feat(user/bkdatev):Script to print various verbose iso-8601 dates

diff --git a/user/bkdatev b/user/bkdatev
new file mode 100755 (executable)
index 0000000..b888d57
--- /dev/null
+++ b/user/bkdatev
@@ -0,0 +1,299 @@
+#!/usr/bin/env bash
+# Desc: Baltakatei's verbose date command
+# Usage: bkdatev [args]
+# Example: bkdatev --date="2001-09-11T09:02:59-04"
+# Version: 0.0.1
+# Ref/Attrib: [1] "ISO 8601". Wikipedia. https://en.wikipedia.org/wiki/ISO_8601
+#             [2] "Changing the Locale in Wine" https://stackoverflow.com/a/16428951
+#             [3] "Shanghai vs Beijing" https://bugs.launchpad.net/ubuntu/+source/libgweather/+bug/228554
+# Notes:  * Check `ls -R /usr/share/zoneinfo` for time zone names.
+#         * Check `cat /usr/share/i18n/SUPPORTED` for supported locales.
+#         * For list of valid locales, see: https://manpages.ubuntu.com/manpages/bionic/man3/DateTime::Locale::Catalog.3pm.html
+#         * Locations chosen for population, personal signifiance, and spatial coverage.
+
+line_sep() {
+    # Input: var: n_ln
+    local skip_every=4;
+    ((n_ln++));
+    if ! ((n_ln % "$skip_every")); then
+        printf "\n";
+    fi;
+    return 0;
+}; # periodically print separating blank line
+print_dateline() {
+    # Input: var: $id
+    #        var: $fs_1
+    #        var: $fs_2
+    #        var: $fs_3
+    #        args: $@
+    # Output: stdout
+    # Depends: printf, date
+    # Ref/Attrib: * Truncate string in printf https://stackoverflow.com/a/46812677
+    local s_1 s_2 s_3 s_4;
+
+    s_1="$id";
+    s_2="$(date "$@" "$fs_1")";
+    s_3="$(date "$@" "$fs_2")";
+    s_4="$(date "$@" "$fs_3")";
+
+    printf "%-10.10s %-25.25s (%-20.20s) (%s)" "$s_1" "$s_2" "$s_3" "$s_4";
+    printf "\n";
+
+    unset fs_1 fs_2 fs_3 fs_4;
+    }; # print line of dates
+main() {
+    n_ln=0; # for line_sep()
+    
+    # format strings
+    fs_iso8601="+%Y-%m-%dT%H:%M:%S%:::z"; # typical ISO-8601
+    fs_iso8601_etc="+%G-W%V-%u, %Y-%j"; # alternate ISO-8601 dates
+    fs_locale="+%Z; %A; %c"; # locale-specific date strings
+
+    # vars for print_dateline()
+    fs_1="$fs_iso8601";
+    fs_2="$fs_iso8601_etc";
+    fs_3="$fs_locale";
+
+    # UTC (pop. (2021): 7,837,000,000)
+    (
+        export TZ=UTC;
+        id="UTC";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Hawaii
+    (
+        export TZ=US/Hawaii;
+        export LANG="haw-US.UTF8";
+        id="HAWAII";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Los Angeles, USA
+    (
+        export TZ=America/Los_Angeles;
+        export LANG="en_US.UTF-8";
+        id="LOS ANGELES";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Denver, USA (pop. (2021): 711,463)
+    (
+        export TZ=America/Denver;
+        export LANG="en_US.UTF-8";
+        id="DENVER";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Chicago, USA (pop. (2021): 711,463)
+    (
+        export TZ=America/Chicago;
+        export LANG="en_US.UTF-8";
+        id="CHICAGO";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Mexico City, Mexico (pop. (2018): 21,804,515)
+    (
+        export TZ=America/Mexico_City;
+        export LANG="es_MX.UTF8";
+        id="MEXICO CITY";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Panama City, Panama
+    (
+        export TZ=America/Panama;
+        export LANG="es_PA.UTF8";
+        id="PANAMA CITY";
+        print_dateline "$@";
+    ); line_sep;
+
+    # New York, USA (pop. (2018): 20,140,470)
+    (
+        export TZ=America/New_York;
+        export LANG="en_US.UTF-8";
+        id="NEW YORK";
+        print_dateline "$@";
+    ); line_sep;
+
+    # São Paulo, Brazil
+    (
+        export TZ=America/Sao_Paulo;
+        export LANG="pt_BR.UTF8";
+        id="SAO PAULO";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Buenos Aires
