Small script to migrate Bitbucket repositories to GitHub.

run.php

<?php
/**
 * Migrate repositorioes from Bitbucket to GitHub.
 * 
 * Usage: php run.php
 * 
 * @package CS\Bitbucket_to_Github
 * @license MIT License
 */
class CS_Bitbucket_to_Github
{
    const GITHUB_USERNAME = ''; // Your GitHub username.
    const GITHUB_TOKEN = ''; // Your GitHub Token.
    const GITHUB_PRIVATE_REPOS = true;
    const BITBUCKET_USERNAME = ''; // Your Bitbucket username
    const BITBUCKET_REPOSITORIES = []; // Copy your repositories names from Bitbucket. @todo use bitbucket API.

    /**
     * Script current path.
     *
     * @var string
     */
    protected $current_path = '';

    /**
     * Initialize.
     */
    public function __construct()
    {
        $this->current_path = exec('pwd');
    }

    /**
     * Run migration.
     *
     * @return void
     */
    public function run() {
        foreach (self::BITBUCKET_REPOSITORIES as $repo) {
            exec(sprintf('git clone git@bitbucket.org:%s/%s.git', self::BITBUCKET_USERNAME, $repo));
            $this->create_gh_repo($repo);
            exec(sprintf(
                'cd %1$s/%2$s' .
                '&& git remote rename origin bitbucket ' .
                '&& git remote add origin git@github.com:%3$s/%2$s.git ' .
                '&& git push origin master ' .
                '&& git remote remove bitbucket ' .
                '&& cd %1$s ' .
                '&& rm -rf %1$s/%2$s',
                $this->current_path, $repo, self::GITHUB_USERNAME
            ));
        }
    }

    /**
     * Create repository in GitHub.
     *
     * @param string $name Repository name.
     * @return void
     */
    protected function create_gh_repo(string $name)
    {
        $ch = curl_init();
        $data = [
            'name'    => $name,
            'private' => self::GITHUB_PRIVATE_REPOS,
        ];

        curl_setopt_array(
            $ch,
            [
                CURLOPT_URL  => 'https://api.github.com/user/repos',
                CURLOPT_POST => true,
                CURLOPT_POSTFIELDS => json_encode($data),
                CURLOPT_RETURNTRANSFER => true,
                CURLOPT_HTTPHEADER => [
                    'Accept: application/json',
                    'Content-Type: application/json',
                    'Authorization: token '. self::GITHUB_USERNAME,
                    'User-Agent: CS-Bitbucket-to-Github'
                ]
            ]
        );

        $output = curl_exec($ch);

        curl_close($ch);
    }
}

$migrate = new CS_Bitbucket_to_Github();
$migrate->run();
echo 'DONE!';