[Linux] jq：命令行JSON处理工具

jq命令帮助我们很方便地在终端查看和处理json文件

jq命令的帮助信息：

abby@abby:bgs$ jq -h
jq - commandline JSON processor [version 1.5-1-a5b5cbe]
Usage: jq [options] <jq filter> [file...]

    jq is a tool for processing JSON inputs, applying the
    given filter to its JSON text inputs and producing the
    filter's results as JSON on standard output.
    The simplest filter is ., which is the identity filter,
    copying jq's input to its output unmodified (except for
    formatting).
    For more advanced filters see the jq(1) manpage ("man jq")
    and/or https://stedolan.github.io/jq

    Some of the options include:
     -c        compact instead of pretty-printed output;
     -n        use `null` as the single input value;
     -e        set the exit status code based on the output;
     -s        read (slurp) all inputs into an array; apply filter to it;
     -r        output raw strings, not JSON texts;
     -R        read raw strings, not JSON texts;
     -C        colorize JSON;
     -M        monochrome (don't colorize JSON);
     -S        sort keys of objects on output;
     --tab    use tabs for indentation;
     --arg a v    set variable $a to value <v>;
     --argjson a v    set variable $a to JSON value <v>;
     --slurpfile a f    set variable $a to an array of JSON texts read from <f>;
    See the manpage for more options.

#默认情况下，jq会将json格式化为多行树状结构输出，但有时需要将一个json串在一行输出，可使用-c参数，例如

jq -c . xxx.json 

#用逗号分隔可以同时获取json中多个key的值。但过滤出的多个值会分多行显示。要注意除了逗号之外不能有其他字符（包括空格），例如

js .field1,.field2 xxx.json

使用：

$ jq . xxx.json   # 直接将文件名传给 jq
$ cat bgs_enterprise_info_norm.json | jq .  #或者由其他命令读出文件内容，并传给 jq

例子：

原始数据：

abby@abby:bgs$ head -n2 bgs_enterprise_info_norm.json
{"industry": "纺织服装、服饰业", "name": "xxx公司", "business": "xxxxx", "description": "空值"}
{"industry": "批发业", "name": "xxx公司", "business": "xxxxx", "description": "空值"}

格式化：

abby@abby:bgs$ head -n2 bgs_enterprise_info_norm.json | jq .
{
  "industry": "纺织服装、服饰业",
  "name": "xxx公司",
  "business": "xxxxx",
  "description": "空值"
}
{
  "industry": "批发业",
  "name": "xxx公司",
  "business": "xxxxx",
  "description": "空值"
}

选取某属性：

abby@abby:bgs$ head -n2 bgs_enterprise_info_norm.json | jq .industry
"纺织服装、服饰业"
"批发业"

abby@abby:bgs$ jq .description bgs_enterprise_info_norm.json | grep 空值 | wc -l
2770786

内建函数
jq还有一些内建函数如 key，has
key是用来获取JSON中的key元素的：

cat json_raw.txt | jq 'keys'
[
  "employees",
  "location",
  "name"
]

has是用来是判断是否存在某个key： 

cat json_raw.txt | jq 'has("name")'
true

cat json_raw.txt | jq 'has("noexisted")'
false

参考：

linux 命令之jq

jq : Linux下json的命令行工具

命令行 JSON 处理工具 jq 的使用介绍

 jq : Linux下json的命令行工具-Bean_lee-ChinaUnix博客