#! /bin/ksh
# '@(#)tzselect.ksh 8.1'
# 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 several features of the Korn shell.
# If your host lacks the Korn shell,
# you can use either of the following free programs instead:
#
# <a href=ftp://ftp.gnu.org/pub/gnu/>
# Bourne-Again shell (bash)
# </a>
#
# <a href=ftp://ftp.cs.mun.ca/pub/pdksh/pdksh.tar.gz>
# Public domain ksh
# </a>
#
# 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.2,
# you can use either of the following free programs instead:
#
# <a href=ftp://ftp.gnu.org/pub/gnu/>
# GNU awk (gawk)
# </a>
#
# <a href=ftp://ftp.whidbey.net/pub/brennan/>
# mawk
# </a>
# 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
}
# 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"