Loop through days of month in bash

loop_month_days.sh

#!/bin/bash

# loop through days of month given the first day

startdate="2019-06-01"
enddate=$(date -d "$startdate + 1 month" +"%Y-%m-%d")

ndays=$(( ($(date -d "$enddate" +%s) - $(date -d "$startdate" +%s) )/(60*60*24) ))

for i in $(seq 0 $(($ndays - 1)) ); do
    date=$(date -d "$startdate + $i days" +"%Y-%m-%d")
    echo $date
done