sed、逗号、美元符号、单引号和双引号 [英] sed, comma, dollar sign, single quote and double quote

问题描述

这个问题很复杂，但是我希望答案会很简单，只是因为我忽略了一些东西.

The question is complex, but I hope the answer will be simple and just because I've overlook something.

我想做的是，我试图使用"sed"命令从文件中获取匹配行之后的所有行.

What I'm trying to do is, I'm trying to use "sed" command to get all lines since a matched line, from a file.

我发现以下命令可用于我的目的:

I figure out the following commands works for my purpose:

sed -n '/\[ ocsp \]/,$p' openssl.cnf

但是，我想将匹配的单词作为变量传入.因此，我需要将报价从单引号更改为双引号.

However, I'd like to have the matching word passed in as a variable. Therefore, I'll need to change the quote from single quote to double quote.

它没有按我预期的那样工作！

It DOES NOT WORK as I expected!

我的理解是，逗号和美元符号告诉sed命令从匹配点打印到文件末尾.我在这里没看到什么好笑的.但是，当我更改为双引号后，会收到如下错误消息:

My understanding is that, the comma and dollar sign tell s the sed command to print from the matched point until the end of file. I didn't see anything funny here. However, after I change to double quote, I get error message like:

sed: -e expression #1, char 19: unexpected `,'

，我尝试将模式匹配到{}符号等后进行转义或放置命令.没有任何效果.

and I tried escape or put the command after matching pattern in to {} sign etc. Nothing works.

请在这里需要一些帮助.

Need some help out here, please.

推荐答案

内部双引号bash将 $ var 扩展为 var 的值.bash内的单引号不会以这种方式解释美元符号.因此，如果您更改引号，则 $ p 会扩展为(可能是)空值并产生错误.只需在最后一个 $ 之前添加单个baskslash.

Inside double quotes bash expands $var to the value of var. Inside single quotes bash doesn't interpret a dollar sign in this way. So if you changed quotes, than $p was expanded to (probably) empty value and yelded an error. Just add single baskslash before last $.

sed -n "/\\[ ocsp \\]/,\$p" openssl.cnf

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