1#! /bin/ksh
2
3# '@(#)tzselect.ksh	8.1'
4
5# Ask the user about the time zone, and output the resulting TZ value to stdout.
6# Interact with the user via stderr and stdin.
7
8# Contributed by Paul Eggert.
9
10# Porting notes:
11#
12# This script requires several features of the Korn shell.
13# If your host lacks the Korn shell,
14# you can use either of the following free programs instead:
15#
16#	<a href=ftp://ftp.gnu.org/pub/gnu/>
17#	Bourne-Again shell (bash)
18#	</a>
19#
20#	<a href=ftp://ftp.cs.mun.ca/pub/pdksh/pdksh.tar.gz>
21#	Public domain ksh
22#	</a>
23#
24# This script also uses several features of modern awk programs.
25# If your host lacks awk, or has an old awk that does not conform to Posix.2,
26# you can use either of the following free programs instead:
27#
28#	<a href=ftp://ftp.gnu.org/pub/gnu/>
29#	GNU awk (gawk)
30#	</a>
31#
32#	<a href=ftp://ftp.whidbey.net/pub/brennan/>
33#	mawk
34#	</a>
35
36
37# Specify default values for environment variables if they are unset.
38: ${AWK=awk}
39: ${TZDIR=$(pwd)}
40
41# Check for awk Posix compliance.
42($AWK -v x=y 'BEGIN { exit 123 }') </dev/null >/dev/null 2>&1
43[ $? = 123 ] || {
44	echo >&2 "$0: Sorry, your \`$AWK' program is not Posix compatible."
45	exit 1
46}
47
48# Make sure the tables are readable.
49TZ_COUNTRY_TABLE=$TZDIR/iso3166.tab
50TZ_ZONE_TABLE=$TZDIR/zone.tab
51for f in $TZ_COUNTRY_TABLE $TZ_ZONE_TABLE
52do
53	<$f || {
54		echo >&2 "$0: time zone files are not set up correctly"
55		exit 1
56	}
57done
58
59newline='
60'
61IFS=$newline
62
63
64# Work around a bug in bash 1.14.7 and earlier, where $PS3 is sent to stdout.
65case $(echo 1 | (select x in x; do break; done) 2>/dev/null) in
66?*) PS3=
67esac
68
69
70# Begin the main loop.  We come back here if the user wants to retry.
71while
72
73	echo >&2 'Please identify a location' \
74		'so that time zone rules can be set correctly.'
75
76	continent=
77	country=
78	region=
79
80
81	# Ask the user for continent or ocean.
82
83	echo >&2 'Please select a continent or ocean.'
84
85	select continent in \
86	    Africa \
87	    Americas \
88	    Antarctica \
89	    'Arctic Ocean' \
90	    Asia \
91	    'Atlantic Ocean' \
92	    Australia \
93	    Europe \
94	    'Indian Ocean' \
95	    'Pacific Ocean' \
96	    'none - I want to specify the time zone using the Posix TZ format.'
97	do
98	    case $continent in
99	    '')
100		echo >&2 'Please enter a number in range.';;
101	    ?*)
102		case $continent in
103		Americas) continent=America;;
104		*' '*) continent=$(expr "$continent" : '\([^ ]*\)')
105		esac
106		break
107	    esac
108	done
109	case $continent in
110	'')
111		exit 1;;
112	none)
113		# Ask the user for a Posix TZ string.  Check that it conforms.
114		while
115			echo >&2 'Please enter the desired value' \
116				'of the TZ environment variable.'
117			echo >&2 'For example, GST-10 is a zone named GST' \
118				'that is 10 hours ahead (east) of UTC.'
119			read TZ
120			$AWK -v TZ="$TZ" 'BEGIN {
121				tzname = "[^-+,0-9][^-+,0-9][^-+,0-9]+"
122				time = "[0-2]?[0-9](:[0-5][0-9](:[0-5][0-9])?)?"
123				offset = "[-+]?" time
124				date = "(J?[0-9]+|M[0-9]+\.[0-9]+\.[0-9]+)"
125				datetime = "," date "(/" time ")?"
126				tzpattern = "^(:.*|" tzname offset "(" tzname \
127				  "(" offset ")?(" datetime datetime ")?)?)$"
128				if (TZ ~ tzpattern) exit 1
129				exit 0
130			}'
131		do
132			echo >&2 "\`$TZ' is not a conforming" \
133				'Posix time zone string.'
134		done
135		TZ_for_date=$TZ;;
136	*)
137		# Get list of names of countries in the continent or ocean.
