在Ubuntu系统中实现PHP文件上传功能，你需要遵循以下步骤：
<!DOCTYPE html> <html> <head> <title>PHP File Upload</title> </head> <body> <form action="upload.php" method="post" enctype="multipart/form-data"> Select image to upload: <input type="file" name="fileToUpload" id="fileToUpload"> <input type="submit" value="Upload Image" name="submit"> </form> </body> </html> upload.php的PHP文件，用于处理文件上传：<?php $target_dir = "uploads/"; $target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]); $imageFileType = strtolower(pathinfo($target_file,PATHINFO_EXTENSION)); $uploadOk = 1; // Check if image file is an actual image or fake image if(isset($_POST["submit"])) { $check = getimagesize($_FILES["fileToUpload"]["tmp_name"]); if($check !== false) { echo "File is an image - " . $check["mime"] . "."; $uploadOk = 1; } else { echo "File is not an image."; $uploadOk = 0; } } // Check if file already exists if (file_exists($target_file)) { echo "Sorry, file already exists."; $uploadOk = 0; } // Check file size if ($_FILES["fileToUpload"]["size"] > 500000) { echo "Sorry, your file is too large."; $uploadOk = 0; } // Allow certain file formats if($imageFileType != "jpg" && $imageFileType != "png" && $imageFileType != "jpeg" && $imageFileType != "gif" ) { echo "Sorry, only JPG, JPEG, PNG & GIF files are allowed."; $uploadOk = 0; } // Check if $uploadOk is set to 0 by an error if ($uploadOk == 0) { echo "Sorry, your file was not uploaded."; // if everything is ok, try to upload file } else { if (move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $target_file)) { echo "The file ". htmlspecialchars( basename( $_FILES["fileToUpload"]["name"])). " has been uploaded."; } else { echo "Sorry, there was an error uploading your file."; } } ?> sudo apt-get update sudo apt-get install php uploads的文件夹，用于存储上传的文件：mkdir uploads uploads文件夹的权限，以便PHP脚本可以将文件写入该文件夹：chmod 755 uploads 将HTML文件和upload.php文件上传到你的Ubuntu服务器上的一个Web目录（例如：/var/www/html）。
通过浏览器访问HTML文件，然后尝试上传一个文件。如果一切正常，你应该能看到文件已成功上传到uploads文件夹。
注意：在实际生产环境中，你可能需要对文件上传功能进行更多的安全检查和处理，例如限制上传文件的大小、类型和来源等。
