<?php

class UpdateMaker
{
    public $path = null;
    public $startTag = null;
    public $endTag =  null;
    public $result = array();

    public function __construct($options)
    {
        $this->path = $options['path'];
        $this->startTag = $options['startTag'];
        $this->endTag = $options['endTag'];
        $this->getModiedFiles();
    }

    public function getModiedFiles()
    {
        $path = $this->path;
        $startTag = $this->startTag;
        $endTag = $this->endTag;
        $oneLineCommand = "cd $path && git diff $startTag $endTag --name-only";
        exec($oneLineCommand, $this->result);
    }

    public function save($path)
    {
        foreach ($this->result as $key => $value)
        {
            $fullPath = $this->path.$value;
            if (file_exists($fullPath))
                $this->result[$key] = $fullPath;
            else
                unset($this->result[$key]);
        }

        $files =  '"'.implode('" "', $this->result).'"';
        $result = array();
        exec("/bin/tar -cf $path $files", $result);
    }
}

$updater = new UpdateMaker(array(
    'path'=>'/var/www/ImageCMS/',
    'startTag'=>'v2.1.6',
    'endTag'=>'v2.5.5',
));

$updater->save('/home/username/result.tar');