#!/bin/sh
set -eu

usage() {
	cat <<-'EOF'
		Usage:
		  timestamp [-E]
	EOF
}

EXTENDED=false
while getopts 'E' flag; do
	case "$flag" in
		(E)
			EXTENDED=true
			;;
		(*)
			usage >&2
			exit 2
			;;
	esac
done
shift $((OPTIND - 1))


if [ "$EXTENDED" = true ]; then
	date '+%Y-%m-%dT%H:%M:%S%:z'
else
	date '+%Y-%m-%d'
fi