Central European Timezone snippet for times when you have no control over /etc/TZ or /etc/timezone

gistfile1.bash

cetz() {
	LANG=C
	# current year
	YEAR=`date +%Y`
	# current time stamp
	NOW=`date +%s`

	# transition day for Central European Summer Time
	LAST_SUNDAY_OF_MARCH=`cal 3 $YEAR | sed '/^$/d' | tail -n 1 | cut -d ' ' -f 1`
	# transition day for Central European Time
	LAST_SUNDAY_OF_OCTOBER=`cal 10 $YEAR | sed '/^$/d' | tail -n 1 | cut -d ' ' -f 1`

	# time stamp of summer time transition
	CEST_TRANSITION=`date -d "${YEAR}-03-$LAST_SUNDAY_OF_MARCH 01:00:00 UTC" +%s`
	## for *BSD
	##CEST_TRANSITION=`date -ju ${YEAR}03${LAST_SUNDAY_OF_MARCH}0100.00 +%s`
	# time stamp of winter time transition
	CET_TRANSITION=`date -d "${YEAR}-10-$LAST_SUNDAY_OF_OCTOBER 01:00:00 UTC" +%s`
	## for *BSD
	##CET_TRANSITION=`date -ju ${YEAR}10${LAST_SUNDAY_OF_OCTOBER}0100.00 +%s`

	if [ $NOW -lt $CEST_TRANSITION ] || [ $NOW -ge $CET_TRANSITION ]; then
		# winter time
		echo CET-1 | tee $HOME/.tz
	else
		# summer time
		echo CEST-2 | tee $HOME/.tz
	fi
}

##example usage in ~/.profile:
##TZ=`cetz`; export TZ