如何创建一个用户环境变量，每次调用时会调用*％日期％或％时间％？ [英] How to create a user Environment variable that *calls* %date% or %time% each time it's invoked?

问题描述

我试图用以下定义创建2个用户环境变量：

I'm trying to create 2 user environment variables with the following defintion:

datel=%date:~-4%%date:~3,2%%date:~0,2%
datetime=%date:~-4%%date:~3,2%%date:~0,2%-%time:~0,2%_%time:~3,2%_%time:~6,2%

，以便每次我打电话：

echo %datel%
echo %datetime%

我得到：

20110407
20110407-11_45_45

我可以在GUI中定义用户环境变量，没有问题（计算机 - >（右键单击）属性 - >高级系统设置 - >环境变量），当我在新的cmd窗口中进行设置时，我得到以下内容：

I can define the user environment variables without problems in the GUI (Computer->(Right Click)Properties->Advanced System Settings->Environment Variables) and when I do a "set" in a new cmd window I get the following:

>set da  
datel=%date:~-4%%date:~3,2%%date:~0,2%
datetime=%date:~-4%%date:~3,2%%date:~0,2%-%time:~0,2%_%time:~3,2%_%time:~6,2%

但是，回音他们不是我预期的：

But then "echoing" them is not what I expected:

C:\Users\jaravj
>echo %datel%
%date:~-4%%date:~3,2%%date:~0,2%

C:\Users\jaravj
>echo %datetime%
%date:~-4%%date:~3,2%%date:~0,2%-%time:~0,2%_%time:~3,2%_%time:~6,2%

谢谢或者使用延迟扩展，那么您可以在一行中扩展两次。

Thanks a huge lot in advance.

推荐答案

p>

Or use the delayed expansion, then you are able to expands two times in one line.

setlocal
set "datel=!date:~-4!!date:~3,2!!date:~0,2!"
setlocal EnableDelayedExpansion
echo %datel%

它的作品是因为，首先批处理日期：〜4！日期：〜3,2！日期：〜0,2！ c $ c> / code>，所有百分比扩展完成后。

It's works because, first the batch line parser expands %datel% to !date:~-4!!date:~3,2!!date:~0,2! and after all percent expansions are done.

然后转义字符被处理，然后作为最后一个阶段，解析器扩展感叹号将被扩展。

Then the escape characters are handled, and then as the last phase the parser expands the exclamations are expanded.

在如何解析cmd.exe中解释脚本

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