Linux curl command operation example summary

curl is an open source file transfer tool that can be used in Linux systems. If you want to use this tool well, you need to know the curl command parameters in detail. The following small series will introduce you to the operation example of the Linux curl command. Interested in Friends can come to understand.

uploading and downloading files on Linux curl support, is a comprehensive transfer tool, but traditionally, used to refer to url to download tools.

Syntax: # curl [option] [url]

Common parameters:

-A/--user-agent "string" Set user agent to send to server

-b/--cookie "name=string/file" cookie string or file read location

-c/--cookie-jar "file" Write the cookie to the end of the operation In this file

-C/--continue-at "offset" breakpoints continue

-D/--dump-header "file" Write header information to this file

-e/--referer Source URL

-f/--fail Does not display http error when connection fails

-o/--output Write output to this

-O/--remote-name in the file Write the output to this file, keep the file name of the remote file

-r/--range "range" Retrieve from HTTP/1.1 Or FTP server byte range

-s/--silent silent mode. Do not output anything

-T/--upload-file "file" Upload file

-u/--user "user[:password]" Set server user and password

-w/--write-out [format] After the output is complete

-x/--proxy "host[:port]" Use HTTP proxy on the given port

-#/--progress-bar The progress bar shows the current transfer status

Example:

1. Basic usage

# curl http://www. Linuxidc.com

After execution, the html of www.linuxidc.com will be displayed on the screen.

Ps: Since linux is installed many times, there is no desktop installed, which means There is no browser, so this method is also often used to test whether a server can reach a website

2. Save the accessed webpage

2.1: Save using linux redirection function

# curl http://www.linuxidc.com 》 linuxidc.html

2.2: You can use curl's built-in option:-o (lowercase) to save the page

$ curl -o linuxidc.html http://www.linuxidc.com

After the completion of the operation, the following interface will be displayed. If 100% is displayed, the save is successful

% Total % Received % Xferd Average Speed ​​Time Time Time Current

Dload Upload Total Spent Left Speed

100 79684 0 79684 0 0 3437k 0 --:--:-- --:--:-- --: --:-- 7781k

2.3: You can use curl's built-in option: -O (uppercase) to save the file in the web page

Note that the url after this is specific to a file. Otherwise, you can't catch it

# curl -O http://www.linuxidc.com/hello.sh

3. Test page return value

# curl -o /Dev/null -s -w %{http_code} www.linuxidc.com

Ps: In the script, this is a very common test for the normal use of the website

4, specify the proxy server And its port

Many times you need to use a proxy server for the Internet (for example, when using a proxy server to access the Internet or being blocked by someone else using the curl website), Fortunately, curl supports setting the proxy by using the built-in option:-x

# curl -x 192.168.100.100:1080 http://www.linuxidc.com

5, cookie

Some websites use cookies to record session information. For browsers such as chrome, cookie information can be handled easily, but it can be easily handled by adding relevant parameters in curl

5.1: Save the cookie information in http response. Built-in option:-c (lowercase)

# curl -c cookiec.txt http://www.linuxidc.com

After the execution, the cookie information is stored in cookiec.txt. Br>

5.2: Save the header information in http response. Built-in option: -D

# curl -D cookied.txt http://www.linuxidc.com

After the execution, the cookie information is saved in cookied.txt

Note: The cookie generated by -c (lowercase) is not the same as the cookie of -D.

5.3: Using Cookies

Many websites monitor your cookie information to determine if you are accessing their website in accordance with the rules, so we need to use the saved cookie information. Built-in option: -b

# curl -b cookiec.txt http://www.linuxidc.com

6. Imitating the browser

Some websites need to use specific The browser goes to access them, and some also need to use certain versions. Curl built-in option: -A allows us to specify a browser to access the website

# curl -A “Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.0)” http://www.linuxidc. Com

This will be considered by the server to use IE8.0 to access

7. Forge referer (the chain of stolen)

Many servers will check the referer of http access. To control access. For example: you first visit the home page, and then visit the mailbox page in the home page. The referer address of the access mailbox is the address of the page after the successful home page. If the server finds that the referer address of the mailbox page access is not the address of the home page, it is determined that Is a stealing

Curl built-in option:-e allows us to set referer

# curl -e “www.linuxidc.com” http://mail.linuxidc.com

This will cause the server to think that you are clicking on a link from www.linuxidc.com

8. Download the file

8.1: Use curl to download the file.

#使用内置::o(lowercase)

# curl -o dodo1.jpg http:www.linuxidc.com/dodo1.JPG

#Use built-in option :-O(uppercase)

# curl -O http://www.linuxidc.com/dodo1.JPG

This will save the file to the local name on the server

8.2: Loop download

Sometimes the download image can be the same as the previous part name, the last tail name is different

# curl -O http://www .linuxidc.com/dodo[1-5].JPG

This will save dodo1, dodo2, dodo3, dodo4, dodo5 all

8.3: Download Rename

# curl -O http://www.linuxidc.com/{hello,bb}/dodo[1-5].JPG

Since the downloaded file names for hello and bb are both dodo1, Dodo2, dodo3, dodo4, dodo5. So the second download will overwrite the first download, so you will need to rename the file.

# curl -o #1_#2.JPG http://www.linuxidc.com/{hello,bb}/dodo[1-5].JPG

This is in hello/The file dodo1.JPG will be downloaded as hello_dodo1.JPG, and other files and so on, effectively avoiding file overwriting.
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