如何从终端读取日期并与当前日期进行比较 [英] How to read date from terminal and compare with current date

问题描述

我想知道从终端读取日期并使用shell脚本与当前日期进行比较的适当方式，

I want to know the appropriate way of reading date from terminal and comparing with current date using shell script,

我有以下脚本，

a=`date +%Y-%m-%d`
while [ 1 ] ; do
        echo "Enter Date"
    read todate
    if [ $todate < $a ];then
        break;
    fi
    echo "todate greater than curDate" 
done 

它没有按预期运行。

更新

这是我的最终版本，

Here is my final version,

#! /bin/bash
DATE=$(date '+%s')
while [ 1 ] ; do
        echo "Enter Date[DD MM YYYY]:"    
    read D M Y
    THIS=$(date -d "$Y-$M-$D" '+%s')

    if (( THIS < DATE )) ; then
        break
    fi
done

谢谢大家！

推荐答案

来自高级Bash脚本编写指南：

7.3。其他比较运算符

7.3. Other Comparison Operators

...

字符串比较

...

<
    is less than, in ASCII alphabetical order

    if [[ "$a" < "$b" ]]

    if [ "$a" \< "$b" ]

    Note that the "<" needs to be escaped within a [ ] construct.

所以，您的

   if [ $todate < $a ];then

成为

if [ $todate \< $a ];then

或

if [[ $todate < $a ]];then

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