Examples of curl usage

Keywords: curl PHP Nginx Mac

This article will introduce the use of curl. According to the common scenarios, it will provide the demo code and server code for calling curl to realize the request, which is convenient for everyone to learn and use.

1. View the Web Source Code

The curl command is followed by a web address, so you can see the source code of the web page.

curl www.csdn.net

<html>
<head><title>302 Found</title></head>
<body bgcolor="white">
<center><h1>302 Found</h1></center>
<hr><center>nginx</center>
</body>
</html>

2. Automatic jump

In the example above, because the web site has been jumped, curl defaults to not follow the jump, so only the source code of the first page is obtained. If we want to follow the jump, we can use the - L parameter.

curl -L www.csdn.net

After adding the - L parameter, curl jumps to the new page and returns the source code of the new page.

3. View the source code of the web page and download it.

Save the source code of the page to the file, and use the - o parameter with the save path.

curl -o csdn.viewcode www.csdn.net

After execution, the source code of the web page is saved in the csdn.viewcode file.

4. Display header information

curl -i www.csdn.net

HTTP/1.1 302 Moved Temporarily
Server: openresty
Date: Sun, 17 Dec 2017 09:18:46 GMT
Content-Type: text/html
Content-Length: 154
Connection: keep-alive
Keep-Alive: timeout=20
Location: https://www.csdn.net

<html>
<head><title>302 Found</title></head>
<body bgcolor="white">
<center><h1>302 Found</h1></center>
<hr><center>nginx</center>
</body>
</html>

If you only need to display the header information of http response, use -I

curl -I www.csdn.net

HTTP/1.1 302 Moved Temporarily
Server: openresty
Date: Sun, 17 Dec 2017 09:20:25 GMT
Content-Type: text/html
Content-Length: 154
Connection: keep-alive
Keep-Alive: timeout=20
Location: https://www.csdn.net

5. Display the communication process

curl -v www.csdn.net

* Rebuilt URL to: www.csdn.net/
*   Trying 101.201.172.229...
* Connected to www.csdn.net (101.201.172.229) port 80 (#0)
> GET / HTTP/1.1
> Host: www.csdn.net
> User-Agent: curl/7.49.1
> Accept: */*
> 
< HTTP/1.1 302 Moved Temporarily
< Server: openresty
< Date: Sun, 17 Dec 2017 09:23:06 GMT
< Content-Type: text/html
< Content-Length: 154
< Connection: keep-alive
< Keep-Alive: timeout=20
< Location: https://www.csdn.net
< 
<html>
<head><title>302 Found</title></head>
<body bgcolor="white">
<center><h1>302 Found</h1></center>
<hr><center>nginx</center>
</body>
</html>
* Connection #0 to host www.csdn.net left intact

6. Display detailed communication process

If you want to see a more detailed communication process, you can use the following two parameters.

curl --trace trace.log www.csdn.com

curl --trace-ascii trace.log www.csdn.com

After execution, open trace.log to view.

7. Submit forms

get mode

Data is spliced directly behind the address

curl "localhost/server.php?a=1&b=2&c=3"

Server-side code:

<?php
$param = array('a','b','c');
foreach($param as $v){
    echo $v.'='.(isset($_GET[$v])? $_GET[$v] : '').PHP_EOL;
}
?>

post mode

Data should be separated from address by using the data parameter

curl -X POST --data "a=1&b=2&c=3" "localhost/server.php"

It can also be simplified to

curl -d "a=1&b=2&c=3" "localhost/server.php"

Form coding

If the data is not encoded, the data-urlencode parameter is used to execute the encoding, but a separate parameter is needed to encode it.

curl -X POST --data-urlencode "a=Ha-ha" --data-urlencode "b=Hey" --data-urlencode "c=Ha-ha" "localhost/server.php"

Server-side code:

<?php
$param = array('a','b','c');
foreach($param as $v){
    echo $v.'='.(isset($_POST[$v])? $_POST[$v] : '').PHP_EOL;
}
?>

8. Upload files

For example, the file upload form is as follows:

<form name="form1" method="post" action="test.php" enctype="multipart/form-data">
<p>file:<input type="file" name="file"></p>
<p><input type="submit" value="submit"></p>
</form>

Use the - form or - F parameter

Only upload pictures

curl --form file=@/tmp/photo.jpg localhost/server.php

Upload pictures and submit other parameters

curl -F upload=@/tmp/photo.jpg -F upload_field=upload -F file_path=abc.jpg localhost/server.php

Server-side code:

<?php
$upload_field = isset($_POST['upload_field'])? $_POST['upload_field'] : 'file';
$name = explode('.', $_FILES[$upload_field]['name']);
$file_ext = array_pop($name);
$file_path = isset($_POST['file_path'])? $_POST['file_path'] : time().'.'.$file_ext;

