summaryrefslogtreecommitdiff
path: root/timezone/tzselect.ksh
blob: 8e66b4427355940e3b827e4f990270c992729dc1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
#!/bin/bash

PKGVERSION='(tzcode) '
TZVERSION=see_Makefile
REPORT_BUGS_TO=tz@iana.org

# Ask the user about the time zone, and output the resulting TZ value to stdout.
# Interact with the user via stderr and stdin.

# Contributed by Paul Eggert.

# Porting notes:
#
# This script requires a Posix-like shell with the extension of a
# 'select' statement.  The 'select' statement was introduced in the
# Korn shell and is available in Bash and other shell implementations.
# If your host lacks both Bash and the Korn shell, you can get their
# source from one of these locations:
#
#	Bash <http://www.gnu.org/software/bash/bash.html>
#	Korn Shell <http://www.kornshell.com/>
#	Public Domain Korn Shell <http://www.cs.mun.ca/~michael/pdksh/>
#
# This script also uses several features of modern awk programs.
# If your host lacks awk, or has an old awk that does not conform to Posix,
# you can use either of the following free programs instead:
#
#	Gawk (GNU awk) <http://www.gnu.org/software/gawk/>
#	mawk <http://invisible-island.net/mawk/>


# Specify default values for environment variables if they are unset.
: ${AWK=awk}
: ${TZDIR=$(pwd)}

# Check for awk Posix compliance.
($AWK -v x=y 'BEGIN { exit 123 }') </dev/null >/dev/null 2>&1
[ $? = 123 ] || {
	echo >&2 "$0: Sorry, your \`$AWK' program is not Posix compatible."
	exit 1
}

if [ "$1" = "--help" ]; then
    cat <<EOF
Usage: tzselect
Select a time zone interactively.

Report bugs to $REPORT_BUGS_TO.
EOF
    exit
elif [ "$1" = "--version" ]; then
    cat <<EOF
tzselect $PKGVERSION$TZVERSION
EOF
    exit
fi

# Make sure the tables are readable.
TZ_COUNTRY_TABLE=$TZDIR/iso3166.tab
TZ_ZONE_TABLE=$TZDIR/zone.tab
for f in $TZ_COUNTRY_TABLE $TZ_ZONE_TABLE
do
	<$f || {
		echo >&2 "$0: time zone files are not set up correctly"
		exit 1
	}
done

newline='
'
IFS=$newline


# Work around a bug in bash 1.14.7 and earlier, where $PS3 is sent to stdout.
case $(echo 1 | (select x in x; do break; done) 2>/dev/null) in
?*) PS3=
esac


# Begin the main loop.  We come back here if the user wants to retry.
while

	echo >&2 'Please identify a location' \
		'so that time zone rules can be set correctly.'

	continent=
	country=
	region=


	# Ask the user for continent or ocean.

	echo >&2 'Please select a continent or ocean.'

	select continent in \
	    Africa \
	    Americas \
	    Antarctica \
	    'Arctic Ocean' \
	    Asia \
	    'Atlantic Ocean' \
	    Australia \
	    Europe \
	    'Indian Ocean' \
	    'Pacific Ocean' \
	    'none - I want to specify the time zone using the Posix TZ format.'
	do
	    case $continent in
	    '')
		echo >&2 'Please enter a number in range.';;
	    ?*)
		case $continent in
		Americas) continent=America;;
		*' '*) continent=$(expr "$continent" : '\([^ ]*\)')
		esac
		break
	    esac
	done
	case $continent in
	'')
		exit 1;;
	none)
		# Ask the user for a Posix TZ string.  Check that it conforms.
		while
			echo >&2 'Please enter the desired value' \
				'of the TZ environment variable.'
			echo >&2 'For example, GST-10 is a zone named GST' \
				'that is 10 hours ahead (east) of UTC.'
			read TZ
			$AWK -v TZ="$TZ" 'BEGIN {
				tzname = "[^-+,0-9][^-+,0-9][^-+,0-9]+"
				time = "[0-2]?[0-9](:[0-5][0-9](:[0-5][0-9])?)?"
				offset = "[-+]?" time
				date = "(J?[0-9]+|M[0-9]+\.[0-9]+\.[0-9]+)"
				datetime = "," date "(/" time ")?"
				tzpattern = "^(:.*|" tzname offset "(" tzname \
				  "(" offset ")?(" datetime datetime ")?)?)$"
				if (TZ ~ tzpattern) exit 1
				exit 0
			}'
		do
			echo >&2 "\`$TZ' is not a conforming" \
				'Posix time zone string.'
		done
		TZ_for_date=$TZ;;
	*)
		# Get list of names of countries in the continent or ocean.
		countries=$($AWK -F'\t' \
			-v continent="$continent" \
			-v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
		'
			/^#/ { next }
			$3 ~ ("^" continent "/") {
				if (!cc_seen[$1]++) cc_list[++ccs] = $1
			}
			END {
				while (getline <TZ_COUNTRY_TABLE) {
					if ($0 !~ /^#/) cc_name[$1] = $2
				}
				for (i = 1; i <= ccs; i++) {
					country = cc_list[i]
					if (cc_name[country]) {
					  country = cc_name[country]
					}
					print country
				}
			}
		' <$TZ_ZONE_TABLE | sort -f)


