#!/bin/bash

uname -a

echo "*** date in a loop"

base=$(date +"%s")
for((i=0; i<5; ++i)); do
    date -d @$((i * 24 * 60 * 60 + base)) +%Y-%m-%d
done

echo "*** perl"

perl -le 'use POSIX qw(strftime);
    $t = time;
    for $_ (1..5) {
        print strftime("%Y-%m-%d", localtime($t));
        $t += 24 * 60 * 60 }'