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jq知识解答

leader 2021年05月25日 程序员 148 0
1. 简介
json是一种轻量级的数据交换格式,应用范围非常广泛。在Linux系统下使用jq工具可以非常方便的处理json,官方给的定义是:
 
A jq program is a “filter”: it takes an input, and produces an output. There are a lot of builtin filters for extracting a particular field of an object, or converting a number to a string, or various other standard tasks.
 
通俗的说就是一个能够接受json,处理json,输出json的程序,反正很好用。
安装起来也非常的方便,直接使用yum即可安装。
[root@test-dhcp ~]# yum install jq
 
2. 基本操作
2.1 创建
[root@test-dhcp ~]# jq -n {a:1} { "a": 1 } 
[root@test-dhcp ~]# jq -n '{a:"test"}' { "a": "test" }
 
2.2 合并
[root@test-dhcp ~]# jq -n '{a:"test"} + {b:2}' { "a": "test", "b": 2 } 
[root@test-dhcp ~]# jq -n '{a:"test"} + {b:2} + {c:"testc"}' { "a": "test", "b": 2, "c": "testc" }
 
2.3 删除
[root@test-dhcp ~]# cat test.json {"a": "test","b": 2, "c": "testc"} 
[root@test-dhcp ~]# cat test.json |jq . { "a": "test", "b": 2, "c": "testc" }
[root@test-dhcp ~]# cat test.json |jq 'del(.b)' { "a": "test", "c": "testc" }
 
2.4 更新
[root@test-dhcp ~]# cat test.json {"a": "test","b": 2, "c": "testc"} 
[root@test-dhcp ~]# cat test.json |jq '.b="testb"' { "a": "test", "b": "testb", "c": "testc" }
[root@test-dhcp ~]# cat test.json |jq '. + {d:4}' { "a": "test", "b": 2, "c": "testc", "d": 4 } [
root@test-dhcp ~]# cat test.json |jq '. + {d:4}' |jq '.d={dd:5}' { "a": "test", "b": 2, "c": "testc", "d": { "dd": 5 } }
 
2.5 查询
[root@test-dhcp ~]# cat test.json |jq . { "a": "test", "b": 2, "c": "testc", "d": { "dd": 5 } } 
[root@test-dhcp ~]# cat test.json |jq '. + {d:4}' |jq '.d={dd:5}' |jq .d.dd 5 [root@test-dhcp ~]# echo '{"a":1,"b":2}' |jq '[.a,.b]' [ 1, 2 ]
 
2.6 查看数据类型
[root@test-dhcp ~]# echo "{}" |jq -r type object 
[root@test-dhcp ~]# echo '[0, false, [], {}, null, "hello"]' |jq 'map(type)' [ "number", "boolean", "array", "object", "null", "string" ]
 
2.7 查询数组中的值
[root@test-dhcp ~]# echo [1,2,3] |jq .[1] 2 
[root@test-dhcp ~]# echo [1,2,3] |jq .[2] 3 查询数组长度
[root@test-dhcp ~]# echo [1,2,3,9] |jq '.|length' 4
[root@test-dhcp ~]# echo [1,2,3] |jq '.|length' 3
 
2.8 数组相加
[root@test-dhcp ~]# echo [1,2,3] |jq '. + [4,5,6]' [ 1, 2, 3, 4, 5, 6 ]
 
2.9 高级查询
[root@test-dhcp ~]# echo [1,2,3] | jq 'map(select(. >= 2))' [ 2, 3 ] 
[root@test-dhcp ~]# echo [1,2,3] | jq 'map(select(. == 2))' [ 2 ]
[root@test-dhcp ~]# echo [1,2,3] | jq 'map(select(. != 2))' [ 1, 3 ]
[root@test-dhcp ~]# cat test.json [ { "id": "0", "model": "Intel(R)Xeon(R)CPUE5-2620v4@2.10GHz" }, { "id": "1", "model": "Intel(R)Xeon(R)CPUE5-2620v4@2.10GHz" } ]
[root@test-dhcp ~]# cat test.json |jq .[].model "Intel(R)Xeon(R)CPUE5-2620v4@2.10GHz" "Intel(R)Xeon(R)CPUE5-2620v4@2.10GHz"
 
2.10 类型转换
[root@test-dhcp ~]# echo '["a","b,c,d","e"]' |jq 'join(",")' "a,b,c,d,e" 
[root@test-dhcp ~]# echo '["a","b,c,d","e",1]' |jq 'join(",")' jq: error (at <stdin>:1): string (",") and number (1) cannot be added
[root@test-dhcp ~]# cat test.json liuxin,30,male jiaweiqiang,29,femal
[root@test-dhcp ~]# jq -R 'split(",")|{"name":.[0],"age":.[1],"sex":.[2]}' ./test.json { "name": "liuxin", "age": "30", "sex": "male" } { "name": "jiaweiqiang", "age": "29", "sex": "femal" }
[root@test-dhcp ~]# cat test.json { "name": "liuxin", "age": "30", "sex": "male" } { "name": "jiaweiqiang", "age": "29", "sex": "femal" }
[root@test-dhcp ~]# cat test.json |jq . -c {"name":"liuxin","age":"30","sex":"male"} {"name":"jiaweiqiang","age":"29","sex":"femal"}
 
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