Laravel 5：ubuntuでlaravelプロジェクトを作成中にエラーが発生しました

Question

Windows 7でlaravelプロジェクトを作成しましたが、うまくいきました。コマンドを使用してコマンドプロンプトからubuntuで作成したとき：composer create-project laravel/laravel lara、この

のようなエラー

Your requirements could not be resolved to an installable set of packages. 

Problem 1 
- laravel/framework v5.5.9 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.8 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.7 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.6 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.5 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.4 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.3 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.28 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.27 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.26 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.25 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.24 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.23 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.22 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.21 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.20 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.2 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.19 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.18 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.17 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.16 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.15 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.14 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.13 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.12 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.11 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.10 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.1 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- laravel/framework v5.5.0 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
- Installation request for laravel/framework 5.5.* -> satisfiable by laravel/framework[v5.5.0, v5.5.1, v5.5.10, v5.5.11, v5.5.12, v5.5.13, v5.5.14, v5.5.15, v5.5.16, v5.5.17, v5.5.18, v5.5.19, v5.5.2, v5.5.20, v5.5.21, v5.5.22, v5.5.23, v5.5.24, v5.5.25, v5.5.26, v5.5.27, v5.5.28, v5.5.3, v5.5.4, v5.5.5, v5.5.6, v5.5.7, v5.5.8, v5.5.9]. 

To enable extensions, verify that they are enabled in those .ini files: 
- /etc/php/7.0/cli/php.ini 
- /etc/php/7.0/cli/conf.d/10-opcache.ini 
- /etc/php/7.0/cli/conf.d/10-pdo.ini 
- /etc/php/7.0/cli/conf.d/15-xml.ini 
- /etc/php/7.0/cli/conf.d/20-calendar.ini 
- /etc/php/7.0/cli/conf.d/20-ctype.ini 
- /etc/php/7.0/cli/conf.d/20-dom.ini 
- /etc/php/7.0/cli/conf.d/20-exif.ini 
- /etc/php/7.0/cli/conf.d/20-fileinfo.ini 
- /etc/php/7.0/cli/conf.d/20-ftp.ini 
- /etc/php/7.0/cli/conf.d/20-gettext.ini 
- /etc/php/7.0/cli/conf.d/20-iconv.ini 
- /etc/php/7.0/cli/conf.d/20-json.ini 
- /etc/php/7.0/cli/conf.d/20-phar.ini 
- /etc/php/7.0/cli/conf.d/20-posix.ini 
- /etc/php/7.0/cli/conf.d/20-readline.ini 
- /etc/php/7.0/cli/conf.d/20-shmop.ini 
- /etc/php/7.0/cli/conf.d/20-simplexml.ini 
- /etc/php/7.0/cli/conf.d/20-sockets.ini 
- /etc/php/7.0/cli/conf.d/20-sysvmsg.ini 
- /etc/php/7.0/cli/conf.d/20-sysvsem.ini 
- /etc/php/7.0/cli/conf.d/20-sysvshm.ini 
- /etc/php/7.0/cli/conf.d/20-tokenizer.ini 
- /etc/php/7.0/cli/conf.d/20-wddx.ini 
- /etc/php/7.0/cli/conf.d/20-xmlreader.ini 
- /etc/php/7.0/cli/conf.d/20-xmlwriter.ini 
- /etc/php/7.0/cli/conf.d/20-xsl.ini 
You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode. 

を取得しかし、私はこのようなブラウザでは、この取得中にエラーを実行している間、それはオプトイン/ LAMPP/htdocsの内側にプロジェクトフォルダを作成しています：

Warning: require(/opt/lampp/htdocs/l5/public/../vendor/autoload.php): failed to open stream: No such file or directory in /opt/lampp/htdocs/l5/public/index.php on line 24 

Fatal error: require(): Failed opening required '/opt/lampp/htdocs/l5/public/../vendor/autoload.php' (include_path='.:/opt/lampp/lib/php') in /opt/lampp/htdocs/l5/public/index.php on line 24 

私はこれを手伝ってください、私はlaravelとubuntuの初心者です。 助けていただければ幸いです。

ありがとうございます。

Answer 1

解析エラー私は、このコマンドを実行し、その後laravelプロジェクトを作成している再度