I'm guessing, but I think you asked about how a hash would be used, which makes me think that what you are asking for might be something like this:

open FILE, "data.txt" or die $!;          
while(<FILE>){
   chomp;                   

   my ($uniq,$one,$two,) = split ',';
                          # split the line into its fields

   $line_hash{$uniq} = qq($uniq $one $two);
                          # use a _unique_ key value
                          # describing the line to define
                          # a hash key, and splice the
                          # line to that key.
}
close FILE;                      
                          # now sort by the (presumed)
                          # numerical key, and print a test.

for( sort { $a <=> $b } keys %line_hash ){
    print "test: ",$line_hash{$_},$/ ;
}
[download]

The test will print out the first three comma-separated fields of each line, sorted by the key. Combine that, with what was posted by Hot Pastrami about creating and accessing anonymous arrays, or what lhoward posted about references to arrays, and I think you have a complete answer.

mkmcconn