a shortcut program to convert timezone

tz.sh

#!/bin/bash
# Usage: tz.sh from-timezone to-timezone time
# Example: tz.sh America/Los_Angeles America/New_York '2000-01-01 00:01:02'

from=$1
to=$2
if [[ "$3" == "" ]]; then
  time=`date -R`
else
  time=$3
fi
TZ="$from" date -R --date "$time" | TZ="$to" xargs -I {} date -R --date {}