Preview: tzselect
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/bin/tzselect
#!/usr/bin/bash
# Ask the user about the time zone, and output the resulting TZ value to stdout.
# Interact with the user via stderr and stdin.
PKGVERSION="(GNU libc) "
TZVERSION="2.34"
REPORT_BUGS_TO="<https://www.gnu.org/software/libc/bugs.html>"
# Contributed by Paul Eggert. This file is in the public domain.
# Porting notes:
#
# This script requires a Posix-like shell and prefers 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 <https://www.gnu.org/software/bash/>
# Korn Shell <http://www.kornshell.com/>
# MirBSD Korn Shell <https://www.mirbsd.org/mksh.htm>
#
# For portability to Solaris 9 /bin/sh this script avoids some POSIX
# features and common extensions, such as $(...) (which works sometimes
# but not others), $((...)), and $10.
#
# 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) <https://www.gnu.org/software/gawk/>
# mawk <https://invisible-island.net/mawk/>
# Specify default values for environment variables if they are unset.
: ${AWK=awk}
: ${TZDIR=/usr/share/zoneinfo}
# Output one argument as-is to standard output.
# Safer than 'echo', which can mishandle '\' or leading '-'.
say() {
printf '%s\n' "$1"
}
# Check for awk Posix compliance.
($AWK -v x=y 'BEGIN { exit 123 }') </dev/null >/dev/null 2>&1
[ $? = 123 ] || {
say >&2 "$0: Sorry, your '$AWK' program is not Posix compatible."
exit 1
}
coord=
location_limit=10
zonetabtype=zone1970
usage="Usage: tzselect [--version] [--help] [-c COORD] [-n LIMIT]
Select a timezone interactively.
Options:
-c COORD
Instead of asking for continent and then country and then city,
ask for selection from time zones whose largest cities
are closest to the location with geographical coordinates COORD.
COORD should use ISO 6709 notation, for example, '-c +4852+00220'
for Paris (in degrees and minutes, North and East), or
'-c -35-058' for Buenos Aires (in degrees, South and West).
-n LIMIT
Display at most LIMIT locations when -c is used (default $location_limit).
--version
Output version information.
--help
Output this help.
Report bugs to $REPORT_BUGS_TO."
# Ask the user to select from the function's arguments,
# and assign the selected argument to the variable 'select_result'.
# Exit on EOF or I/O error. Use the shell's 'select' builtin if available,
# falling back on a less-nice but portable substitute otherwise.
if
case $BASH_VERSION in
?*) : ;;
'')
# '; exit' should be redundant, but Dash doesn't properly fail without it.
(eval 'set --; select x; do break; done; exit') </dev/null 2>/dev/null
esac
then
# Do this inside 'eval', as otherwise the shell might exit when parsing it
# even though it is never executed.
eval '
doselect() {
select select_result
do
case $select_result in
"") echo >&2 "Please enter a number in range." ;;
?*) break
esac
done || exit
}
# Work around a bug in bash 1.14.7 and earlier, where $PS3 is sent to stdout.
case $BASH_VERSION in
[01].*)
case `echo 1 | (select x in x; do break; done) 2>/dev/null` in
?*) PS3=
esac
esac
'
else
doselect() {
# Field width of the prompt numbers.
select_width=`expr $# : '.*'`
select_i=
while :
do
case $select_i in
'')
select_i=0
for select_word
do
select_i=`expr $select_i + 1`
printf >&2 "%${select_width}d) %s\\n" $select_i "$select_word"
done ;;
*[!0-9]*)
echo >&2 'Please enter a number in range.' ;;
*)
if test 1 -le $select_i && test $select_i -le $#; then
shift `expr $select_i - 1`
select_result=$1
break
fi
echo >&2 'Please enter a number in range.'
esac
# Prompt and read input.
printf >&2 %s "${PS3-#? }"
read select_i || exit
done
}
fi
while getopts c:n:t:-: opt
do
case $opt$OPTARG in
c*)
coord=$OPTARG ;;
n*)
location_limit=$OPTARG ;;
t*) # Undocumented option, used for developer testing.
zonetabtype=$OPTARG ;;
-help)
exec echo "$usage" ;;
-version)
exec echo "tzselect $PKGVERSION$TZVERSION" ;;
-*)
say >&2 "$0: -$opt$OPTARG: unknown option; try '$0 --help'"; exit 1 ;;
*)
say >&2 "$0: try '$0 --help'"; exit 1 ;;
esac
done
shift `expr $OPTIND - 1`
case $# in
0) ;;
*) say >&2 "$0: $1: unknown argument"; exit 1 ;;
esac
# Make sure the tables are readable.
TZ_COUNTRY_TABLE=$TZDIR/iso3166.tab
TZ_ZONE_TABLE=$TZDIR/$zonetabtype.tab
for f in $TZ_COUNTRY_TABLE $TZ_ZONE_TABLE
do
<"$f" || {
say >&2 "$0: time zone files are not set up correctly"
