use strict;
use warnings;

use POSIX qw{ strftime };
use Digest::MD5;

my $origFile = q{cr835.txt};
open my $origFH, q{<}, $origFile
   or die qq{open: < $origFile: $!\n};
my $line = <$origFH>;
close $origFH or die qq{close: < $origFile: $!\n};

my $payeeID;
if ( $line =~ m{INC\*XX\*(\d+)} )
{
    $payeeID = $1;
}
else
{
    die qq{Could not match payee ID\n};
}

my $newFile
   = qq{cr835-}
   . $payeeID
   . strftime q{-processed_%Y-%m-%d_%H-%M.txt}, localtime;

open my $newFH, q{>}, $newFile
   or die qq{open: > $newFile: $!\n};
print $newFH $line;
close $newFH or die qq{close: > $newFile: $!\n};

my $origMD5 = Digest::MD5
   ->new()
   ->addfile( do { open my $fh, q{<}, $origFile or die $!; $fh; } )
   ->hexdigest();
my $newMD5  = Digest::MD5
   ->new()
   ->addfile( do { open my $fh, q{<}, $newFile or die $!; $fh; } )
   ->hexdigest();

if ( $origMD5 eq $newMD5 )
{
    unlink $origFile or die qq{unlink: $origFile: $!\n};
}
else
{
    die qq{Original and new files differ\n};
}