Generate all dates between two dates in %Y-%m-%d-%H format in bash

November 6, 2023

Using bash I want to generate all dates between, say, 2023-11-04-00 and 2023-11-06-00 where the format is %Y-%m-%d-%H. I have tried :

#!/bin/bash

d=2023-11-04
while [ "$d" != 2023-11-06 ]; do
        d=$(date -d "$d 1 hour")
        u=$(date -d "$d" +'%Y-%m-%d-%H')
        echo $u
done

It works but I get an infinite loop and can’t quite figure out what is happening.

>Solution :

Let’s have a look at what $d actually looks like:

$ d=2023-11-04
$ d=$(date -d "$d 1 hour")
$ echo "$d"
Sat Nov  4 01:00:00 AM EDT 2023

Oh. That’s not a string that’s ever going to be equal to 2023-11-06.

Let’s see if we can fix that:

#!/bin/bash

d=2023-11-04
while [ "$(date -d "$d" +'%Y-%m-%d')" '<' 2023-11-06 ]; do
        d=$(date -d "$d 1 hour")
        u=$(date -d "$d" +'%Y-%m-%d-%H')
        echo $u
done

Much better.