michael@0: #! /bin/ksh
michael@0: 
michael@0: # '@(#)tzselect.ksh	8.1'
michael@0: 
michael@0: # Ask the user about the time zone, and output the resulting TZ value to stdout.
michael@0: # Interact with the user via stderr and stdin.
michael@0: 
michael@0: # Contributed by Paul Eggert.
michael@0: 
michael@0: # Porting notes:
michael@0: #
michael@0: # This script requires several features of the Korn shell.
michael@0: # If your host lacks the Korn shell,
michael@0: # you can use either of the following free programs instead:
michael@0: #
michael@0: #	<a href=ftp://ftp.gnu.org/pub/gnu/>
michael@0: #	Bourne-Again shell (bash)
michael@0: #	</a>
michael@0: #
michael@0: #	<a href=ftp://ftp.cs.mun.ca/pub/pdksh/pdksh.tar.gz>
michael@0: #	Public domain ksh
michael@0: #	</a>
michael@0: #
michael@0: # This script also uses several features of modern awk programs.
michael@0: # If your host lacks awk, or has an old awk that does not conform to Posix.2,
michael@0: # you can use either of the following free programs instead:
michael@0: #
michael@0: #	<a href=ftp://ftp.gnu.org/pub/gnu/>
michael@0: #	GNU awk (gawk)
michael@0: #	</a>
michael@0: #
michael@0: #	<a href=ftp://ftp.whidbey.net/pub/brennan/>
michael@0: #	mawk
michael@0: #	</a>
michael@0: 
michael@0: 
michael@0: # Specify default values for environment variables if they are unset.
michael@0: : ${AWK=awk}
michael@0: : ${TZDIR=$(pwd)}
michael@0: 
michael@0: # Check for awk Posix compliance.
michael@0: ($AWK -v x=y 'BEGIN { exit 123 }') </dev/null >/dev/null 2>&1
michael@0: [ $? = 123 ] || {
michael@0: 	echo >&2 "$0: Sorry, your \`$AWK' program is not Posix compatible."
michael@0: 	exit 1
michael@0: }
michael@0: 
michael@0: # Make sure the tables are readable.
michael@0: TZ_COUNTRY_TABLE=$TZDIR/iso3166.tab
michael@0: TZ_ZONE_TABLE=$TZDIR/zone.tab
michael@0: for f in $TZ_COUNTRY_TABLE $TZ_ZONE_TABLE
michael@0: do
michael@0: 	<$f || {
michael@0: 		echo >&2 "$0: time zone files are not set up correctly"
michael@0: 		exit 1
michael@0: 	}
michael@0: done
michael@0: 
michael@0: newline='
michael@0: '
michael@0: IFS=$newline
michael@0: 
michael@0: 
michael@0: # Work around a bug in bash 1.14.7 and earlier, where $PS3 is sent to stdout.
michael@0: case $(echo 1 | (select x in x; do break; done) 2>/dev/null) in
michael@0: ?*) PS3=
michael@0: esac
michael@0: 
michael@0: 
michael@0: # Begin the main loop.  We come back here if the user wants to retry.
michael@0: while
michael@0: 
michael@0: 	echo >&2 'Please identify a location' \
michael@0: 		'so that time zone rules can be set correctly.'
michael@0: 
michael@0: 	continent=
michael@0: 	country=
michael@0: 	region=
michael@0: 
michael@0: 
michael@0: 	# Ask the user for continent or ocean.
michael@0: 
michael@0: 	echo >&2 'Please select a continent or ocean.'
michael@0: 
michael@0: 	select continent in \
michael@0: 	    Africa \
michael@0: 	    Americas \
michael@0: 	    Antarctica \
michael@0: 	    'Arctic Ocean' \
michael@0: 	    Asia \
michael@0: 	    'Atlantic Ocean' \
michael@0: 	    Australia \
michael@0: 	    Europe \
michael@0: 	    'Indian Ocean' \
michael@0: 	    'Pacific Ocean' \
michael@0: 	    'none - I want to specify the time zone using the Posix TZ format.'
