Simple program to count the type of log events in a Log4Perl file

count_log

#!/usr/bin/perl

use strict;
use warnings;

my $logs;

while (<>) {
  my ($date, $time, $type) = split;

  # Some event logs have newlines in them, so we try
  # to skip lines that don't parse correctly
  next unless defined $type and defined $time;

  # Grab the time and cut into ten-minute chunks
  $time = substr($time, 0, 4) . '0';

  # We'll still have some lines that don't look right
  next unless $time =~ /^\d\d:\d\d$/;

  $logs->{$time}{$type}++;
}

for my $min (sort keys %$logs) {
  print $min;
  for my $type (qw[INFO DEBUG WARN ERROR FATAL]) {
    print " : $type [", ($logs->{$min}{$type} // 0), "]";
  }
  print "\n";
}