I would contend that you shouldn't even use a regex to solve this problem, since the problem pertains to decoding the data stored within a fixed-width columnar format.

For this, the appropriate tool is unpack:

#!/perl/bin/perl

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

my $str  = '06/19/2007  10:50 AM    <DIR>          1dfgfg';

my $spec = 'A12A12A15A10'; # adjust this spec to meet your columnar ne
+eds
my @arr  = unpack($spec, $str);

print Dumper(\@arr);
print "\n";

print "username is ", $arr[3], "\n";
print "\n";

__OUTPUT__
$VAR1 = [
          '06/19/2007',
          '10:50 AM',
          '<DIR>',
          '1dfgfg'
        ];

username is 1dfgfg
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