michael@0: 	do
michael@0: 	    case $continent in
michael@0: 	    '')
michael@0: 		echo >&2 'Please enter a number in range.';;
michael@0: 	    ?*)
michael@0: 		case $continent in
michael@0: 		Americas) continent=America;;
michael@0: 		*' '*) continent=$(expr "$continent" : '\([^ ]*\)')
michael@0: 		esac
michael@0: 		break
michael@0: 	    esac
michael@0: 	done
michael@0: 	case $continent in
michael@0: 	'')
michael@0: 		exit 1;;
michael@0: 	none)
michael@0: 		# Ask the user for a Posix TZ string.  Check that it conforms.
michael@0: 		while
michael@0: 			echo >&2 'Please enter the desired value' \
michael@0: 				'of the TZ environment variable.'
michael@0: 			echo >&2 'For example, GST-10 is a zone named GST' \
michael@0: 				'that is 10 hours ahead (east) of UTC.'
michael@0: 			read TZ
michael@0: 			$AWK -v TZ="$TZ" 'BEGIN {
michael@0: 				tzname = "[^-+,0-9][^-+,0-9][^-+,0-9]+"
michael@0: 				time = "[0-2]?[0-9](:[0-5][0-9](:[0-5][0-9])?)?"
michael@0: 				offset = "[-+]?" time
michael@0: 				date = "(J?[0-9]+|M[0-9]+\.[0-9]+\.[0-9]+)"
michael@0: 				datetime = "," date "(/" time ")?"
michael@0: 				tzpattern = "^(:.*|" tzname offset "(" tzname \
michael@0: 				  "(" offset ")?(" datetime datetime ")?)?)$"
michael@0: 				if (TZ ~ tzpattern) exit 1
michael@0: 				exit 0
michael@0: 			}'
michael@0: 		do
michael@0: 			echo >&2 "\`$TZ' is not a conforming" \
michael@0: 				'Posix time zone string.'
michael@0: 		done
michael@0: 		TZ_for_date=$TZ;;
michael@0: 	*)
michael@0: 		# Get list of names of countries in the continent or ocean.
michael@0: 		countries=$($AWK -F'\t' \
michael@0: 			-v continent="$continent" \
michael@0: 			-v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
michael@0: 		'
michael@0: 			/^#/ { next }
michael@0: 			$3 ~ ("^" continent "/") {
michael@0: 				if (!cc_seen[$1]++) cc_list[++ccs] = $1
michael@0: 			}
michael@0: 			END {
michael@0: 				while (getline <TZ_COUNTRY_TABLE) {
michael@0: 					if ($0 !~ /^#/) cc_name[$1] = $2
michael@0: 				}
michael@0: 				for (i = 1; i <= ccs; i++) {
michael@0: 					country = cc_list[i]
michael@0: 					if (cc_name[country]) {
michael@0: 					  country = cc_name[country]
michael@0: 					}
michael@0: 					print country
michael@0: 				}
michael@0: 			}
michael@0: 		' <$TZ_ZONE_TABLE | sort -f)
michael@0: 
michael@0: 
michael@0: 		# If there's more than one country, ask the user which one.
michael@0: 		case $countries in
michael@0: 		*"$newline"*)
michael@0: 			echo >&2 'Please select a country.'
michael@0: 			select country in $countries
michael@0: 			do
michael@0: 			    case $country in
michael@0: 			    '') echo >&2 'Please enter a number in range.';;
michael@0: 			    ?*) break
michael@0: 			    esac
michael@0: 			done
michael@0: 
michael@0: 			case $country in
michael@0: 			'') exit 1
michael@0: 			esac;;
michael@0: 		*)
michael@0: 			country=$countries
michael@0: 		esac
michael@0: 
michael@0: 
michael@0: 		# Get list of names of time zone rule regions in the country.
michael@0: 		regions=$($AWK -F'\t' \
michael@0: 			-v country="$country" \
michael@0: 			-v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
michael@0: 		'
michael@0: 			BEGIN {
michael@0: 				cc = country
michael@0: 				while (getline <TZ_COUNTRY_TABLE) {
michael@0: 					if ($0 !~ /^#/  &&  country == $2) {
michael@0: 						cc = $1
michael@0: 						break
michael@0: 					}
michael@0: 				}
michael@0: 			}
michael@0: 			$1 == cc { print $4 }
michael@0: 		' <$TZ_ZONE_TABLE)
michael@0: 
michael@0: 
michael@0: 		# If there's more than one region, ask the user which one.
michael@0: 		case $regions in
michael@0: 		*"$newline"*)
michael@0: 			echo >&2 'Please select one of the following' \
michael@0: 				'time zone regions.'
