Laravel 5: Fehler beim Erstellen Laravel-Projekt in Ubuntu

Question

Ich habe ein Laravel-Projekt in Windows 7 erstellt, es funktioniert gut.Aber wenn ich es in ubuntu durch Eingabeaufforderung mit Befehl erstellen: Composer create-Projekt Laravel/Laravel Lara, Fehler bekommen

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. 

wie diese

Aber es innerhalb opt/lampp/htdocs den Projektordner erstellen und während ich so in Browser, um diese immer Fehler renne:

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 

Bitte helfen Sie mir, ich bin ein Anfänger in Laravel und Ubuntu. Jede Hilfe wird geschätzt.

Vielen Dank im Voraus.

Answer 1

Installieren Sie mit dem unten Befehl

mbstring

sudo apt install php7.0-mbstring 

versuchen Dann composer install wieder