如何在OS X Leopard上的bash脚本中进行数学约会? [英] How do I do date math in a bash script on OS X Leopard?

问题描述

我意识到我可以启动一个C或Ruby程序来做到这一点，但是我希望我的脚本具有尽可能少的依赖关系.

I realize I could whip up a little C or Ruby program to do this, but I want my script to have as few dependencies as possible.

鉴于 caveat ，如何在OS X上的bash脚本中进行日期数学计算?我在其他网站上看到过一个帖子，其中有人执行了以下操作:

Given that caveat, how does one do date math in a bash script on OS X? I've seen a post (on another site) where someone did the following:

date -d "-1 day"

但这在OS X上似乎不起作用.

But this does not seem to work on OS X.

附录:

好几个人都评论并回答说Ruby，Python，Perl等是OS X的标准配置.我对这三种语言都很熟悉，并且可以轻松编写符合我想要的脚本.实际上，我已经有一个用Ruby编写的脚本.

Several people have commented and responded that Ruby, Python, Perl, and the like come standard with OS X. I'm familiar with all three of these languages and could easily write a script that does what I want. As a matter of fact, I already have such a script, written in Ruby.

所以也许我应该澄清外部依赖"的含义.我的意思是，我不希望我的bash脚本必须调用其外部的任何其他脚本.换句话说，我希望它使用在OS X的原始安装中可用的并且已经在路径中的一些实用程序.

So perhaps I should clarify what I mean by 'external dependency'. What I mean is, I don't want my bash script to have to call any other script external to it. In other words, I want it to use some utility available in a vanilla installation of OS X and already on the path.

但是，看起来这是不可能的，所以我将不得不依靠我的外部依赖项:一个Ruby脚本.

However, it doesn't look like this is possible, so I will have to make due with my external dependency: a Ruby script.

推荐答案

$ date -v -1d

-d设置夏令时标记.

-d sets Daylight Savings time flag.

请尝试约会日期以获取更多信息.

Try man date for more info.

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