You should be able to get your desired result with Non capturing groupings: 
use strict;
use warnings;

my $result = <<'EOT';
transaction 1234567; promote; 2014/08/01 10:22:37 ; user: john
  # Performing a "promote" on file.
  /./abc/desf/test.pl 138699/1 (138700/1) 

transaction 4578643; promote; 2014/08/01 10:22:37 ; user: sam
  /./abc/desf/test.pl 138699/1 (138700/1) 
EOT

while ($result =~ /transaction (\d+).*user:\s*(\S+)\s*(?:#\s*(.*))?/g)
+ {
            my ($transaction, $user, $comment) = ($1, $2, $3);
            printf "%-12s %-10s %s\n", $1, $2, $3//'';
}

[download]

Note the // (Logical Defined Or) to avoid an undef warning in your print.

#11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.

In reply to Re: Reg the split expression by kennethk
in thread Reg the split expression by sravs448

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