+    (
+        export TZ=America/Argentina/Buenos_Aires;
+        export LANG="es_AR.UTF8";
+        id="BUENOS AIRES";
+        print_dateline "$@";
+    ); line_sep;
+
+    # London, England
+    (
+        export TZ=Europe/London;
+        export LANG="en_GB.UTF-8";
+        id="LONDON";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Kinshasa, Africa
+    (
+        export TZ=Africa/Kinshasa;
+        export LANG="ln_CD.UTF8";
+        id="KINSHASA";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Lagos, Africa
+    (
+        export TZ=Africa/Lagos;
+        export LANG="en_NG.UTF8";
+        id="LAGOS";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Paris, France
+    (
+        export TZ=Europe/Paris;
+        export LANG="fr_FR.UTF8";
+        id="PARIS";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Stockholm, Sweden
+    (
+        export TZ=Europe/Stockholm;
+        export LANG="sv_SE.UTF8";
+        id="STOCKHOLM";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Cairo, Egypt
+    (
+        export TZ=Africa/Cairo;
+        export LANG="ar_EG.UTF8";
+        id="CAIRO";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Athens (pop. (2020): 3,526,887)
+    (
+        export TZ=Europe/Athens;
+        export LANG="el_GR.UTF8";
+        id="ATHENS";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Istanbul (pop. (2020): 13,719,061)
+    (
+        export TZ=Asia/Istanbul;
+        export LANG="tr_TR.UTF8";
+        id="ISTANBUL";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Tehran, Iran
+    (
+        export TZ=Asia/Tehran;
+        export LANG="fa_IR.UTF8";
+        id="TEHRAN";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Moscow, Russia
+    (
+        export TZ=Europe/Moscow;
+        export LANG="ru_RU.UTF-8";
+        id="MOSCOW";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Kyiv, Ukraine (pop. (2021): 2,962,180)
+    (
+        export TZ=Europe/Kyiv;
+        export LANG="uk_UA.UTF-8";
+        id="KYIV";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Delhi, India (pop. (2018): 29,000,000)
+    (
+        export TZ=Asia/Kolkata;
+        export LANG="hi_IN.UTF-8";
+        id="DELHI";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Jakarta, Indonesia (pop. (2018): 33,430,285)
+    (
+        export TZ=Asia/Jakarta;
+        export LANG="id_ID.UTF8";
+        id="JAKARTA";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Singapore, Singapore (pop (2018): 5,792,000)
+    (
+        export TZ=Asia/Singapore;
+        export LANG="en_SG.UTF-8";
+        id="SINGAPORE";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Beijing, China (pop. (2018): 19,618,000)
+    (
+        export TZ=Asia/Shanghai; # [3]
+        export LANG="zh_CN.UTF-8";
+        id="BEIJING";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Tokyo, Japan (pop. (2018): 37,274,000)
+    (
+        export TZ=Asia/Tokyo;
+        export LANG="ja_JP.UTF8";
+        id="TOKYO";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Seoul, South Korea (pop. (2018): 25,514,000)
+    (
+        export TZ=Asia/Seoul;
+        export LANG="ko_KR.UTF8";
+        id="SEOUL";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Sydney, Australia
+    (
+        export TZ=Australia/Sydney;
+        export LANG="en_AU.UTF8";
+        id="SYDNEY";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Guam
+    (
+        export TZ=Pacific/Guam;
+        export LANG="en_GU.UTF8";
+        id="GUAM";
+        print_dateline "$@";
+    ); line_sep;
+
+    # Auckland, New Zealand
+    (
+        export TZ=Pacific/Auckland;
+        export LANG="en_NZ.UTF8";
+        id="AUCKLAND";
+        print_dateline "$@";
+    ); line_sep;
+    
+    return 0;
+}; # main program
+
+main "$@";