【Linux学习】jq：一款json格式化神器

什么是jq？jq是Linux下面把文本字符串格式化成json格式的工具

系统环境：centos 7

一、安装

（1）yum安装

a、安装epel源

# wget http://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm

# rpm -ivh epel-release-latest-7.noarch.rpm

# yum repolist   ###检查是否已经添加到源列表

b、yum install -y jq

（2）源码安装

a、下载源码包

#  wget https://github.com/stedolan/jq/releases/download/jq-1.5/jq-1.5.tar.gz

#  tar zxvf jq-1.5.tar.gz

#  cd jq-1.5

#  ./configure

#  make && make install

编译安装完成以后就能在该目录下看见jq二进制文件了，添加到环境变量~/.bashrc

如图：

# source ~/.bashrc    

安装完成，现在就可以使用jq命令

二、jq测试

（1）简单测试

#  echo '{"yjt":"boy","age":20}' |jq .   #注意，命令最后有一个点，代表显示全部的json文件

效果：

注意：jq命令会检查json格式的合法性，如果不合法，将保错，具体的json格式，请浏览：http://www.w3school.com.cn/json/json_syntax.asp 或者 https://stedolan.github.io/jq/manual/

 （2）通过key获取值，如何获取呢？  

jq '.key'

file文件内容

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71

{ "System_Time":"2018-11-27 17:42:02", "Hostname":"test.com", "Network":[ { "Network_Card": "bond1", "ip":"10.126.140.16", "Input_Traffic": "4.448K/S", "Output_Traffic": "2.649K/S " },{ "Network_Card": "eth4", "ip":null, "Input_Traffic": "2.679K/S", "Output_Traffic": "1.805K/S " },{ "Network_Card": "eth6", "ip":null, "Input_Traffic": "0.750K/S", "Output_Traffic": "0.000K/S " }], "CPU":{ "us":"0%", "sy":"0%", "id":"100%", "wa":"0%", "cpu_rate":"0.01%", "CPU_Load_Average": " 0.15, 0.04, 0.01", "Running_Process":"1", "Total_Process":"696", "Host_Running_Time":" 18 days 22:53", "User_Connection_Number":"2" , "CPU_Status":"Normal" }, "Memory":{ "total_mem":"128644M", "use_mem": "1373M", "free_mem": "127270M", "use_rate": "1%", "free_swap": "65535M", "total_swap": "65535M", "use_swap": "0M", "swap_use_rate": "0%", "Memory_Status":"Normal", "Swap_Memory_Status":"Normal" }, "disk":{ "root_use":"1%", "root_status":"Normal", "var_use":"1%", "vae_status":"Normal", "data_use":"1%", "data_status":"Normal", "data1_use":"0%", "data1_status":"Normal", "data2_use":"1%", "data2_status":"Normal", "data3_use":"1%", "data3_status":"Normal" }, "TCP":{ "TIME_WAIT":"36", "FIN_WAIT1":"0", "FIN_WAIT2":"0", "CLOSE_WAIT":"0", "ESTABLISHED":"2", "SYN_RECV":"0", "LAST_ACKV":"0", "CLOSING":"0" }, "type":"END" }

　　

例：

（3）获取不存在的key会返回null

（4）嵌套解析

（5）内建函数

a、has  用来判断是否存在某个key

b、key  用来获取json中的key元素的

例：