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 0.0.1
  10     # Depends: GNU Coreutils 9.4 (date, sed), GNU Bash 5.2.21
  11     # References: [1] “"right" tz database (zoneinfo) files and GPS-based NTP” https://www.ucolick.org/~sla/leapsecs/right+gps.html
  12
  13     date1="$1";
  14     date2="$2";
  15     # Check args
  16     if [[ -z "$date1" ]]; then die "FATAL:Invalid first date provided:${date1}"; fi;
  17     if [[ -z "$date2" ]]; then die "FATAL:Invalid second date provided:${date2}"; fi;
  18     if [[ $# -gt 2 ]]; then die "FATAL:Too many arguments."; fi;
  19     ## Convert @-specified unix epoch into right unix epoch (rue)
  20     re='@.*';
  21     if [[ "$date1" =~ $re ]] || [[ "$date2" =~ $re ]]; then
  22         die "FATAL:@-specified unix epoch detected. Why are you using me?";
  23     fi;
  24
  25     # Use right unix epoch to account for leap seconds.
  26     export TZ=right/UTC; # See [1]
  27
  28     # Convert date strings into Unix epoch
  29     unixEpoch1="$(must date --date="$date1" +%s)";
  30     unixEpoch2="$(must date --date="$date2" +%s)";
  31
  32     # Calculate duration
  33     duration="$((unixEpoch2 - unixEpoch1))";
  34     duration="$(sed -e 's/^-//' <<<"$duration"; )";
  35
  36     printf "%s\n" "$duration";
  37 };
  38
  39 # Examples
  40 dateDuration 2026-06-30 2026-07-01; # 86400 seconds
  41 dateDuration 2012-06-30 2012-07-01; # 86401 seconds (leap second)