exit 1
}
done
# If the current locale does not support UTF-8, convert data to current
# locale's format if possible, as the shell aligns columns better that way.
# Check the UTF-8 of U+12345 CUNEIFORM SIGN URU TIMES KI.
! $AWK 'BEGIN { u12345 = "\360\222\215\205"; exit length(u12345) != 1 }' &&
{ tmp=`(mktemp -d) 2>/dev/null` || {
tmp=${TMPDIR-/tmp}/tzselect.$$ &&
(umask 77 && mkdir -- "$tmp")
};} &&
trap 'status=$?; rm -fr -- "$tmp"; exit $status' 0 HUP INT PIPE TERM &&
(iconv -f UTF-8 -t //TRANSLIT <"$TZ_COUNTRY_TABLE" >$tmp/iso3166.tab) \
2>/dev/null &&
TZ_COUNTRY_TABLE=$tmp/iso3166.tab &&
iconv -f UTF-8 -t //TRANSLIT <"$TZ_ZONE_TABLE" >$tmp/$zonetabtype.tab &&
TZ_ZONE_TABLE=$tmp/$zonetabtype.tab
newline='
'
IFS=$newline
# Awk script to read a time zone table and output the same table,
# with each column preceded by its distance from 'here'.
output_distances='
BEGIN {
FS = "\t"
while (getline <TZ_COUNTRY_TABLE)
if ($0 ~ /^[^#]/)
country[$1] = $2
country["US"] = "US" # Otherwise the strings get too long.
}
function abs(x) {
return x < 0 ? -x : x;
}
function min(x, y) {
return x < y ? x : y;
}
function convert_coord(coord, deg, minute, ilen, sign, sec) {
if (coord ~ /^[-+]?[0-9]?[0-9][0-9][0-9][0-9][0-9][0-9]([^0-9]|$)/) {
degminsec = coord
intdeg = degminsec < 0 ? -int(-degminsec / 10000) : int(degminsec / 10000)
minsec = degminsec - intdeg * 10000
intmin = minsec < 0 ? -int(-minsec / 100) : int(minsec / 100)
sec = minsec - intmin * 100
deg = (intdeg * 3600 + intmin * 60 + sec) / 3600
} else if (coord ~ /^[-+]?[0-9]?[0-9][0-9][0-9][0-9]([^0-9]|$)/) {
degmin = coord
intdeg = degmin < 0 ? -int(-degmin / 100) : int(degmin / 100)
minute = degmin - intdeg * 100
deg = (intdeg * 60 + minute) / 60
} else
deg = coord
return deg * 0.017453292519943296
}
function convert_latitude(coord) {
match(coord, /..*[-+]/)
return convert_coord(substr(coord, 1, RLENGTH - 1))
}
function convert_longitude(coord) {
match(coord, /..*[-+]/)
return convert_coord(substr(coord, RLENGTH))
}
# Great-circle distance between points with given latitude and longitude.
# Inputs and output are in radians. This uses the great-circle special
# case of the Vicenty formula for distances on ellipsoids.
function gcdist(lat1, long1, lat2, long2, dlong, x, y, num, denom) {
dlong = long2 - long1
x = cos(lat2) * sin(dlong)
y = cos(lat1) * sin(lat2) - sin(lat1) * cos(lat2) * cos(dlong)
num = sqrt(x * x + y * y)
denom = sin(lat1) * sin(lat2) + cos(lat1) * cos(lat2) * cos(dlong)
return atan2(num, denom)
}
# Parallel distance between points with given latitude and longitude.
# This is the product of the longitude difference and the cosine
# of the latitude of the point that is further from the equator.
# I.e., it considers longitudes to be further apart if they are
# nearer the equator.
function pardist(lat1, long1, lat2, long2) {
return abs(long1 - long2) * min(cos(lat1), cos(lat2))
}
# The distance function is the sum of the great-circle distance and
# the parallel distance. It could be weighted.
function dist(lat1, long1, lat2, long2) {
return gcdist(lat1, long1, lat2, long2) + pardist(lat1, long1, lat2, long2)
}
BEGIN {
coord_lat = convert_latitude(coord)
coord_long = convert_longitude(coord)
}
/^[^#]/ {
here_lat = convert_latitude($2)
here_long = convert_longitude($2)
line = $1 "\t" $2 "\t" $3
sep = "\t"
ncc = split($1, cc, /,/)
for (i = 1; i <= ncc; i++) {
line = line sep country[cc[i]]
sep = ", "
}
if (NF == 4)
line = line " - " $4
printf "%g\t%s\n", dist(coord_lat, coord_long, here_lat, here_long), line
}
'
# 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=
case $coord in
?*)
continent=coord;;
'')
# Ask the user for continent or ocean.
echo >&2 'Please select a continent, ocean, "coord", or "TZ".'
