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

Question

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.

Answer 1

Rather than performing hazardous and non locale-agnostic date arithmetic, using a unix timestamp ensures consistent results

Using Bash grammar:

#!/usr/bin/env bash

start_date=2023-11-04
end_date=2023-11-06

start_ts=$(date -d "$start_date" +%s)
end_ts=$(date -d "$end_date" +%s)

for ((ts=start_ts; ts<=end_ts; ts+=3600))
do printf '%(%Y-%m-%d-%H)T\n' "$ts"
done

Using POSIX-shell grammar:

#!/usr/bin/env sh

start_date=2023-11-04
end_date=2023-11-06

start_ts=$(date -d "$start_date" +%s)
end_ts=$(date -d "$end_date" +%s)

ts=$start_ts
while [ "$ts" -le "$end_ts" ]
do
  date -d "@$ts" +'%Y-%m-%d-%H' 
  ts=$((ts + 3600))
done