Could not resist, here is a column index driven approach. 

use strict;
use warnings;
use Data::Dumper;

my $data1 = <<EO1;
38375U|36182D|36182D1|HMAG|HMBSWEE|20150416|mortgage
383333|361333|3618333|HABS|HABSDDE|20150330|mortgage2
EO1

my $data2 = <<EO2;
38375U|3DD82D|36FF333|HMAG|HMBSWEE|9010|765423|364633|46566
38EE33|361DD3|36LLE33|H99S|HAOOODE|2330|377233|347433|34488
EO2

sub process_file {
  my ( $file, $keys, $in, $out, $hash ) = @_;
  open my $fh, "<", $file;
  while(<$fh>) {
    chomp;
    my @attr = split /[|]/;
    @{ $hash->{join '|', @attr[@$keys]} }[ @$out ] = @attr[ @$in ];
  }
  close $fh;
}

my %result;
process_file( \$data1, [0,3,4], [0..6], [0..6], \%result );
process_file( \$data2, [0,3,4], [0,3,4,5..8], [0,3,4,7..10], \%result 
+);

print Dumper \%result;

[download]

Dealing with ignoring the header line and printing is left as an exercise...

In reply to Re: Outer Join on 2 files by hdb
in thread Outer Join on 2 files by healingtao

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