#!/usr/bin/env perl

use strict;
use warnings;
use autodie;

my $filename_prefix = 'pm_1155986_out_';
my $filename_suffix = '.txt';
my $filename_number = 0; 
my $out_fh;
my ($start_re, $end_re) = (qr{TRANSACTION STARTED}, qr{TRANSACTION END});

open my $in_fh, '<', 'pm_1155986_in.txt';

while (<$in_fh>) {
    if (/$start_re/ .. /$end_re/) {
        if (/$start_re/) {
            open $out_fh, '>',
                $filename_prefix . $filename_number++ . $filename_suffix;
            next;
        }

        if (/$end_re/) {
            close $out_fh;
            next;
        }

        print $out_fh $_;
    }
}