2015-02-27 16:35:29,832 [[48:1JK5DE9A]] INFO - performing task
2015-02-27 16:39:31,850 [[50:1EB1DB9F]] INFO - text: [[abcd.this is not needed]] mystring
2015-02-27 16:45:24,250 [[49:3CE1DB9A]] INFO - text: [[efghijk.this portion is also not needed]] mystring
2015-02-27 16:55:29,832 [[48:1JK5DE9A]] INFO - task done.
2015-02-27 16:55:31,850 [[50:1EB1DB9F]] INFO - text: [[lmn. again not needed]] mystring
2015-02-27 16:57:13,435 [[50:1EB1DB9F]] INFO - text: [[lmn. repetition. Again not needed]] mystring

##</code><code>##

perl log.pl
Can't use an undefined value as a symbol reference at log.pl line 30, <$_[...]>
        line 532 (#1)
    (F) A value used as either a hard reference or a symbolic reference must
    be a defined value.  This helps to delurk some insidious errors.

Uncaught exception from user code:
        Can't use an undefined value as a symbol reference at log.pl line 30, <$_[...]> line 532.
 at log.pl line 30

##</code><code>##

#!/usr/bin/perl -w

use strict;
use warnings;
use autodie;
use diagnostics;

open my $read_log, '<', '/home/jay/test_output/tmp_app.log' or die $!;

my $pattern = 'mystring';
my @log_lines=<$read_log>;
my @all_lines_occurrences;
my @all_extracts;
my @unique_values;

   for(@log_lines){

        if ($_ =~ m/.*$pattern.*/) {
                push (@all_lines_occurrences, $_);
                #print $_ "\n";
        }
   }

for (@all_lines_occurrences) {
/^\d+\-\d+\-\d+ \d+:\d+:\d+\,\d+ \[(.*)\] .* \[(.*)\.(.*)\] .*\\n/;
      push (@all_extracts, $2);
#print "target type: $2 \n";
}

for(@all_extracts){
        print $_ "\n";
}

my @unique_values = do { my %seen; grep { !$seen{$_}++ } @all_extracts };

print "\n Unique values are:\n";
for (@unique_values) {
print $_ "\n";
}
close $read_log;