unitproc/bkt-dateDuration

   1 #!/bin/bash
   2
   3 yell() { echo "$0: $*" >&2; } # print script path and all args to stderr
   4 die() { yell "$*"; exit 111; } # same as yell() but non-zero exit status
   5 must() { "$@" || die "cannot $*"; } # runs args as command, reports args if command fails
   6 dateDuration() {
   7     # Desc: Given two date strings, output seconds duration
   8     # Example: dateDuration 2012-06-30 2012-07-01  # Yields 86401 because leap second
   9     # Version 0.0.4
  10     # Depends: GNU Coreutils 9.4 (date, sed), GNU Bash 5.2.21
  11     # References: [1] “Understanding the "right" time zone database” https://kenta.blogspot.com/2016/03/sqfzcxay-understanding-right-time-zone.html
  12
  13     local date1 date2 re unixEpoch1 unixEpoch2 duration;
  14
  15     path_tz="/usr/share/zoneinfo/right/UTC";
  16     if [[ ! -f "$path_tz" ]]; then yell "WARNING:Time zone 'right/UTC' file not found at ${path_tz}. Try 'sudo apt install tzdata-legacy'."; fi;
  17     if [[ $# -ne 2 ]]; then die "FATAL:Need two date arguments. Got $#"; fi;
  18     date1="$1";
  19     date2="$2";
  20     # Check args
  21     if [[ -z "$date1" ]]; then die "FATAL:Invalid first date provided:${date1}"; fi;
  22     if [[ -z "$date2" ]]; then die "FATAL:Invalid second date provided:${date2}"; fi;
  23
  24     ## Convert @-specified unix epoch into right unix epoch (rue)
  25     re='^@.*';
  26     if [[ "$date1" =~ $re ]] || [[ "$date2" =~ $re ]]; then
  27         die "FATAL:@-specified unix epoch detected. Why are you using me?";
  28     fi;
  29
  30     # Convert date strings into Unix epoch. # See [1]
  31     unixEpoch1="$(TZ=right/UTC date --date="$date1" +%s)" || die "Problem with $(declare -p date1)";
  32     unixEpoch2="$(TZ=right/UTC date --date="$date2" +%s)" || die "Problem with $(declare -p date2)";
  33
  34     # Calculate duration
  35     duration="$((unixEpoch2 - unixEpoch1))";
  36     duration=${duration#-};
  37
  38     printf "%s\n" "$duration";
  39 };
  40
  41 # Examples
  42 dateDuration 2026-06-30 2026-07-01; # 86400 seconds
  43 dateDuration 2012-06-30 2012-07-01; # 86401 seconds (leap second)
  44 dateDuration 2000-01-01 1999-12-31; # 86400 seconds
  45 dateDuration 2012-06-30T23:59:59+00 2012-06-30T23:59:60; # 1 (leap second)