use strict;

my @files = <DATA>;
my %filehash = ();

#put the split data into a hash keyed by the filename
foreach (@files) {
        chomp;
    my @data = split /:/;
    $filehash{@data[2]} = [@data];
}

my ($key, $last, $temp, $infoline, @value);

#sort the hash by key
for $key (sort keys %filehash) {
    #determine the first letter of the key
    $temp = substr($key, 0, 1);

    #here's the control break...
    #if we haven't seen the first letter of the key before,
    #"break" control, do something special, and carry on...
    if ($last ne $temp) {
        $last = $temp;
        print "\n<H1>$last</H1>\n";
    }

    @value = @{$filehash{$key}};

    $infoline = qq(<a href="@value[0]/@value[2]"><img src="images/@val
+ue[3]" width="128" height="128" alt="@value[4]"></a><p>);
    print "\t$infoline\n";
}

__DATA__
/path:jpg:mfile.jpg:stuff:stuff
/path:jpg:afile.jpg:stuff:stuff
/path:jpg:anotherfile.jpg:stuff:stuff
/path:jpg:bfile:stuff.jpg:stuff
/path:jpg:cfile:stuff.jpg:stuff
/path:jpg:nfile:stuff.jpg:stuff
/path:jpg:dfile:stuff.jpg:stuff
/path:jpg:efile:stuff.jpg:stuff
/path:jpg:ffile:stuff.jpg:stuff
/path:jpg:gfile:stuff.jpg:stuff
/path:jpg:hfile:stuff.jpg:stuff
/path:jpg:ofile:stuff.jpg:stuff
/path:jpg:stillanotherfile.jpg:stuff:stuff
/path:jpg:ifile:stuff.jpg:stuff
/path:jpg:jfile:stuff.jpg:stuff
/path:jpg:kfile:stuff.jpg:stuff
/path:jpg:lfile:stuff.jpg:stuff
/path:jpg:pfile:stuff.jpg:stuff
/path:jpg:qfile:stuff.jpg:stuff
/path:jpg:rfile:stuff.jpg:stuff
/path:jpg:sfile:stuff.jpg:stuff
[download]

Cē