$ cat car.csv
make,model,color,year
Honda,Civic,Red,2008
Toyota,Camry,Blue,2002
Honda,Accord,Red,1992
Nissan,Sentra,Blue,2009
Ford,Focus,Green,2009
Honda,Civic,Red,2003
Toyota,Corolla,Green,2002
Honda,Civic,Red,1992
Honda,Civic,Green,2008
Toyota,Camry,Orange,2002
Honda,Accord,Black,1992
Nissan,Sentra,White,2009
Ford,Focus,Green,2007

##</code><code>##

#!/usr/bin/perl -w
use strict;

#Run the script like, tail -n +2 car.csv | ./foo.pl
#I want to ignore the header

my $make; #Car Make
my $model; #Car Model
my $out_dir="/var/tmp/cars"; #Output directory for

while (<>) {
($make,$model) = split(/,/,$_,4);
 system("mkdir -p $out_dir/$make");
 open FILE, ">>$out_dir/$make/$model" or die $!;
   print FILE $_;
 close FILE;
}

##</code><code>##

$ cat /var/tmp/cars/Honda/Civic 
Honda,Civic,Red,2008
Honda,Civic,Red,2003
Honda,Civic,Red,1992
Honda,Civic,Green,2008

$ cat /var/tmp/cars/Honda/Accord 
Honda,Accord,Red,1992
Honda,Accord,Black,1992

$ cat /var/tmp/cars/Ford/Focus 
Ford,Focus,Green,2009
Ford,Focus,Green,2007