, $sort, $second, $tail) = m/^(\w+)\s+(\d+)\s+(\w+)(.*)$/;
  die "Unable to match any lines:$!\n" if ! defined $tail;
  push @lines, [$sort, $first, $second, $tail];
}

print join "\n", map {"$_->[1] $_->[0] $_->[2]$_->[3]"} sort {$a->[0] 
+<=> $b->[0]} @lines;

__DATA__
a 0 f g j k
b 4 y h t e e e
c 1 n s v c x
d 3 f f f
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Prints:

a 0 f g j k
c 1 n s v c x
d 3 f f f
b 4 y h t e e e
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use Sort::Key qw(ikeysort);

my $buffer;

open (INPF,"<input.dat") or die "Can't open input.dat: $!\n";
for (ikeysort {/^\w+\s+(\d+)/; $1} <INPF>) {
  m/^(\w+)\s+(\d+)\s+(\w+)(.*)$/ or die "Unable to match any lines:$!\
+n";
  if ($2 < 90) { $buffer .= "<tr bgcolor='#00FF00'><td>$1</td><td>$2</
+td><td>$3</td><td>$4</td></tr>\n";
  } elsif ($2 < 180) {
    $buffer .= "<tr bgcolor='#FF6600'><td>$1</td><td>$2</td><td>$3</td
+><td>$4</td></tr>\n";
  } else {
    $buffer .= "<tr bgcolor='#FF0000'><td>$1</td><td>$2</td><td>$3</td
+><td>$4</td></tr>\n";
  }
}
close INPF;
[download]

This is good stuff. However, having downloaded your CPAN module. Note that I changed the code above so it does a descending sort e.g.


for (rikeysort {/^\w+\s+(\d+)/; $2} <INPF>) {
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This error now occurs


Can't call method "rikeysort" on an undefined value at ./x.pl line 401
+, <INPF> line 12.
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There are only 12 records in my test input file
It works fine if I use ascending key sort
Any ideas what is happenning here ?

have you changed the use Sort::Key statement to import rikeysort instead of ikeysort?

use Sort::Key qw(rikeysort);
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my ($first, $sort, $second, $tail) = split(/\s+/, $_);
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m/^(\w+)\s+(\d+)\s+(\w+)(.*)$/
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NB: I used split(/\s+/, $_) and not split(' ', $_) because you were matching /^(\w+), which may just have been for efficiency and anchoring, but I don't know that you didn't need to make sure that there was no leading white space on the line in the input file.

I have not used GrandFather's map because I needed to do quite a lot to the elements returned by the sort (the tests on $sort and the sprintf) and it looked like it was going to be messy and possibly difficult trying to fit it all in there.

I like map, but I tend to shy away from using it for more than the most basic usage - I know 95%+ of the people I've ever worked with who have to deal with Perl would not be able to understand how the map worked, but could all unroll a foreach loop if they needed to change the code after I had moved on to my next contract.

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";
[download]

I like map...

calling die from inside a map block is not a very good idea, it can hit a bug on the perl interpreter that has only recently being corrected:

for (1) { map { die } 2 }
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Good point re the die statement. It's just habit to put that line in. I've changed it accordingly. Thanks.