PHP显示目录中的随机图像

I am kinda new to PHP.

I am searching a way to make PHP showing 6 random JPG images from a directory, no matter what the imagename is. The other important thing is that all the displayed images should be different.

Do you have any idea what's the easiest way to do it? I know i should use the glob function, but how to limit the images to 6,random and non repeatable?

I have that as code for the moment:

<?php
    $pictures = glob("images/gallery/*.jpg"); 
    $no_pictures = count($pictures)-1;  
    $limit = $no_pictures-5;            
    for( $i = $no_pictures; $i >= $limit; $i--){ 
    echo '<div class="col-md-4 col-sm-6 col-xs-12 wow fadeInUp">
            <a class="thumb" href="'.$pictures[$i].'"><img src="'.$pictures[$i].'" alt="Gallery"/><span class="thumb_overlay"></span></a>
          </div>'; 
}  
?>          

But on image refresh it's not displaying different images, it's just tooking random 6 and keep displaying them all the time.

Files: (Random names used)

images/header/rotate.php
images/header/abstract.jpg
images/header/bird.jpg
images/header/butterfly.jpg
images/header/happy.jpg

HTML:

<img src="images/header/rotate.php" alt="Header" width="400" height="100" />

PHP:

<?php

/*
Check it out for more interesting scripts & downloads

AUTOMATIC IMAGE ROTATOR
Version 2.2 - December 4, 2003
Copyright (c) 2002-2003 Dan P. Benjamin, Automatic, Ltd.
All Rights Reserved.
http://www.hiveware.com/imagerotator.php

*/

$folder = '.';


$extList = array();
$extList['gif'] = 'image/gif';
$extList['jpg'] = 'image/jpeg';
$extList['jpeg'] = 'image/jpeg';
$extList['png'] = 'image/png';


// You don't need to edit anything after this point.


// --------------------- END CONFIGURATION -----------------------

$img = null;

if (substr($folder,-1) != '/') {
$folder = $folder.'/';
}

if (isset($_GET['img'])) {
$imageInfo = pathinfo($_GET['img']);
if (
    isset( $extList[ strtolower( $imageInfo['extension'] ) ] ) &&
      file_exists( $folder.$imageInfo['basename'] )
      ) {
      $img = $folder.$imageInfo['basename'];
    }
    } else {
    $fileList = array();
    $handle = opendir($folder);
    while ( false !== ( $file = readdir($handle) ) ) {
    $file_info = pathinfo($file);
    if (
        isset( $extList[ strtolower( $file_info['extension'] ) ] )
    ) {
        $fileList[] = $file;
    }
}
closedir($handle);

if (count($fileList) > 0) {
    $imageNumber = time() % count($fileList);
    $img = $folder.$fileList[$imageNumber];
    }
}

if ($img!=null) {
    $imageInfo = pathinfo($img);
    $contentType = 'Content-type: '.$extList[ $imageInfo['extension'] ];
        header ($contentType);
     readfile($img);
} else {
if ( function_exists('imagecreate') ) {
    header ("Content-type: image/png");
    $im = @imagecreate (100, 100)
        or die ("Cannot initialize new GD image stream");
    $background_color = imagecolorallocate ($im, 255, 255, 255);
    $text_color = imagecolorallocate ($im, 0,0,0);
    imagestring ($im, 2, 5, 5,  "IMAGE ERROR", $text_color);
    imagepng ($im);
    imagedestroy($im);
    }
}

?>

Credits for rotator script http://old.marcofolio.net/webdesign/php_random_image_rotation.html