split access_log by months

#!/usr/bin/perl

my $in = @ARGV[0];
open (IN, $in);

my $f = '';

while (my $str = )
{
    $str =~ m#\[(\d{2})/(\w{3})/(\d{4}):.*]#;
    #print "$3$2 $str \n";
    my $cur = "$3$2";
    if ( $cur ne $f)
    {
        if ($f ne '') {close OUT;}

        $f = $cur;
        open (OUT, "> $f-$in");
        print "$f-$in\n";
    }

    print OUT $str;
}


close IN;
close OUT;
#return 0;
exit 0;

#in: parse.pl access_log
#out: 2011Feb-access_log, ...