Syslog manual rotatation. It fills alphabet as temprary year information.

syslog-manual-rotate.pl

#!/usr/bin/perl

use strict;
use warnings;

use Term::ANSIColor qw(colored);

my %mon_digit_of = (
    qw(Jan 1 Feb 2 Mar 3 Apr 4 May 5 Jun 6 Jul 7 Aug 8 Sep 9 Oct 10 Nov 11 Dec 12)
);

my $cur_mon = '';
my $cur_year_alphabet = "a";
my $cur_fh;

my $file = shift
    or die "usage: $0 FILE";

open my $fh, '<', $file or die;
while (<$fh>) {
    my ($mon) = /^(\w\w\w)/;
    if ( $cur_mon ne $mon ) {
        info("change month: $mon");
        my $is_skew = is_skew($cur_mon, $mon);
        if ( is_skew($cur_mon, $mon) ) {
            $cur_year_alphabet++;
            info("change year: $cur_year_alphabet");
        }
        $cur_fh = get_cur_fh($mon_digit_of{$mon}, $cur_year_alphabet);
        $cur_mon = $mon;
    }
    info("line tick: $.") if $. % 1_000_000 == 0;
    print {$cur_fh} $_;
}
close $fh;

sub is_skew {
    my ($mon1, $mon2) = map { $mon_digit_of{$_} || 0 } @_;
    #print "> mon1,mon2 = $mon1,$mon2\n";
    if ( $mon1 > $mon2 ) {
        return 1; # skew
    } else {
        return 0;
    }
}

sub get_cur_fh {
    my ($mon_digit, $year_alphabet) = @_;
    open my $fh, '>', "$file.$year_alphabet-$mon_digit";
    return $fh;
}

sub info {
    my $message = shift;
    print colored($message, "green"), "\n";
}