		# If there's more than one country, ask the user which one.
		case $countries in
		*"$newline"*)
			echo >&2 'Please select a country.'
			select country in $countries
			do
			    case $country in
			    '') echo >&2 'Please enter a number in range.';;
			    ?*) break
			    esac
			done

			case $country in
			'') exit 1
			esac;;
		*)
			country=$countries
		esac


		# Get list of names of time zone rule regions in the country.
		regions=$($AWK -F'\t' \
			-v country="$country" \
			-v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
		'
			BEGIN {
				cc = country
				while (getline <TZ_COUNTRY_TABLE) {
					if ($0 !~ /^#/  &&  country == $2) {
						cc = $1
						break
					}
				}
			}
			$1 == cc { print $4 }
		' <$TZ_ZONE_TABLE)


		# If there's more than one region, ask the user which one.
		case $regions in
		*"$newline"*)
			echo >&2 'Please select one of the following' \
				'time zone regions.'
			select region in $regions
			do
				case $region in
				'') echo >&2 'Please enter a number in range.';;
				?*) break
				esac
			done
			case $region in
			'') exit 1
			esac;;
		*)
			region=$regions
		esac

		# Determine TZ from country and region.
		TZ=$($AWK -F'\t' \
			-v country="$country" \
			-v region="$region" \
			-v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
		'
			BEGIN {
				cc = country
				while (getline <TZ_COUNTRY_TABLE) {
					if ($0 !~ /^#/  &&  country == $2) {
						cc = $1
						break
					}
				}
			}
			$1 == cc && $4 == region { print $3 }
		' <$TZ_ZONE_TABLE)

		# Make sure the corresponding zoneinfo file exists.
		TZ_for_date=$TZDIR/$TZ
		<$TZ_for_date || {
			echo >&2 "$0: time zone files are not set up correctly"
			exit 1
		}
	esac


	# Use the proposed TZ to output the current date relative to UTC.
	# Loop until they agree in seconds.
	# Give up after 8 unsuccessful tries.

	extra_info=
	for i in 1 2 3 4 5 6 7 8
	do
		TZdate=$(LANG=C TZ="$TZ_for_date" date)
		UTdate=$(LANG=C TZ=UTC0 date)
		TZsec=$(expr "$TZdate" : '.*:\([0-5][0-9]\)')
		UTsec=$(expr "$UTdate" : '.*:\([0-5][0-9]\)')
		case $TZsec in
		$UTsec)
			extra_info="
Local time is now:	$TZdate.
Universal Time is now:	$UTdate."
			break
		esac
	done


	# Output TZ info and ask the user to confirm.

	echo >&2 ""
	echo >&2 "The following information has been given:"
	echo >&2 ""
	case $country+$region in
	?*+?*)	echo >&2 "	$country$newline	$region";;
	?*+)	echo >&2 "	$country";;
	+)	echo >&2 "	TZ='$TZ'"
	esac
	echo >&2 ""
	echo >&2 "Therefore TZ='$TZ' will be used.$extra_info"
	echo >&2 "Is the above information OK?"

	ok=
	select ok in Yes No
	do
	    case $ok in
	    '') echo >&2 'Please enter 1 for Yes, or 2 for No.';;
	    ?*) break
	    esac
	done
	case $ok in
	'') exit 1;;
	Yes) break
	esac
do :
done

case $SHELL in
*csh) file=.login line="setenv TZ '$TZ'";;
*) file=.profile line="TZ='$TZ'; export TZ"
esac

echo >&2 "
You can make this change permanent for yourself by appending the line
	$line
to the file '$file' in your home directory; then log out and log in again.

Here is that TZ value again, this time on standard output so that you
can use the $0 command in shell scripts:"

echo "$TZ"