quoted_continents=`
$AWK '
BEGIN { FS = "\t" }
/^[^#]/ {
entry = substr($3, 1, index($3, "/") - 1)
if (entry == "America")
entry = entry "s"
if (entry ~ /^(Arctic|Atlantic|Indian|Pacific)$/)
entry = entry " Ocean"
printf "'\''%s'\''\n", entry
}
' <"$TZ_ZONE_TABLE" |
sort -u |
tr '\n' ' '
echo ''
`
eval '
doselect '"$quoted_continents"' \
"coord - I want to use geographical coordinates." \
"TZ - I want to specify the timezone using the Posix TZ format."
continent=$select_result
case $continent in
Americas) continent=America;;
*" "*) continent=`expr "$continent" : '\''\([^ ]*\)'\''`
esac
'
esac
case $continent in
TZ)
# 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, AEST-10 is abbreviated' \
'AEST and is 10 hours'
echo >&2 'ahead (east) of Greenwich,' \
'with no daylight saving time.'
read TZ
$AWK -v TZ="$TZ" 'BEGIN {
tzname = "(<[[:alnum:]+-]{3,}>|[[:alpha:]]{3,})"
time = "(2[0-4]|[0-1]?[0-9])" \
"(:[0-5][0-9](:[0-5][0-9])?)?"
offset = "[-+]?" time
mdate = "M([1-9]|1[0-2])\\.[1-5]\\.[0-6]"
jdate = "((J[1-9]|[0-9]|J?[1-9][0-9]" \
"|J?[1-2][0-9][0-9])|J?3[0-5][0-9]|J?36[0-5])"
datetime = ",(" mdate "|" jdate ")(/" time ")?"
tzpattern = "^(:.*|" tzname offset "(" tzname \
"(" offset ")?(" datetime datetime ")?)?)$"
if (TZ ~ tzpattern) exit 1
exit 0
}'
do
say >&2 "'$TZ' is not a conforming Posix timezone string."
done
TZ_for_date=$TZ;;
*)
case $continent in
coord)
case $coord in
'')
echo >&2 'Please enter coordinates' \
'in ISO 6709 notation.'
echo >&2 'For example, +4042-07403 stands for'
echo >&2 '40 degrees 42 minutes north,' \
'74 degrees 3 minutes west.'
read coord;;
esac
distance_table=`$AWK \
-v coord="$coord" \
-v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
"$output_distances" <"$TZ_ZONE_TABLE" |
sort -n |
sed "${location_limit}q"
`
regions=`say "$distance_table" | $AWK '
BEGIN { FS = "\t" }
{ print $NF }
'`
echo >&2 'Please select one of the following timezones,' \
echo >&2 'listed roughly in increasing order' \
"of distance from $coord".
doselect $regions
region=$select_result
TZ=`say "$distance_table" | $AWK -v region="$region" '
BEGIN { FS="\t" }
$NF == region { print $4 }
'`
;;
*)
# Get list of names of countries in the continent or ocean.
countries=`$AWK \
-v continent="$continent" \
-v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
'
BEGIN { FS = "\t" }
/^#/ { next }
$3 ~ ("^" continent "/") {
ncc = split($1, cc, /,/)
for (i = 1; i <= ncc; i++)
if (!cc_seen[cc[i]]++) cc_list[++ccs] = cc[i]
}
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' \
'whose clocks agree with yours.'
doselect $countries
country=$select_result;;
*)
country=$countries
esac
# Get list of timezones in the country.
regions=`$AWK \
-v country="$country" \
-v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
'
BEGIN {
FS = "\t"
cc = country
while (getline <TZ_COUNTRY_TABLE) {
if ($0 !~ /^#/ && country == $2) {
cc = $1
break
}
}
}
/^#/ { next }
$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 timezones.'
doselect $regions
region=$select_result;;
*)
region=$regions
esac
# Determine TZ from country and region.
TZ=`$AWK \
-v country="$country" \
-v region="$region" \
-v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \
'
BEGIN {
FS = "\t"
cc = country
while (getline <TZ_COUNTRY_TABLE) {
if ($0 !~ /^#/ && country == $2) {
cc = $1
break
}
}
}
/^#/ { next }
$1 ~ cc && $4 == region { print $3 }
' <"$TZ_ZONE_TABLE"`
esac
# Make sure the corresponding zoneinfo file exists.
TZ_for_date=$TZDIR/$TZ
<"$TZ_for_date" || {
say >&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="
Selected 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%$coord in
?*%?*%) say >&2 " $country$newline $region";;
?*%%) say >&2 " $country";;
%?*%?*) say >&2 " coord $coord$newline $region";;
%%?*) say >&2 " coord $coord";;
*) say >&2 " TZ='$TZ'"
esac
say >&2 ""
say >&2 "Therefore TZ='$TZ' will be used.$extra_info"
say >&2 "Is the above information OK?"
doselect Yes No
ok=$select_result
case $ok in
Yes) break
esac
do coord=
done
case $SHELL in
*csh) file=.login line="setenv TZ '$TZ'";;
*) file=.profile line="TZ='$TZ'; export TZ"
esac
test -t 1 && say >&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 $0 command in shell scripts:"
say "$TZ"
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