[PHP] split a large file to parts and merge them back to a file

//split 

$filename = 'bigzip.zip';//in public folder

$MBperPart = 45;

$handle1 = fopen($filename, 'r');

$kbcount = 0;

$part = 0;

$handle2 = fopen($filename.'_part_'.$part, 'w');

while (!feof($handle1)) {

$data = fread($handle1, 1024);

fwrite($handle2, $data, strlen($data));

$kbcount++;

if($kbcount == 1024*$MBperPart){

fclose($handle2);

$part++;

$handle2 = fopen($filename.'_part_'.$part, 'w');

$kbcount = 0;

}

}

fclose($handle1);

fclose($handle2);

---

//merge

$filename = 'bigzip.zip'; //bigzip.zip_part_0 , bigzip.zip_part_1 , bigzip.zip_part_2

//rightclick Download > Copy Link Address at GH

$partnum = 10; //if 10 -> 0,1,2,3,4,5,6,7,8,9

header('Content-Disposition: attachment; filename="' . end(explode('/',$filename)) . '"');

//define downloaded file name for client

for ($i = 0; $i < $partnum; $i++) {

$handle1 = fopen($filename . '_part_'.$i, 'rb');

while (!feof($handle1)) {

$data = fread($handle1, 1024);

echo $data;

flush(); //output to client browser and clear buffer (free RAM)

ob_flush(); //output to client browser and clear buffer (free RAM)

}

fclose($handle1);

}