计算 Unix 中两个日期之间的月差？

Question

我有两个格式为 'YYYYMM'

的变量

DATE1=201712
DATE2=201801

如何在 unix 中计算这两个日期变量之间的月差？

Answer 1

怎么样：

#!/bin/bash

DATE1=201712
DATE2=201801

y1=${DATE1:0:4}
m1=${DATE1:4:2}

y2=${DATE2:0:4}
m2=${DATE2:4:2}

diff=$(( ($y2 - $y1) * 12 + (10#$m2 - 10#$m1) ))
echo $diff

Answer 2

我准备了下面的bash函数给大家看清楚了告诉我:

#!/usr/bin/env bash

DATE1=201712
DATE2=201801

function dateDiffMonth() {
    local y1=$(date -d """01" '+%Y') # extract the year from your date1
    local y2=$(date -d """01" '+%Y') # extract the year from your date2
    local m1=$(date -d """01" '+%m') # extract the month from your date1
    local m2=$(date -d """01" '+%m') # extract the month from your date2
    echo $(( ($y2 - $y1) * 12 + (10#$m2 - 10#$m1) )) #compute the months difference 12*year diff+ months diff -> 10# force the shell to interpret the following number in base-10
}

RESULT=`dateDiffMonth $DATE1 $DATE2`
echo "there is a gap of $RESULT months betwen $DATE2 and $DATE1"

计算 Unix 中两个日期之间的月差？

Calculate difference in months between two dates in Unix?

unix

bash

shell

sh

unix-timestamp