今天部署一台新的服务器，部署好后发现验证码不能正确显示。检查了代码，确定没有问题，用Fiddle抓取了验证码的数据，看到有BOM，不知道修改哪个文件的时候带进去了。文件太多，不好查找，于是写了以下脚本，自动查找当前目录下的php文件，如果含有BOM，尝试清除，如果清除失败，会提示，进行手动修改。

PHP代码：<code>

class BomCleaner
{
    private $files = array();
    private $cleaned = array();
    private $uncleaned = array();

    public function clean($base_dir)
    {
        $this->walk_files($base_dir);
        foreach($this->files as $file)
        {
            $state = $this->clean_bom($file);
            if( $state==1 )
                $this->uncleaned[] = $file;
            elseif( $state==2 )
                $this->cleaned[] = $file;
        }
        $this->show_result();
    }

    private function walk_files($dir, $suffix='php')
    {
        foreach( glob($dir.'/*') as $file )
        {
            if( is_dir($file) )
                $this->walk_files($file);
            elseif( is_file($file) && preg_match('/'.$suffix.'$/is', $file) )
                $this->files[] = $file;
        }
    }

    private function clean_bom($file)
    {
        $head = file_get_contents($file, false, null, 0, 3);
        if( bin2hex($head)=='efbbbf' )
        {
            if( !is_writable($file) )
                return 1;

            $data = file_get_contents($file, false, null, 3);
            file_put_contents($file, $data);
            return 2;
        }
        return 0;
    }

    private function show_result()
    {
        if( !$this->cleaned && !$this->uncleaned )
        {
            die('No BOM file found!');
        }
        else
        {
            echo 'Cleaned '.count($this->cleaned).' files: ';
            echo '<ol>';
            foreach($this->cleaned as $file)
                echo '<li>'.$file.'</li>';
            echo '</ol>';

            echo 'Uncleaned '.count($this->uncleaned).' files: (not writeable)';
            echo '<ol>';
            foreach($this->uncleaned as $file)
                echo '<li>'.$file.'</li>';
            echo '</ol>';
        }
    }
}

$cleaner = new BomCleaner;
$cleaner->clean(__DIR__);

</code>

Linux脚本

在linux下，可用以下脚本一键解决，更方便

<code>find . -type f -exec sed -i 's/\xEF\xBB\xBF//' {} ;</code>