From a8a44384c9186d2519c53b5561dd55555d409ab7 Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Mon, 16 Jan 2023 18:17:11 -0800 Subject: [PROPOSED 3/3] tzselect can now use current time to help choose Based on an idea mentioned by Peter Krefting in: https://mm.icann.org/pipermail/tz/2023-January/032516.html * NEWS: Mention this. * tzselect.ksh: Add support for this. (output_distances_or_times): Rename from output_distances. Accept new var output_times which says to output shell commands for a time table instead of outputting a distance table. Avoid duplicate items in the output line, something that is possible with time table (e.g., Crimea). --- NEWS | 4 ++ tzselect.ksh | 134 ++++++++++++++++++++++++++++++++++++++++----------- 2 files changed, 109 insertions(+), 29 deletions(-) diff --git a/NEWS b/NEWS index b2ada66..7bd8080 100644 --- a/NEWS +++ b/NEWS @@ -5,6 +5,7 @@ Unreleased, experimental changes Briefly: Much of Greenland still uses DST from 2024 on. America/Yellowknife now links to America/Edmonton. + tzselect can now use current time to help infer timezone. The code now defaults to C99 or later. Fix use of C23 attributes. @@ -27,6 +28,9 @@ Unreleased, experimental changes Changes to code + You can now tell tzselect local time, to simplify later choices. + Select the 'time' option in its first prompt. + The code by default is now designed for C99 or later. To build in a C89 environment, compile with -DPORT_TO_C89. To support C89 callers of the tzcode library, compile with -DSUPPORT_C89. The diff --git a/tzselect.ksh b/tzselect.ksh index bf24739..254656d 100644 --- a/tzselect.ksh +++ b/tzselect.ksh @@ -244,14 +244,16 @@ output_country_list=' ' # Awk script to read a time zone table and output the same table, -# with each column preceded by its distance from 'here'. -output_distances=' +# with each column preceded by its distance from 'here' or by its local time. +output_distances_or_times=' BEGIN { FS = "\t" - while (getline &2 'Please select a continent, ocean, "coord", or "TZ".' + echo >&2 'Please select a continent, ocean, "coord", "TZ", or "time".' quoted_continents=` $AWK ' @@ -385,7 +395,8 @@ while eval ' doselect '"$quoted_continents"' \ "coord - I want to use geographical coordinates." \ - "TZ - I want to specify the timezone using the Posix TZ format." + "TZ - I want to specify the timezone using the Posix TZ format." \ + "time - I know local time already." continent=$select_result case $continent in Americas) continent=America;; @@ -438,7 +449,7 @@ while distance_table=`$AWK \ -v coord="$coord" \ -v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \ - "$output_distances" <"$TZ_ZONE_TABLE" | + "$output_distances_or_times" <"$TZ_ZONE_TABLE" | sort -n | sed "${location_limit}q" ` @@ -472,13 +483,63 @@ while '` ;; *) - # Get list of names of countries in the continent or ocean. - countries=`$AWK \ + case $continent in + time) + old_minute=`date -u +%Y%m%d%H%M` + for i in 1 2 3 + do + time_table_command=` + $AWK -v output_times=1 \ + "$output_distances_or_times" <"$TZ_ZONE_TABLE" + ` + time_table=`eval "$time_table_command"` + new_minute=`date -u +%Y%m%d%H%M` + case $old_minute in + "$new_minute") break;; + esac + old_minute=$new_minute + done + echo >&2 'What is the current date and 24-hour time?' + eval doselect ` + say "$time_table" | + sort -k2n -k2,5 -k1n | + $AWK '{ + line = $6 " " $7 " " $4 " " $5 + if (line == oldline) next + oldline = line + gsub(/'\''/, "&\\\\&&", line) + printf "'\''%s'\''\n", line + }' + ` + time=$select_result + zone_table=` + say "$time_table" | + $AWK -v time="$time" '{ + if ($6 " " $7 " " $4 " " $5 == time) { + sub(/[^\t]*\t/, "") + print + } + }' + ` + countries=` + say "$zone_table" | + $AWK \ + -v continent_re='' \ + -v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \ + "$output_country_list" | + sort -f + ` + ;; + *) + zone_table=file + # Get list of names of countries in the continent or ocean. + countries=`$AWK \ -v continent_re="^$continent/" \ -v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \ "$output_country_list" \ <"$TZ_ZONE_TABLE" | sort -f - ` + `;; + esac # If there's more than one country, ask the user which one. case $countries in @@ -493,10 +554,15 @@ while # Get list of timezones in the country. - regions=`$AWK \ + regions=` + case $zone_table in + file) cat -- "$TZ_ZONE_TABLE";; + *) say "$zone_table";; + esac | + $AWK \ -v country="$country" \ -v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \ - ' + ' BEGIN { FS = "\t" cc = country @@ -509,7 +575,8 @@ while } /^#/ { next } $1 ~ cc { print $4 } - ' <"$TZ_ZONE_TABLE"` + ' + ` # If there's more than one region, ask the user which one. @@ -521,11 +588,16 @@ while esac # Determine TZ from country and region. - TZ=`$AWK \ + TZ=` + case $zone_table in + file) cat -- "$TZ_ZONE_TABLE";; + *) say "$zone_table";; + esac | + $AWK \ -v country="$country" \ -v region="$region" \ -v TZ_COUNTRY_TABLE="$TZ_COUNTRY_TABLE" \ - ' + ' BEGIN { FS = "\t" cc = country @@ -538,7 +610,8 @@ while } /^#/ { next } $1 ~ cc && ($4 == region || !region) { print $3 } - ' <"$TZ_ZONE_TABLE"` + ' + `;; esac # Make sure the corresponding zoneinfo file exists. @@ -574,17 +647,20 @@ Universal Time is now: $UTdate." # Output TZ info and ask the user to confirm. echo >&2 "" - echo >&2 "The following information has been given:" + echo >&2 "Based on the following information:" 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";; + case $time%$country%$region%$coord in + ?*%?*%?*%) + say >&2 " $time$newline $country$newline $region";; + ?*%?*%%) say >&2 " $time$newline $country";; + %?*%?*%) 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 "TZ='$TZ' will be used.$extra_info" say >&2 "Is the above information OK?" doselect Yes No -- 2.39.0