Hey there! Let's break down why your current setup isn't capturing the uploaded image, and walk through two solid solutions to fix it.

Why $_POST Isn't Working Here #

When you use --data-binary @demo.png in your CURL command, you're sending the image's raw binary data directly in the request body—not as a standard form-encoded POST request. PHP's $_POST superglobal only parses data formatted like a web form submission (application/x-www-form-urlencoded or multipart/form-data), so it can't pick up this raw binary content. That's why you're just seeing an empty or incomplete Array in your output.

Solution 1: Use Standard Multipart Form Upload (Recommended) #

This is the most common and reliable way to upload files, as it aligns with how browsers handle file uploads.

Step 1: Update Your CURL Command #

Replace --data-binary with -F (which specifies a multipart form field):

curl --user name:abc -F "uploaded_image=@demo.png" -i localhost:80/post/index.php --output new.txt

The -F flag tells CURL to send the file as part of a multipart/form-data request, which PHP can parse with the $_FILES superglobal.

Step 2: Modify Your PHP Script (index.php) #

Use $_FILES to access the uploaded file details and save it to your server:

<?php
// Check if a file was uploaded
if (isset($_FILES['uploaded_image'])) {
    // Print the file metadata for debugging
    print_r($_FILES['uploaded_image']);

    // Define the path to save the uploaded file
    $targetPath = './uploaded_demo.png';

    // Move the temporary file to your desired location
    if (move_uploaded_file($_FILES['uploaded_image']['tmp_name'], $targetPath)) {
        echo "Image saved successfully to: " . $targetPath;
    } else {
        echo "Failed to save the image.";
    }
} else {
    echo "No file was uploaded.";
}
?>

Solution 2: Read Raw Request Body (If You Can't Change the CURL Command) #

If you need to keep using --data-binary for some reason, you can read the raw binary data directly from the request body in PHP.

Modify Your PHP Script (index.php) #

Use php://input to fetch the raw data and save it as an image file:

<?php
// Read the raw binary data from the request body
$rawImageData = file_get_contents('php://input');

// Check if data was received
if (!empty($rawImageData)) {
    // Define where to save the image
    $savePath = './received_demo.png';

    // Write the data to a file
    if (file_put_contents($savePath, $rawImageData)) {
        echo "Image received and saved to: " . $savePath;
    } else {
        echo "Failed to write the image to disk.";
    }
} else {
    echo "No image data received.";
}
?>

This method bypasses PHP's form parsing entirely and grabs the exact binary data sent by CURL.

内容的提问来源于stack exchange，提问作者David Cring