#!/usr/bin/env perl
use strict;
use diagnostics;

open my $read_log, '<', '/home/jayu_rao/test_output/app.log' or die $!;
open my $write_tmp_app_log, '>', '/home/jayu_rao/test_output/write_tmp_app.log' or die $!;

my @patterns = (
  qr/.*Error.*/,
  qr/.*error.*/,
  qr/.*ERROR.*/,
  qr/.*FATAL.*/,
  qr/.*Critical.*/,
  qr/.*exception.*/,
);

my @lines=<$read_log>;
my $i;

for (@patterns){

for $i (0..$#lines) {
  next unless $lines[$i] =~ $_;
  my $a = $i - 5 < 0 ? 0 : $i - 5;;
  my $b = $i + 5 > $#lines ? $#lines : $i + 5;
  for $i($a..$b){
  print $write_tmp_app_log $lines[$i]
  };
 }
}
close $read_log;
close $write_tmp_app_log;