在相同目录内新建content.txt、index.php，然后将以下代码复制到index.php中
原理：每秒写入一次文件到content.txt

<?php
    if ($_SERVER['REQUEST_METHOD'] === 'POST') {
        $content = $_POST['content'];
        file_put_contents('content.txt', $content);
        exit;
    }

    $content = file_get_contents('content.txt');
?>
<!DOCTYPE html>
<html lang="zh">
    <head>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <title>网络粘贴板</title>
        <link rel="shortcut icon" href="https://img.meituan.net/video/28612b2cf8c65f3e50a89519f1aa41a1178282.png">
        <link href="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/5.3.3/css/bootstrap.min.css" rel="stylesheet">
        <style>
            body {
                            background-image: url('https://img.meituan.net/video/4536167c4d01d7225c84b7247590c8ab1124921.jpg');
                            background-size: cover;
                            background-repeat: no-repeat;
                            background-position: center;
                            height: 100vh;
                            display: flex;
                            align-items: center;
                            justify-content: center;
                        }
                        .container {
                            background: rgba(255, 255, 255, 0.8);
                            border-radius: 15px;
                            padding: 20px;
                            box-shadow: 0 0 20px rgba(0, 0, 0, 0.5);
                            width: 90%;
                            max-width: 800px;
                        }
                        #editor {
                            width: 100%;
                            height: 400px;
                            resize: none;
                        }
        </style>
        <script>
            function saveContent() {
                            const content = document.getElementById('editor').value;
                            fetch('index.php', {
                                method: 'POST',
                                headers: {
                                    'Content-Type': 'application/x-www-form-urlencoded',
                                },
                                body: 'content=' + encodeURIComponent(content),
                            });
                        }
                        setInterval(saveContent, 1000);
        </script>
    </head>
    <body>
        <div class="container">
            <textarea id="editor" class="form-control"><?php echo htmlspecialchars($content); ?></textarea>
        </div>
    </body>
</html>