PHP程序自动获取版本号(git hash or file's modified time)

Versional.php

<?php

namespace bootell\models;

class Versional
{
    /**
     * Get git hash
     *
     * @param int $num
     * @return string
     */
    public static function getGitHash($num = 7)
    {
        $git_hash = exec('git rev-parse HEAD');
        if ($git_hash && is_string($git_hash)) {
            $version = substr($git_hash, 0, $num);
            return $version;
        }
        return 0;
    }

    /**
     * Get modified time by given directory
     *
     * @param $dir
     * @return string
     */
    public static function getModifiedTime($dir)
    {
        if(file_exists($_SERVER['DOCUMENT_ROOT'] . $dir) ) {
            $version = filemtime($_SERVER['DOCUMENT_ROOT'] . $dir);
            return $version;
        }
        return 0;
    }
}