michael@0: 			select region in $regions
michael@0: 			do
michael@0: 				case $region in
michael@0: 				'') echo >&2 'Please enter a number in range.';;
michael@0: 				?*) break
michael@0: 				esac
michael@0: 			done
michael@0: 			case $region in
michael@0: 			'') exit 1
michael@0: 			esac;;
michael@0: 		*)
michael@0: 			region=$regions
michael@0: 		esac
michael@0: 
michael@0: 		# Determine TZ from country and region.
michael@0: 		TZ=$($AWK -F'\t' \
michael@0: 			-v country="$country" \
michael@0: 			-v region="$region" \
michael@0: 			-v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
michael@0: 		'
michael@0: 			BEGIN {
michael@0: 				cc = country
michael@0: 				while (getline <TZ_COUNTRY_TABLE) {
michael@0: 					if ($0 !~ /^#/  &&  country == $2) {
michael@0: 						cc = $1
michael@0: 						break
michael@0: 					}
michael@0: 				}
michael@0: 			}
michael@0: 			$1 == cc && $4 == region { print $3 }
michael@0: 		' <$TZ_ZONE_TABLE)
michael@0: 
michael@0: 		# Make sure the corresponding zoneinfo file exists.
michael@0: 		TZ_for_date=$TZDIR/$TZ
michael@0: 		<$TZ_for_date || {
michael@0: 			echo >&2 "$0: time zone files are not set up correctly"
michael@0: 			exit 1
michael@0: 		}
michael@0: 	esac
michael@0: 
michael@0: 
michael@0: 	# Use the proposed TZ to output the current date relative to UTC.
michael@0: 	# Loop until they agree in seconds.
michael@0: 	# Give up after 8 unsuccessful tries.
michael@0: 
michael@0: 	extra_info=
michael@0: 	for i in 1 2 3 4 5 6 7 8
michael@0: 	do
michael@0: 		TZdate=$(LANG=C TZ="$TZ_for_date" date)
michael@0: 		UTdate=$(LANG=C TZ=UTC0 date)
michael@0: 		TZsec=$(expr "$TZdate" : '.*:\([0-5][0-9]\)')
michael@0: 		UTsec=$(expr "$UTdate" : '.*:\([0-5][0-9]\)')
michael@0: 		case $TZsec in
michael@0: 		$UTsec)
michael@0: 			extra_info="
michael@0: Local time is now:	$TZdate.
michael@0: Universal Time is now:	$UTdate."
michael@0: 			break
michael@0: 		esac
michael@0: 	done
michael@0: 
michael@0: 
michael@0: 	# Output TZ info and ask the user to confirm.
michael@0: 
michael@0: 	echo >&2 ""
michael@0: 	echo >&2 "The following information has been given:"
michael@0: 	echo >&2 ""
michael@0: 	case $country+$region in
michael@0: 	?*+?*)	echo >&2 "	$country$newline	$region";;
michael@0: 	?*+)	echo >&2 "	$country";;
michael@0: 	+)	echo >&2 "	TZ='$TZ'"
michael@0: 	esac
michael@0: 	echo >&2 ""
michael@0: 	echo >&2 "Therefore TZ='$TZ' will be used.$extra_info"
michael@0: 	echo >&2 "Is the above information OK?"
michael@0: 
michael@0: 	ok=
michael@0: 	select ok in Yes No
michael@0: 	do
michael@0: 	    case $ok in
michael@0: 	    '') echo >&2 'Please enter 1 for Yes, or 2 for No.';;
michael@0: 	    ?*) break
michael@0: 	    esac
michael@0: 	done
michael@0: 	case $ok in
michael@0: 	'') exit 1;;
michael@0: 	Yes) break
michael@0: 	esac
michael@0: do :
michael@0: done
michael@0: 
michael@0: case $SHELL in
michael@0: *csh) file=.login line="setenv TZ '$TZ'";;
michael@0: *) file=.profile line="TZ='$TZ'; export TZ"
michael@0: esac
michael@0: 
michael@0: echo >&2 "
michael@0: You can make this change permanent for yourself by appending the line
michael@0: 	$line
michael@0: to the file '$file' in your home directory; then log out and log in again.
michael@0: 
michael@0: Here is that TZ value again, this time on standard output so that you
michael@0: can use the $0 command in shell scripts:"
michael@0: 
michael@0: echo "$TZ"