#!/bin/bash
if [[ $# -lt 3 ]]; then
    echo "Usage: getdt <from> <to> (format)"
    return -1
fi
from_date=$1
to_date=$2
format="%02d days, %02d:%02d:%02d"
if [[ $# -gt 3 ]]; then
    format=$3
fi
target_epoch=$(date -d "$from_date" +%s)
now_epoch=$(date -d "$to_date" +%s)
remaining_seconds=$((target_epoch - now_epoch))

days=$((remaining_seconds / 86400))
hours=$(((remaining_seconds % 86400) / 3600))
minutes=$(((remaining_seconds % 3600) / 60))
seconds=$((remaining_seconds % 60))

printf "%02d days, %02d:%02d:%02d" $days $hours $minutes $seconds