Loop over dates in a Bash script

loop_dates.sh

#!/bin/bash

#=======================================================================
# Specify the "start" and "end" time.
#=======================================================================
# Use format "HH:MM YYYY-MM-DD"
start="00:00 2021-04-01"
end="00:00 2021-04-02"
increment="+1 hours"
#=======================================================================

# Convert start and end time to full Bash datetime format
# For example, it converts "00:00 2021-04-01" to "Thu Apr 1 00:00:00 GMT 2021"
start=$(date -d "${start}")
end=$(date -d "${end}")

# The below while statement will loop over each date between the start and
# end time. Each loop will increment the date by "+1 hours" (defined above).

# NOTE: The +%s in the first line converts the date to "seconds since 
# EPOC" which makes the comparison between start and end time possible.
# See bottom of page here: https://phoenixnap.com/kb/linux-date-command
while (( $(date -d "${start}" +%s) <= $(date -d "${end}" +%s) )); do
    echo      #< empty echo statement prints a blank line
    echo Current Loop Date: ${start}
   
    # DO SOME STUFF WITH THE DATE
   
    # Increment the value. This changes the value of `$start` every loop
    # with the next date.
    start=$(date -d "${start} ${increment}")
done