#!/usr/bin/perl -w
#########################################################
 
use strict;
use Tie::File;
 
my @fin=();
my @fout=();
 
tie @fin,"Tie::File","bigfile.txt" or die $!;
my $fcount=1;
for(my $ix=0;$ix<=$#fin;$ix+=30){
    my $end = ( $ix+29 <=$#fin ? $ix+29 : $#fin );
    my $outfilename = sprintf("litte_file_%0.2d.txt",$fcount);
    tie @fout,"Tie::File",$outfilename or die $!;
    for(my $iy=$ix;$iy<=$end;$iy++){
        push @fout,$fin[$iy];
    }
    untie @fout;
    $fcount++;
}