如何用awk变量在常规的前pressions？ [英] How to use awk variables in regular expressions?

问题描述

我有一个名为域文件，其中包含某些域。例如：

I have a file called domain which contains some domains. For example:

google.com
facebook.com
...
yahoo.com

和我有另一个名为文件网站其中包含了一些网站的网址和电话号码。例如：

And I have another file called site which contains some sites URLs and numbers. For example:

image.google.com   10
map.google.com     8
...
photo.facebook.com  22
game.facebook.com   15
..

现在我要算的网址数量每个域都有。例如： google.com 的 10 + 8 。所以我写了一个awk脚本是这样的：

Now I'm going to count the url number each domain has. For example: google.com has 10+8. So I wrote an awk script like this:

BEGIN{
  while(getline dom < "./domain" > 0) {
    domain[dom]=0;
  }
  for(dom in domain) {
    while(getline < "./site" > 0) {
      if($1 ~/$dom$)   #if $1 end with $dom {
        domain[dom]+=$2;
      }
    }
  }
}

不过，code 如果（$ 1〜/ $ DOM $）不运行像我想要的。因为在常规的前pression变量$ DOM是从字面上解释。所以，第一个问题是：

But the code if($1 ~/$dom$) doesn't run like I want. Because the variable $dom in the regular expression was explained literally. So, the first question is:

有没有办法使用变量 $ DOM 在常规的前pression？

Is there any way to use variable $dom in a regular expression?

然后，我是新来写剧本

有没有什么更好的办法来解决我的问题？

推荐答案

首先，该变量 DOM 不是 $ DOM - 考虑 $ 作为操作员提取存储在变量中的列数的值 DOM

First of all, the variable is dom not $dom -- consider $ as an operator to extract the value of the column number stored in the variable dom

其次，awk将不会插 // 之间有什么 - 那就是在那里一个字符串

Secondly, awk will not interpolate what's between // -- that is just a string in there.

您想要的匹配（）函数，其中第二个参数可以是被当作常规的前pression的字符串：

You want the match() function where the 2nd argument can be a string that is treated as the regular expression:

if (match($1, dom "$")) {...}

我想code的解决方案，如：

I would code a solution like:

awk '
  FNR == NR {domain[$1] = 0; next}
  {
    for (dom in domain) {
      if (match($1, dom "$")) {
        domain[dom] += $2
        break
      }
    }
  }
  END {for (dom in domain) {print dom, domain[dom]}}
' domain site 

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