See Date::Calc, for starters.

UPDATE:

I cooked up a solution that would work for my personal file naming convention.

Consider a directory full of files like: summary.interfaces.yyyymmdd
I could run the following code, and simply grep this directory for all files ending in "$period".

#!/usr/local/bin/perl -w

use strict;

#Usage: $0 <yyyy> <1 2 3> #period 1,2,3, that is

die "Usage: $0 <yyyy> <1 2 3>, #period 1,2,3, that is\n" unless @ARGV 
+==2;
my $prepend = $ARGV[0];
my $per = $ARGV[1];
my @period;
my @files;


if ($per eq 1) {
@period = ("$prepend"."0101", "$prepend"."0630");
}
elsif ($per eq 2) {
@period = ("$prepend"."0701", "$prepend"."0831");
}
elsif ($per eq 3) {
@period = ("$prepend"."0901", "$prepend"."1231");
}
else {die "Usage: $0 <yyyy> <1 2 3>, #period 1,2,3, that is\n";}

foreach my $element(@period) {
print "$element\n";
}
my $from = $period[0];
my $to = $period[1];

 while ( $from < $to ) {
    print "$from\n";
} continue {
$from++;
}
[download]

Certainly not the prettiest, but it would work for me.

HTH,

Steve

update again:corrected typo