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

sub addheader{

my($infile,$header)=@_;
my $text = do { local( @ARGV, $/ ) = $infile ; <> } ;
open(FILE,">$infile");
print FILE $header;
print FILE $text;
close FILE;
}

my $migfile = "SUBSCRPT_DATA_20121029_11001.DAT";

my $header= "44,,,2\n";

&addheader($migfile,$header);