293 lines
6.4 KiB
Bash
293 lines
6.4 KiB
Bash
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#! /bin/ksh
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# Ask the user about the time zone, and output the resulting TZ value to stdout.
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# Interact with the user via stderr and stdin.
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# Contributed by Paul Eggert <eggert@twinsun.com>.
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# Porting notes:
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#
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# This script requires several features of the Korn shell.
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# If your host lacks the Korn shell,
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# you can use either of the following free programs instead:
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#
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# Bourne-Again shell (bash)
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# <URL:ftp://prep.ai.mit.edu:/pub/gnu/bash-1.14.7.tar.gz>
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# (or any later version)
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#
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# Public domain ksh
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# <URL:ftp://ftp.cs.mun.ca:/pub/pdksh/pdksh.tar.gz>
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#
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# This script also uses several features of modern awk programs.
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# If your host lacks awk, or has an old awk that does not conform to Posix.2,
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# you can use either of the following free programs instead:
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#
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# GNU awk (gawk)
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# <URL:ftp://prep.ai.mit.edu:/pub/gnu/gawk-3.0.0.tar.gz>
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# (or any later version)
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#
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# mawk
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# <URL:ftp://oxy.edu/public/mawk1.2.2.tar.gz>
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# (or any later version)
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# Specify default values for environment variables if they are unset.
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: ${AWK=awk}
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: ${TZDIR=$(pwd)}
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# Check for awk Posix compliance.
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($AWK -v x=y 'BEGIN { exit 123 }') </dev/null >/dev/null 2>&1
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[ $? = 123 ] || {
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echo >&2 "$0: Sorry, your \`$AWK' program is not Posix compatible."
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exit 1
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}
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# Make sure the tables are readable.
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TZ_COUNTRY_TABLE=$TZDIR/iso3166.tab
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TZ_ZONE_TABLE=$TZDIR/zone.tab
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for f in $TZ_COUNTRY_TABLE $TZ_ZONE_TABLE
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do
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<$f || {
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echo >&2 "$0: time zone files are not set up correctly"
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exit 1
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}
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done
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newline='
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'
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IFS=$newline
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# Work around a bash bug, where $PS3 is sent to stdout.
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case $(echo 1 | (select x in x; do break; done) 2>/dev/null) in
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?*) PS3=
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esac
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# Begin the main loop. We come back here if the user wants to retry.
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while
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echo >&2 'Please identify a location' \
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'so that time zone rules can be set correctly.'
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continent=
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country=
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region=
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# Ask the user for continent or ocean.
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echo >&2 'Please select a continent or ocean.'
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select continent in \
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Africa \
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Americas \
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Antarctica \
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'Arctic Ocean' \
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Asia \
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'Atlantic Ocean' \
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Australia \
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Europe \
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'Indian Ocean' \
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'Pacific Ocean' \
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'none - I want to specify the time zone using the Posix TZ format.'
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do
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case $continent in
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'')
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echo >&2 'Please enter a number in range.';;
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?*)
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case $continent in
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Americas) continent=America;;
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*' '*) continent=$(expr "$continent" : '\([^ ]*\)')
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esac
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break
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esac
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done
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case $continent in
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'')
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exit 1;;
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none)
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# Ask the user for a Posix TZ string. Check that it conforms.
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while
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echo >&2 'Please enter the desired value' \
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'of the TZ environment variable.'
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echo >&2 'For example, GST-10 is a zone named GST' \
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'that is 10 hours ahead (east) of UTC.'
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read TZ
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$AWK -v TZ="$TZ" 'BEGIN {
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tzname = "[^-+,0-9][^-+,0-9][^-+,0-9]+"
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time = "[0-2]?[0-9](:[0-5][0-9](:[0-5][0-9])?)?"
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offset = "[-+]?" time
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date = "(J?[0-9]+|M[0-9]+\.[0-9]+\.[0-9]+)"
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datetime = "," date "(/" time ")?"
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tzpattern = "^(:.*|" tzname offset "(" tzname \
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"(" offset ")?(" datetime datetime ")?)?)$"
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if (TZ ~ tzpattern) exit 1
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exit 0
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}'
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do
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echo >&2 "\`$TZ' is not a conforming" \
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'Posix time zone string.'
