Are there specific best practices for managing file uploads and permissions in PHP applications to avoid issues like duplicate files and permission conflicts?

When managing file uploads and permissions in PHP applications, it's important to generate unique filenames to avoid duplicate files. Additionally, setting appropriate permissions on uploaded files can help prevent permission conflicts. One common approach is to use a combination of timestamp and a random string to create unique filenames, and to ensure that uploaded files have the correct permissions set.

// Generate a unique filename for the uploaded file
$timestamp = time();
$random_string = bin2hex(random_bytes(5));
$filename = $timestamp . '_' . $random_string . '_' . $_FILES['file']['name'];

// Move the uploaded file to a designated directory
$upload_dir = 'uploads/';
move_uploaded_file($_FILES['file']['tmp_name'], $upload_dir . $filename);

// Set appropriate permissions on the uploaded file
chmod($upload_dir . $filename, 0644);