#!/bin/sh
# DATE From To

while getopts cfF:t:T: opt; do
	case $opt in
		c) tz_from="Asia/Shanghai";;
		f) tz_from="$(tzselect)";;
		F) tz_from="$OPTARG";;
		t)	for i in $(seq "$OPTARG"); do
				tz_to="$tz_to,$(tzselect)"
			done;;
		T) tz_to="$OPTARG";;
		\?) exit 1;;
	esac
done
shift $((OPTIND-1))

time_from="TZ=\"${tz_from:-$(readlink /etc/localtime | sed 's#.*/\(.*/.*\)$#\1#')}\" ${1:-now}"

date -d "$time_from"
TZ="Asia/Shanghai" date -d "$time_from"
date -d "$time_from" -u 
date -d "$time_from" +%s
if [ "$tz_from" ] && [ "$tz_from" != "Asia/Shanghai" ]; then
	TZ="$tz_from" date -d "$time_from"
fi
IFS=',' 
for tz in $tz_to; do
	TZ="$tz" date -d "$time_from"
done