使用 fopen（$ file，'w'） 将文本文件加载到表单中，但是该文件不可写，并且无法保存更改。显然是权限问题，但出于明显的安全原因，我不想将它们更改为777。有没有办法立即执行此操作，然后在保存后将其更改回原来的状态？

<?php $file = "$ServerRoot/text/test.txt";
// $ServerRoot is defined elsewhere and is to the root of the filesystem

// Retrieve the submitted changes and save to the file
if ($_SERVER['REQUEST_METHOD'] === "POST") :
    $fh = fopen($file,'w') or die("Can't open file for writing.");
    fwrite($fh,$_POST['textfield']);
    fclose($fh);
    echo "Content saved.";
endif;

// FOR DIAGNOSTIC PURPOSES ONLY
$TestFile = (file_exists($file)) ? "The file exists\n" : "The file does <font color=\"red\">NOT</font> exist\n";
$TestFile .= (is_readable($file)) ? "The file is readable\n" : "The file is <font color=\"red\">NOT</font> readable\n";
$TestFile .= (is_writable($file)) ? "The file is writable\n" : "The file is <font color=\"red\">NOT</font> writable\n";
$TestFile = nl2br($TestFile);

// Read the textfile
$text = file_get_contents($file);?>

<div align="center">
<?=$TestFile;?>
    <form action="<?=$submitFormaction;?>" method="post">
        <div><input type="submit" value="Save File" />
        <input type="reset" value="Reset"/></div>
        <div><textarea name="textfield" rows="25" cols="85"><?=htmlspecialchars($text);?></textarea></div>
        <div><input type="submit" value="Save File" />
        <input type="reset" value="Reset"/></div>
    </form>
</div>