Detailed explanation of Linux curl command

Detailed explanation of curl command in Linux

Abstract: curl is a powerful command line tool used for data communication with the server. This article will introduce the basic usage of the curl command and provide actual code examples to help readers better understand and apply the command.

1. What is curl?
curl is a command line tool used to send and receive various network requests. It supports multiple protocols, such as HTTP, FTP, TELNET, etc., and provides rich functions, such as file upload, file download, data transfer, proxy settings, etc. With its simplicity, ease of use and flexibility, curl has become the preferred data transfer tool in Linux systems and other operating systems.

2. Basic usage of curl

1. Send HTTP request
   Using curl to send HTTP request is very simple. You only need to specify the target URL, and curl will automatically select the corresponding protocol based on the URL. .

For example, send a GET request:

curl https://www.example.com/api/path

Send a POST request:

curl -X POST -d "param1=value1&param2=value2" https://www.example.com/api/path

2. File upload and download
   curl can conveniently perform file uploads and download operations.

File upload:

curl -F "file=@/path/to/file" https://www.example.com/upload

File download:

curl -o /path/to/save/file https://www.example.com/file

3. Set request header
   curl can set the request header through the -H option.

For example, to send a GET request with custom request headers:

curl -H "Content-Type: application/json" https://www.example.com/api/path

4. Use a proxy
   If you need to send the request through a proxy server, you can use the -x option .

For example, send a GET request through a proxy server:

curl -x proxy.example.com:8080 https://www.example.com/api/path

3. Advanced usage of curl

1. Carrying cookies
   curl can be sent carrying cookies To request, use the -C option.

For example, send a GET request with cookie:

curl -b "sessionid=123456" https://www.example.com/api/path

2. Breakpoint resume transmission
   curl supports the breakpoint resume function, use the -C option.

For example, to continue downloading a file from the location of the last download:

curl -C - -o /path/to/save/file https://www.example.com/file

3. Concurrent requests
   curl can achieve concurrent operations by sending multiple requests at the same time.

For example, send two GET requests at the same time:

curl https://www.example.com/api/path1 & curl https://www.example.com/api/path2

IV. Summary
This article details the basic usage and some advanced usage of the Linux curl command, including sending HTTP Requests, file uploads and downloads, setting request headers, using proxies, carrying cookies, resuming uploads and concurrent requests, etc. It is hoped that through the introduction and examples of this article, readers can better master and apply the curl command and improve the efficiency of server data communication.

(Number of words: 516 words)

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