How to create a date generator in shell? - shell

Question

I want to pull some information from a website from past 4 years and each file is date based, like http://ransompull.com/pullme/2013-04-06/example.2013-04-06.txt
and it is the starting file and it ends today, so i want to pull all the txt files from last 4 years.
What I tried:
DATE=`date +%Y`
MONTH='01'
DAY='1'
for i in range(1,31);
for j in range(01,12):
do wget http://ransompull.com/pullme/$DATE$i/example.$DATE$i.txt;
done
done
But this seems to wrong as iterating over month and date is not feasible as it is not giving desired output.Any suggestions on how to pull all data from
http://ransompull.com/pullme/2013-04-06/example.2013-04-06.txt
to
http://ransompull.com/pullme/2017-08-10/example.2017-08-10.txt

Answer 1

Instead of counting years, months and days,
you could just count days relative to the start date.
If you have the GNU implementation of the date command,
you can use it to compute the relative date, for example:
date +%F -d '2013-04-06 + 1000 days'
This outputs 2016-01-01.
You can create a loop, generating dates by incrementing the number of days from start, until you reach the end:
start=2013-04-06
end=2017-08-10
date=$start
days=0
while [ "$date" != "$end" ]; do
date=$(date +%F -d "$start + $days days")
wget http://ransompull.com/pullme/$date/example.$date.txt
((days++))
done

Answer 2

try this:
$startdate=get-date 2017-08-11
$enddate=$startdate.AddYears(-4)
0..($startdate - $enddate).Days | %{wget ("http://ransompull.com/pullme/{0:yyyy-MM-dd}/example.{0:yyyy-MM-dd}.txt" -f $startdate.AddDays(-$_))}