我试图解析从curl请求返回的JSON,就像这样:

curl 'http://twitter.com/users/username.json' |
    sed -e 's/[{}]/''/g' | 
    awk -v k="text" '{n=split($0,a,","); for (i=1; i<=n; i++) print a[i]}'

上面将JSON划分为多个字段,例如:

% ...
"geo_enabled":false
"friends_count":245
"profile_text_color":"000000"
"status":"in_reply_to_screen_name":null
"source":"web"
"truncated":false
"text":"My status"
"favorited":false
% ...

我如何打印一个特定的字段(由-v k=文本表示)?


当前回答

对于更复杂的JSON解析,我建议使用Python jsonpath模块(Stefan Goessner) -

Install it - sudo easy_install -U jsonpath Use it - Example file.json (from http://goessner.net/articles/JsonPath) - { "store": { "book": [ { "category": "reference", "author": "Nigel Rees", "title": "Sayings of the Century", "price": 8.95 }, { "category": "fiction", "author": "Evelyn Waugh", "title": "Sword of Honour", "price": 12.99 }, { "category": "fiction", "author": "Herman Melville", "title": "Moby Dick", "isbn": "0-553-21311-3", "price": 8.99 }, { "category": "fiction", "author": "J. R. R. Tolkien", "title": "The Lord of the Rings", "isbn": "0-395-19395-8", "price": 22.99 } ], "bicycle": { "color": "red", "price": 19.95 } } } Parse it (extract all book titles with price < 10) - cat file.json | python -c "import sys, json, jsonpath; print '\n'.join(jsonpath.jsonpath(json.load(sys.stdin), 'store.book[?(@.price < 10)].title'))" Will output - Sayings of the Century Moby Dick Note: The above command line does not include error checking. For a full solution with error checking, you should create a small Python script, and wrap the code with try-except.

其他回答

更新(2020)

我使用外部工具(例如Python)时遇到的最大问题是,你必须处理包管理器和安装它们的依赖关系。

然而,现在我们有了jq作为一个独立的静态工具,很容易通过GitHub发布和Webi (webinstall.dev/jq)跨平台安装,我建议:

Mac、Linux:

curl -sS https://webi.sh/jq | bash

Windows 10:

curl.exe -A MS https://webi.ms/jq | powershell

小抄:https://webinstall.dev/jq

原(2011)

TickTick是一个用bash编写的JSON解析器(不到250行代码)。

以下是作者在他的文章《想象一个Bash支持JSON的世界》中的片段:

#!/bin/bash
. ticktick.sh

``
  people = {
    "Writers": [
      "Rod Serling",
      "Charles Beaumont",
      "Richard Matheson"
    ],
    "Cast": {
      "Rod Serling": { "Episodes": 156 },
      "Martin Landau": { "Episodes": 2 },
      "William Shatner": { "Episodes": 2 }
    }
  }
``

function printDirectors() {
  echo "  The ``people.Directors.length()`` Directors are:"

  for director in ``people.Directors.items()``; do
    printf "    - %s\n" ${!director}
  done
}

`` people.Directors = [ "John Brahm", "Douglas Heyes" ] ``
printDirectors

newDirector="Lamont Johnson"
`` people.Directors.push($newDirector) ``
printDirectors

echo "Shifted: "``people.Directors.shift()``
printDirectors

echo "Popped: "``people.Directors.pop()``
printDirectors

基于这里的一些建议(特别是在评论中)建议使用Python,我很失望没有找到一个例子。

下面是一行程序,从JSON数据中获取单个值。它假设您将数据输送进来(从某个地方),因此在脚本上下文中应该很有用。

echo '{"hostname":"test","domainname":"example.com"}' | python -c 'import json,sys;obj=json.load(sys.stdin);print obj["hostname"]'

如果有人只想从简单的JSON对象中提取值,而不需要嵌套结构,那么甚至不需要离开Bash就可以使用正则表达式。

下面是我使用基于JSON标准的bash正则表达式定义的函数:

function json_extract() {
  local key=$1
  local json=$2

  local string_regex='"([^"\]|\\.)*"'
  local number_regex='-?(0|[1-9][0-9]*)(\.[0-9]+)?([eE][+-]?[0-9]+)?'
  local value_regex="${string_regex}|${number_regex}|true|false|null"
  local pair_regex="\"${key}\"[[:space:]]*:[[:space:]]*(${value_regex})"

  if [[ ${json} =~ ${pair_regex} ]]; then
    echo $(sed 's/^"\|"$//g' <<< "${BASH_REMATCH[1]}")
  else
    return 1
  fi
}

注意:对象和数组不支持作为值,但支持标准中定义的所有其他值类型。另外,只要具有完全相同的键名,无论对在JSON文档中有多深,都将匹配。

以OP为例:

$ json_extract text "$(curl 'http://twitter.com/users/username.json')"
My status

$ json_extract friends_count "$(curl 'http://twitter.com/users/username.json')"
245

如果pip在系统中可用,则:

$ pip install json-query

用法示例:

$ curl -s http://0/file.json | json-query
{
    "key":"value"    
}

$ curl -s http://0/file.json | json-query my.key
value

$ curl -s http://0/file.json | json-query my.keys.
key_1
key_2
key_3

$ curl -s http://0/file.json | json-query my.keys.2
value_2

你可以使用jshon:

curl 'http://twitter.com/users/username.json' | jshon -e text