How to generate consecutive week range dates for n past weeks

Question

I would like to generate a list of n week range dates going backward from the current week, like so

2014-03-22 2014-03-28
2014-03-15 2014-03-21
2014-03-08 2014-03-14
etc.

where the first date in each row is the beginning of the weekly period, which starts Saturday and ends Friday.

My preference would be to do this in a shell script, using awk or other Unix tools. The field delimiter doesn't matter, but the records should be one per line.

Answer 1

n=5    
for i in $(seq 0 $((n-1))); do
    echo "$(date -d "last saturday -$i weeks" +"%Y-%m-%d") $(date -d "friday -$i weeks" +"%Y-%m-%d")"; 
done

Output:

2014-03-22 2014-03-28
2014-03-15 2014-03-21
2014-03-08 2014-03-14
2014-03-01 2014-03-07
2014-02-22 2014-02-28

Answer 2

If GNU date is a problem, how about Perl? This should use only standard modules, for a recent-ish version of Perl

use v5.10;
use Time::Piece;
use Time::Seconds;

$, = " ";

# get the previous saturday, unless today is saturday
my $day = localtime;
$day -= $day->wday * ONE_DAY unless $day->wday == 6;

while (1) {
    say $day->strftime("%F"), ($day + 6*ONE_DAY)->strftime("%F"); 
    $day -= 7 * ONE_DAY;
}