Docker image for conversion of time zones

Dockerfile

# USAGE
# docker build -t tzconv .
# docker run tzconv "2022-01-01 00:00:00 JST"
# 
# OPTIONAL: set alias to your shell configuration
# e.g. alias tzconv="docker run tzconv"
FROM ubuntu

RUN apt-get update && apt-get install tzdata

COPY tzconv.sh /tzconv.sh
RUN chmod +x /tzconv.sh

ENTRYPOINT ["/tzconv.sh"]

tzconv.sh

#!/bin/bash
TZS=(
	'UTC'
	'Asia/Tokyo'
	'America/Los_Angeles'
)
for tz in ${TZS[@]}; do
	if [ "$1" == "" ]; then
		TZ="${tz}" date "+%Y-%m-%d %H:%M:%S %Z"
	else
		TZ="${tz}" date "+%Y-%m-%d %H:%M:%S %Z" -d "$1"
	fi
done