shell日期格式和数字运算

#!/bin/bash

#declare d="2016-05-06 00:00:00"
#d1=$(date -d "$d" +%s);
#echo $d1
#d2=$(date +%Y%m%d%H%M%S -d @$d1)
#echo $d2

#当前时间 年月日时分秒
#declare currentSecond=$(date +%Y%m%d%H%M%S)
#当前时间 年月日时分
#declare currentMinute=$(date +%Y%m%d%H%M)
#当前时间 年月日时
#declare currentHour=$(date +%Y%m%d%H)
#当前时间 年月日
#declare currentDay=$(date +%Y%m%d)

declare currentHourOfSecond=$(date +%s)
declare currentHour=$(date +%Y%m%d%H -d @$currentHourOfSecond)
#[做运算时，运算符要和前后变量添加空格]
declare beforeOneHourOfSecond=`expr $currentHourOfSecond - 3600`
declare beforeOneHour=$(date +%Y%m%d%H -d @$beforeOneHourOfSecond)
declare beforeTwoHourOfSecond=`expr $currentHourOfSecond - 7200`
declare beforeTwoHour=$(date +%Y%m%d%H -d @$beforeTwoHourOfSecond)
echo "beforeOneHour:"$beforeOneHour
echo "beforeTwoHour:"$beforeTwoHour

#获取前一个小时时间
#declare beforeOneHour=$(date +%Y%m%d%H -d ‘-1 hours‘)
#获取前两个小时时间
#declare beforeTwoHour=$(date +%Y%m%d%H -d ‘-2 hours‘)

#echo "currentSecond:"$currentSecond
#echo "currentMinute:"$currentMinute
#echo "currentHour:"$currentHour
#echo "currentDay:"$currentDay
#echo "beforeOneHour:"$beforeOneHour
#echo "beforeTwoHour:"$beforeTwoHour