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done
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TZ_for_date=$TZ;;
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*)
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# Get list of names of countries in the continent or ocean.
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countries=$($AWK -F'\t' \
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-v continent="$continent" \
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-v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
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'
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/^#/ { next }
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$3 ~ ("^" continent "/") {
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if (!cc_seen[$1]++) cc_list[++ccs] = $1
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}
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END {
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while (getline <TZ_COUNTRY_TABLE) {
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if ($0 !~ /^#/) cc_name[$1] = $2
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}
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for (i = 1; i <= ccs; i++) {
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country = cc_list[i]
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if (cc_name[country]) {
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country = cc_name[country]
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}
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print country
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}
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}
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' <$TZ_ZONE_TABLE | sort -f)
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# If there's more than one country, ask the user which one.
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case $countries in
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*"$newline"*)
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echo >&2 'Please select a country.'
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select country in $countries
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do
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case $country in
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'') echo >&2 'Please enter a number in range.';;
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?*) break
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esac
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done
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case $country in
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'') exit 1
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esac;;
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*)
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country=$countries
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esac
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# Get list of names of time zone rule regions in the country.
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regions=$($AWK -F'\t' \
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-v country="$country" \
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-v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
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'
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BEGIN {
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cc = country
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while (getline <TZ_COUNTRY_TABLE) {
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if ($0 !~ /^#/ && country == $2) {
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cc = $1
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break
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}
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}
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}
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$1 == cc { print $4 }
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' <$TZ_ZONE_TABLE)
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# If there's more than one region, ask the user which one.
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case $regions in
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*"$newline"*)
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echo >&2 'Please select one of the following' \
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'time zone regions.'
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select region in $regions
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do
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case $region in
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'') echo >&2 'Please enter a number in range.';;
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?*) break
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esac
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done
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case $region in
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'') exit 1
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esac;;
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*)
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region=$regions
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esac
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# Determine TZ from country and region.
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TZ=$($AWK -F'\t' \
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-v country="$country" \
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-v region="$region" \
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-v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
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'
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BEGIN {
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cc = country
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while (getline <TZ_COUNTRY_TABLE) {
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if ($0 !~ /^#/ && country == $2) {
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cc = $1
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break
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}
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}
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}
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$1 == cc && $4 == region { print $3 }
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' <$TZ_ZONE_TABLE)
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# Make sure the corresponding zoneinfo file exists.
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TZ_for_date=$TZDIR/$TZ
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<$TZ_for_date || {
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echo >&2 "$0: time zone files are not set up correctly"
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exit 1
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}
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esac
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# Use the proposed TZ to output the current date relative to UTC.
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# Loop until they agree in seconds.
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# Give up after 8 unsuccessful tries.
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extra_info=
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for i in 1 2 3 4 5 6 7 8
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do
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TZdate=$(LANG=C TZ="$TZ_for_date" date)
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UTdate=$(LANG=C TZ=UTC0 date)
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TZsec=$(expr "$TZdate" : '.*:\([0-5][0-9]\)')
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UTsec=$(expr "$UTdate" : '.*:\([0-5][0-9]\)')
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case $TZsec in
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$UTsec)
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extra_info="
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Local time is now: $TZdate.
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Universal Time is now: $UTdate."
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break
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esac
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done
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# Output TZ info and ask the user to confirm.
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echo >&2 ""
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echo >&2 "The following information has been given:"
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echo >&2 ""
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case $country+$region in
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?*+?*) echo >&2 " $country$newline $region";;
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?*+) echo >&2 " $country";;
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+) echo >&2 " TZ='$TZ'"
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esac
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echo >&2 ""
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echo >&2 "Therefore TZ='$TZ' will be used.$extra_info"
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echo >&2 "Is the above information OK?"
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ok=
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select ok in Yes No
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do
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case $ok in
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'') echo >&2 'Please enter 1 for Yes, or 2 for No.';;
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?*) break
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esac
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done
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case $ok in
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'') exit 1;;
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Yes) break
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esac
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do :
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done
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# Output the answer.
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echo "$TZ"
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