138		countries=$($AWK -F'\t' \
139			-v continent="$continent" \
140			-v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
141		'
142			/^#/ { next }
143			$3 ~ ("^" continent "/") {
144				if (!cc_seen[$1]++) cc_list[++ccs] = $1
145			}
146			END {
147				while (getline <TZ_COUNTRY_TABLE) {
148					if ($0 !~ /^#/) cc_name[$1] = $2
149				}
150				for (i = 1; i <= ccs; i++) {
151					country = cc_list[i]
152					if (cc_name[country]) {
153					  country = cc_name[country]
154					}
155					print country
156				}
157			}
158		' <$TZ_ZONE_TABLE | sort -f)
159
160
161		# If there's more than one country, ask the user which one.
162		case $countries in
163		*"$newline"*)
164			echo >&2 'Please select a country.'
165			select country in $countries
166			do
167			    case $country in
168			    '') echo >&2 'Please enter a number in range.';;
169			    ?*) break
170			    esac
171			done
172
173			case $country in
174			'') exit 1
175			esac;;
176		*)
177			country=$countries
178		esac
179
180
181		# Get list of names of time zone rule regions in the country.
182		regions=$($AWK -F'\t' \
183			-v country="$country" \
184			-v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
185		'
186			BEGIN {
187				cc = country
188				while (getline <TZ_COUNTRY_TABLE) {
189					if ($0 !~ /^#/  &&  country == $2) {
190						cc = $1
191						break
192					}
193				}
194			}
195			$1 == cc { print $4 }
196		' <$TZ_ZONE_TABLE)
197
198
199		# If there's more than one region, ask the user which one.
200		case $regions in
201		*"$newline"*)
202			echo >&2 'Please select one of the following' \
203				'time zone regions.'
204			select region in $regions
205			do
206				case $region in
207				'') echo >&2 'Please enter a number in range.';;
208				?*) break
209				esac
210			done
211			case $region in
212			'') exit 1
213			esac;;
214		*)
215			region=$regions
216		esac
217
218		# Determine TZ from country and region.
219		TZ=$($AWK -F'\t' \
220			-v country="$country" \
221			-v region="$region" \
222			-v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
223		'
224			BEGIN {
225				cc = country
226				while (getline <TZ_COUNTRY_TABLE) {
227					if ($0 !~ /^#/  &&  country == $2) {
228						cc = $1
229						break
230					}
231				}
232			}
233			$1 == cc && $4 == region { print $3 }
234		' <$TZ_ZONE_TABLE)
235
236		# Make sure the corresponding zoneinfo file exists.
237		TZ_for_date=$TZDIR/$TZ
238		<$TZ_for_date || {
239			echo >&2 "$0: time zone files are not set up correctly"
240			exit 1
241		}
242	esac
243
244
245	# Use the proposed TZ to output the current date relative to UTC.
246	# Loop until they agree in seconds.
247	# Give up after 8 unsuccessful tries.
248
249	extra_info=
250	for i in 1 2 3 4 5 6 7 8
251	do
252		TZdate=$(LANG=C TZ="$TZ_for_date" date)
253		UTdate=$(LANG=C TZ=UTC0 date)
254		TZsec=$(expr "$TZdate" : '.*:\([0-5][0-9]\)')
255		UTsec=$(expr "$UTdate" : '.*:\([0-5][0-9]\)')
256		case $TZsec in
257		$UTsec)
258			extra_info="
259Local time is now:	$TZdate.
260Universal Time is now:	$UTdate."
261			break
262		esac
263	done
264
265
266	# Output TZ info and ask the user to confirm.
267
268	echo >&2 ""
269	echo >&2 "The following information has been given:"
270	echo >&2 ""
271	case $country+$region in
272	?*+?*)	echo >&2 "	$country$newline	$region";;
273	?*+)	echo >&2 "	$country";;
274	+)	echo >&2 "	TZ='$TZ'"
275	esac
276	echo >&2 ""
277	echo >&2 "Therefore TZ='$TZ' will be used.$extra_info"
278	echo >&2 "Is the above information OK?"
279
280	ok=
281	select ok in Yes No
282	do
283	    case $ok in
284	    '') echo >&2 'Please enter 1 for Yes, or 2 for No.';;
285	    ?*) break
286	    esac
287	done
288	case $ok in
289	'') exit 1;;
290	Yes) break
291	esac
292do :
293done
294
295case $SHELL in
296*csh) file=.login line="setenv TZ '$TZ'";;
297*) file=.profile line="TZ='$TZ'; export TZ"
298esac
299
300echo >&2 "
301You can make this change permanent for yourself by appending the line
302	$line
303to the file '$file' in your home directory; then log out and log in again.
304
305Here is that TZ value again, this time on standard output so that you
306can use the $0 command in shell scripts:"
307
308echo "$TZ"
309