从JSON查找键的值 [英] Find the value of key from JSON

问题描述

我想从这行JSON中提取"id"键.

I'd like to extract the "id" key from this single line of JSON.

我相信这可以使用grep来完成，但是我不确定正确的方法.

I believe this can be accomplished with grep, but I am not sure on the correct way.

如果有一种更好的方法没有依赖项，我会很感兴趣.

If there is a better way that does not have dependencies, I would be interested.

这是我的示例输出:

{"data": {"name": "test", "id": "4dCYd4W9i6gHQHvd", "domains": ["www.test.domain.com", "test.domain.com"], "serverid": "bbBdbbHF8PajW221", "ssl": null, "runtime": "php5.6", "sysuserid": "4gm4K3lUerbSPfxz", "datecreated": 1474597357}, "actionid": "WXVAAHQDCSILMYTV"}

推荐答案

如果您有可以执行Perl兼容正则表达式(PCRE)的grep:

If you have a grep that can do Perl compatible regular expressions (PCRE):

$ grep -Po '"id": *\K"[^"]*"' infile.json
"4dCYd4W9i6gHQHvd"

• -P启用PCRE
• -o只保留匹配项
• "id": *匹配"id"和任意数量的空格
• \K将所有内容都扔掉了(可变大小正向后看")
• "[^"]*"匹配两个引号以及它们之间的所有非引号
• -P enables PCRE
• -o retains nothing but the match
• "id": * matches "id" and an arbitrary amount of spaces
• \K throws away everything to its left ("variable size positive look-behind")
• "[^"]*" matches two quotes and all the non-quotes between them

如果您的grep无法做到这一点，那么您就可以使用

If your grep can't do that, you an use

$ grep -o '"id": *"[^"]*"' infile.json | grep -o '"[^"]*"$'
"4dCYd4W9i6gHQHvd"

这两次使用grep.第一个命令的结果为"id": "4dCYd4W9i6gHQHvd";第二个命令删除除一对引号和它们之间的非引号之外的所有内容，这些引号停在字符串($)的末尾.

This uses grep twice. The result of the first command is "id": "4dCYd4W9i6gHQHvd"; the second command removes everything but a pair of quotes and the non-quotes between them, anchored at the end of the string ($).

但是，正如所指出的那样，您不应为此使用grep，而应使用可以解析JSON的工具.例如 jq :

But, as pointed out, you shouldn't use grep for this, but a tool that can parse JSON – for example jq:

$ jq '.data.id' infile.json
"4dCYd4W9i6gHQHvd"

这只是data对象中id键的简单过滤器.要消除双引号，可以使用-r(原始输出")选项:

This is just a simple filter for the id key in the data object. To get rid of the double quotes, you can use the -r ("raw output") option:

$ jq -r '.data.id' infile.json
4dCYd4W9i6gHQHvd

jq还可以整齐地打印您的JSON:

jq can also neatly pretty print your JSON:

$ jq . infile.json
{
  "data": {
    "name": "test",
    "id": "4dCYd4W9i6gHQHvd",
    "domains": [
      "www.test.domain.com",
      "test.domain.com"
    ],
    "serverid": "bbBdbbHF8PajW221",
    "ssl": null,
    "runtime": "php5.6",
    "sysuserid": "4gm4K3lUerbSPfxz",
    "datecreated": 1474597357
  },
  "actionid": "WXVAAHQDCSILMYTV"
}

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