$upload_flag = move_uploaded_file($_FILES[$upload_field]['tmp_name'], dirname(__FILE__).'/'.$file_path);
echo ($upload_flag==1? 'true' : 'false').PHP_EOL;
?>

9. Simulated sources

curl --referer 'www.csdn.net' localhost/server.php

Server-side code:

<?php
echo 'REFERER:'.(isset($_SERVER['HTTP_REFERER'])? $_SERVER['HTTP_REFERER'] : '').PHP_EOL;
?>

10. Analog Client Device

Simulated iPhone Access

curl --user-agent "Mozilla/5.0 (iPhone; CPU iPhone OS 6_0 like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/6.0 Mobile/10A403 Safari/8536.25" localhost/server.php

Simulate chrome access

curl --user-agent "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.94 Safari/537.36" localhost/server.php

Server-side code:

<?php
function isMobile() {
    $agent = $_SERVER['HTTP_USER_AGENT'];
    return stripos($agent, 'iPod;') !== false || stripos($agent, 'iPhone') !== false || stripos($agent, 'Android') !== false || stripos($agent, 'iPad') !== false;
}

echo (isMobile()? 'true' : 'false').PHP_EOL;
?>

Simulated iPhone access returns true, simulated chrome access returns false.

11. Send and receive cookie s

Get the returned cookie

curl -c cookiefile url

Cookies passed on request

curl -b cookiefile url

Server-side code:

<?php
if(isset($_COOKIE['username'])){
    echo $_COOKIE['username'].' is login'.PHP_EOL;
}else{
    $username = isset($_POST['username'])? $_POST['username'] : '';
    $password = isset($_POST['password'])? $_POST['password'] : '';

    if($username=='fdipzone' && $password=='654321'){
        setcookie('username', $username, time()+3600);
        echo 'login success'.PHP_EOL;
    }else{
        echo 'login fail'.PHP_EOL;
    }
}
?>

Access without cookie s

curl localhost/server.php

Post-execution output: login fail

curl -c /tmp/cookie -d "username=fdipzone&password=654321" localhost/server.php

Output after execution: login success
The obtained cookie is saved in the / tmp/cookie file.

Using the acquired cookie access

curl -b /tmp/cookie localhost/server.php

Post-execution output: fdipzone is login
Represents a cookie that can be retrieved for the delivery of the request.

12.header

Bring a custom header when requesting.

curl --header "access-token:RGV2cXgxWHFVbEdVN1o2NFVkSG40Zmo1aXE" --header "lang:zh_CN" localhost/server.php

Server-side code:

<?php
/**
 * Get custom header data
 */
function get_all_headers(){

    // Ignore captured header data
    $ignore = array('host','accept','content-length','content-type');

    $headers = array();

    foreach($_SERVER as $key=>$value){
        if(substr($key, 0, 5)==='HTTP_'){
            $key = substr($key, 5);
            $key = str_replace('_', ' ', $key);
            $key = str_replace(' ', '-', $key);
            $key = strtolower($key);

            if(!in_array($key, $ignore)){
                $headers[$key] = $value;
            }
        }
    }

    return $headers;

}

print_r(get_all_headers());
?>

Output after execution:

Array
(
    [lang] => zh_CN
    [access-token] => RGV2cXgxWHFVbEdVN1o2NFVkSG40Zmo1aXE
    [user-agent] => curl/7.49.1
)

13.HTTP authentication

Some addresses require HTTP authentication, and authentication information can be passed using the user parameter.

curl --user "user:pass" url

Server-side code:

<?php
if(!isset($_SERVER['PHP_AUTH_USER']))   
{   
    header('WWW-Authenticate: Basic realm="localhost"');   
    header("HTTP/1.0 401 Unauthorized");   
    exit('Unauthorized'.PHP_EOL);   
}else{   
    if (($_SERVER['PHP_AUTH_USER']!= "fdipzone" || $_SERVER['PHP_AUTH_PW']!="654321")) {  
        header('WWW-Authenticate: Basic realm="localhost"');  
        header("HTTP/1.0 401 Unauthorized");  
        exit('Unauthorized'.PHP_EOL);  
    }  
}  

$content = isset($_POST['content'])? $_POST['content'] : '';  
header('content-type:application/json');  
echo $content.PHP_EOL;
?>

Request without authentication information

curl -d "content=abc123" localhost/server.php

Post-execution output: Unauthorized

Request with authentication information

curl -d "content=abc123" --user "fdipzone:654321" localhost/server.php

Post-execution output: abc123

Posted by davidcriniti on Thu, 16 May 2019 16:04:56 -0700

Programmer Group

Examples of curl usage

1. View the Web Source Code

2. Automatic jump

3. View the source code of the web page and download it.

4. Display header information

5. Display the communication process

6. Display detailed communication process

7. Submit forms

8. Upload files

9. Simulated sources

10. Analog Client Device

11. Send and receive cookie s

12.header

13.HTTP authentication

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