bash-如何获取(当前)朱利安天数? [英] bash - how to get (current) Julian day number?

问题描述

如何获取今天的 Julian天数(JDN)等效?还是任何日期?

How to get today's Julian day number (JDN) equivalent? or any date's, for that matter?

我看了看，但只发现了一些产生"year-dayOfYear"的函数，而不是2457854.

I've looked and looked, but only found some functions that produced "year-dayOfYear", not something like: 2457854.

推荐答案

我最终自己移植了一个.这是 SSCCE :

I ended up porting one myself. Here is a SSCCE:

#!/bin/bash

function GetJulianDay # year, month, day
{
  year=$1
  month=$2
  day=$3

  jd=$((day - 32075 + 1461 * (year + 4800 - (14 - month) / 12) / 4 + 367 * (month - 2 + ((14 - month) / 12) * 12) / 12 - 3 * ((year + 4900 - (14 - month) / 12) / 100) / 4))

  echo $jd
}

function GetTodayJulianDay
{
  year=`date +"%Y"`
  month=`date +"%m"`
  day=`date +"%d"`

  todayJd=$(GetJulianDay $year $month $day)

  echo $todayJd
}

# samples

todayJd=$(GetTodayJulianDay)
echo "got today jd: $todayJd"

yesterdayJd=$(GetJulianDay 2017 4 9)
echo "got yesterday jd: $yesterdayJd"

对其进行测试: http://aa.usno.navy.mil/data/docs/JulianDate.php

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