shell脚本如何方便地处理JSON格式的数据呢，这里介绍一个工具：jq
使用参数介绍：https://stedolan.github.io/jq/manual/
官方教程简单翻译如下。
1、获取JSON数据
我们以github上jq项目最新5条评论的JSON数据为例。获取数据如下:
curl 'https://api.github.com/repos/stedolan/jq/commits?per_page=5'
结果如下：
[
{
"sha": "d25341478381063d1c76e81b3a52e0592a7c997f",
"commit": {
"author": {
"name": "Stephen Dolan",
"email": "mu@netsoc.tcd.ie",
"date": "2013-06-22T16:30:59Z"
},
"committer": {
"name": "Stephen Dolan",
"email": "mu@netsoc.tcd.ie",
"date": "2013-06-22T16:30:59Z"
},
"message": "Merge pull request #162 from stedolan/utf8-fixes
Utf8 fixes. Closes #161",
"tree": {
"sha": "6ab697a8dfb5a96e124666bf6d6213822599fb40",
"url": "https://api.github.com/repos/stedolan/jq/git/trees/6ab697a8dfb5a96e124666bf6d6213822599fb40"
},
"url": "https://api.github.com/repos/stedolan/jq/git/commits/d25341478381063d1c76e81b3a52e0592a7c997f",
"comment_count": 0
},
"url": "https://api.github.com/repos/stedolan/jq/commits/d25341478381063d1c76e81b3a52e0592a7c997f",
"html_url": "https://github.com/stedolan/jq/commit/d25341478381063d1c76e81b3a52e0592a7c997f",
"comments_url": "https://api.github.com/repos/stedolan/jq/commits/d25341478381063d1c76e81b3a52e0592a7c997f/comments",
"author": {
"login": "stedolan",
...
2、高亮并按属性排序显示
用 jq '.'即可：
curl 'https://api.github.com/repos/stedolan/jq/commits?per_page=5' | jq '.'
结果：
[
{
"parents": [
{
"html_url": "https://github.com/stedolan/jq/commit/54b9c9bdb225af5d886466d72f47eafc51acb4f7",
"url": "https://api.github.com/repos/stedolan/jq/commits/54b9c9bdb225af5d886466d72f47eafc51acb4f7",
"sha": "54b9c9bdb225af5d886466d72f47eafc51acb4f7"
},
{
"html_url": "https://github.com/stedolan/jq/commit/8b1b503609c161fea4b003a7179b3fbb2dd4345a",
"url": "https://api.github.com/repos/stedolan/jq/commits/8b1b503609c161fea4b003a7179b3fbb2dd4345a",
"sha": "8b1b503609c161fea4b003a7179b3fbb2dd4345a"
}
],
"committer": {
"type": "User",
"received_events_url": "https://api.github.com/users/stedolan/received_events",
"events_url": "https://api.github.com/users/stedolan/events{/privacy}",
"repos_url": "https://api.github.com/users/stedolan/repos",
"organizations_url": "https://api.github.com/users/stedolan/orgs",
...
这里的评论内容比较多，我们现在想拿第一个评论。
3、获取数组某一项
curl 'https://api.github.com/repos/stedolan/jq/commits?per_page=5' | jq '.[0]'
结果：
View Code可以看到，我们已经拿到了一条完整的评论内容。但我们真正关心的只是评论内容和用户名，下面来获取这两项内容。
4、自定义格式输出某一项
jq '.[0] | {message: .commit.message, name: .commit.committer.name}'
结果：
{
"name": "Stephen Dolan",
"message": "Merge pull request #162 from stedolan/utf8-fixes
Utf8 fixes. Closes #161"
}
我们可以看到，已经拿到了想要的内容，并且已经按我们自己定义的格式显示了。
这里 | 后面的内容是以前面的内容为输入的，.commit 中的 . 就是指 .[0] 中的内容。
5、自定义格式输出多项
jq '.[] | {message: .commit.message, name: .commit.committer.name}'
结果：
{
"name": "Stephen Dolan",
"message": "Merge pull request #162 from stedolan/utf8-fixes
Utf8 fixes. Closes #161"
}
{
"name": "Stephen Dolan",
"message": "Reject all overlong UTF8 sequences."
