HTTP entry (a): curl view request and response in Bash

HTTP

This paper briefly summarizes the requests and responses of HTTP .

The main purpose of this paper is to summarize and learning content for future reference.

Principles and detailed tutorial can refer to HTTP document (MDN).

This article belongs Ma Taotao all.

Cited herein pictures and text belongs to original author, tort deleted.

If wrong, please point out in the comments area below, welcomed the positive discussions.

Interaction with the server browser

Alternately

Browser is responsible for initiating the request
The server receiving a request port 80
Server is responsible for the content returned ( response )
Responsible browser downloads the response content

HTTP protocol role is to guide the browser and the server how to communicate .

request

Use curl -s -v -H "Mtt: xxx" -- https://www.baidu.comto create a request Bash in and get a response.

Command line Interpretation
theme: : brief information : indicating a request, a response indicating : Add a response header
-s
-v > <
-H

Theme request and response: requesting content:
Request and response screenshot

> GET / HTTP/1.1                GET方法发送请求，获取默认根目录,使用http1.1协议
> Host: www.baidu.com           主机
> User-Agent: curl/7.58.0       用curl7.58这个东西发送的请求
> Accept: */*                   接受服务器返回的任何内容
> Frank: xxx
>                               有一个回车

Different test parameters

curl -X POST -s -v -H "Frank: xxx" -- "https://www.baidu.com"Test
content is requested

POST / HTTP/1.1    因为-x改成了post
Host: www.baidu.com 
User-Agent: curl/7.54.0
Accept: */*
Frank: xxx

curl -X POST -d "1234567890" -s -v -H "Frank: xxx" -- https://www.baidu.comTest
content is requested

POST / HTTP/1.1
Host: www.baidu.com
User-Agent: curl/7.54.0
Accept: */*
Frank: xxx
Content-Length: 10   内容长度为是10
Content-Type: application/x-www-form-urlencoded

1234567890

"-d 1234567890": I want to upload data to Baidu 1234567890

Content-Length: 10: Content length is 10
Content-Type: I want to upload content format

GetIt is to obtain, but only browser content, do not do other things
postpublished, uploaded mean. For example, say I want to register log on, put the data written on the inside -d, and then when the request directly uploaded.

Summary: The requested format

1 动词 路径(HTTP规定必须以/开头) 协议/版本
2 Key1: value1
2 Key2: value2
2 Key3: value3
2 Content-Type: application/x-www-form-urlencoded
2 Host: www.baidu.com
2 User-Agent: curl/7.54.0
3 (永远是回车,用来区分二四部分)
4 要上传的数据

Up request includes four parts, a minimum of three parts. (That is the fourth part can be empty)
第三部分永远都是一个回车（n）
动词有 GET POST PUT(整体更新) PATCH(部分更新) DELETE(删除一些东西) HEAD OPTIONS 等
这里的路径包括「查询参数」，但不包括「锚点」(服务器不看锚点,只看路径)
如果你没有写路径，那么路径默认为 /
第 2 部分中的 Content-Type 标注了第 4 部分的格式

响应

上面三个请求示例，前两个请求对应的响应分别为

HTTP/1.1 200 OK
Accept-Ranges: bytes
Cache-Control: private, no-cache, no-store, proxy-revalidate, no-transform
Connection: Keep-Alive
Content-Length: 2443
Content-Type: text/html(百度返回的时候百度的数据长度和内容的格式)
Date: Tue, 10 Oct 2017 09:14:05 GMT
Etag: "5886041d-98b"
Last-Modified: Mon, 23 Jan 2017 13:24:45 GMT
Pragma: no-cache
Server: bfe/1.0.8.18
Set-Cookie: BDORZ=27315; max-age=86400; domain=.baidu.com; path=/

<!DOCTYPE html>
<!--STATUS OK--><html> <head> 后面太长，省略了……

HTTP/1.1 302 Found
Connection: Keep-Alive
Content-Length: 17931
Content-Type: text/html
Date: Tue, 10 Oct 2017 09:19:47 GMT
Etag: "54d9749e-460b"
Server: bfe/1.0.8.18

<html>
<head>
<meta http-equiv="content-type" content="text/html;charset=utf-8"> 后面太长，省略了……

GET 请求和 POST 请求对应的响应可以一样，也可以不一样
响应的第四部分可以很长

响应的格式

1 协议/版本号 状态码 状态解释
2 Key1: value1
2 Key2: value2
2 Content-Length: 17931
2 Content-Type: text/html
3
4 要下载的内容

• status code is said to server browser, then details see Wikipedia HTTP status code
• 1xx unusual
• 2xx indicates success 200 success (get) 204 created successfully (POST)
• 3xx roll bar represents 301 (formerly of people move out up , where will move to the second part of the location of a key: value in the complaint you) 302 (out of a few days will come back means the server temporary absence )
• 4xx Ah that you are wrong (certainly visitors error for example, you entered the wrong address)
• 5xx represent Well, I was wrong (expressed server wrong a)
• Content-Type part 2 of the label format part 4
Content-Type • part 2 of follow MIME specifications