#!/usr/bin/perl
use strict;
use warnings;

my $file = $ARGV[0] || 'export.dat';
open(my $fh, '<', $file) or die "Unable to open '$file' for reading: $!";
my @buffer;
while (<$fh>) {
    if (/^1(\d+.*)/) {                    # Start of new record
        output_data(@buffer) if @buffer;  # process last record if not first
        @buffer = $1;                     # put new line in buffer
    }
    else {
        push @buffer, $_;                 # Add line to buffer
    }
}
output_data(@buffer) if @buffer;          # Process last record if present

sub output_data {}