}
{
"name": "Stephen Dolan",
"message": "Fix various UTF8 parsing bugs.
In particular, parse bad UTF8 by replacing the broken bits with U+FFFD
and resychronise correctly after broken sequences."
}
{
"name": "Stephen Dolan",
"message": "Fix example in manual for `floor`. See #155."
}
{
"name": "Nicolas Williams",
"message": "Document floor"
}
这里 .[] 获取的是数组中的所有项。
我们看到，结果是一个个独立的JSON对象，如何把结果组合成一个数组呢？
6、以数组形式自定义输出多项
jq '[.[] | {message: .commit.message, name: .commit.committer.name}]'
结果：
[
{
"name": "Stephen Dolan",
"message": "Merge pull request #162 from stedolan/utf8-fixes
Utf8 fixes. Closes #161"
},
{
"name": "Stephen Dolan",
"message": "Reject all overlong UTF8 sequences."
},
{
"name": "Stephen Dolan",
"message": "Fix various UTF8 parsing bugs.
In particular, parse bad UTF8 by replacing the broken bits with U+FFFD
and resychronise correctly after broken sequences."
},
{
"name": "Stephen Dolan",
"message": "Fix example in manual for `floor`. See #155."
},
{
"name": "Nicolas Williams",
"message": "Document floor"
}
]
我们可以看到，只要在上一步的命令中内容的两端加个中括号即可。
最后，我们如果想获取每个评论的引用评论的url（在parents节点中，有一个或多个）呢？
7、获取其他内容
jq '[.[] | {message: .commit.message, name: .commit.committer.name, parents: [.parents[].html_url]}]'
结果：
[
{
"parents": [
"https://github.com/stedolan/jq/commit/54b9c9bdb225af5d886466d72f47eafc51acb4f7",
"https://github.com/stedolan/jq/commit/8b1b503609c161fea4b003a7179b3fbb2dd4345a"
],
"name": "Stephen Dolan",
"message": "Merge pull request #162 from stedolan/utf8-fixes
Utf8 fixes. Closes #161"
},
{
"parents": [
"https://github.com/stedolan/jq/commit/ff48bd6ec538b01d1057be8e93b94eef6914e9ef"
],
"name": "Stephen Dolan",
"message": "Reject all overlong UTF8 sequences."
},
{
"parents": [
"https://github.com/stedolan/jq/commit/54b9c9bdb225af5d886466d72f47eafc51acb4f7"
],
"name": "Stephen Dolan",
"message": "Fix various UTF8 parsing bugs.
In particular, parse bad UTF8 by replacing the broken bits with U+FFFD
and resychronise correctly after broken sequences."
},
{
"parents": [
"https://github.com/stedolan/jq/commit/3dcdc582ea993afea3f5503a78a77675967ecdfa"
],
"name": "Stephen Dolan",
"message": "Fix example in manual for `floor`. See #155."
},
{
"parents": [
"https://github.com/stedolan/jq/commit/7c4171d414f647ab08bcd20c76a4d8ed68d9c602"
],
"name": "Nicolas Williams",
"message": "Document floor"
}
]
这里用 .parents[].html_url 获取当前项的 parents 节点中的所有项的 html_url 属性的内容，然后两边加个中括号组装成数组输出。
怎么样，经过这个例子可以看出，用jq处理JSON数据还是很方便强大的吧。
8、注意点
jq能处理的需要是严格的JSON格式数据，JSON对象和JSON字符串是不行的，如下面的两种格式数据jq是不能处理的：
json对象：
{
a: 1,
b: {
c: "abc"
}
}
json字符串：
'{"a":1,"b":{"c":"abc"}}'
正确的JSON格式：
{
"a": 1,
"b": {
"c": "abc"
}
}
关于什么是JSON格式数据，请参考：http://www.json.org/
参考文档：https://www.jianshu.com/p/6de3cfdbdb0e