Can't install Laravel via Composer - php

Question

I have a problem Composer and Laravel. I found a lot of similar topic but it doesn't work. So when I try install Laravel it will show me:
Installing laravel/laravel (v5.5.22)
Installing laravel/laravel (v5.5.22): Loading from cache Created project in sadsa
#php -r "file_exists('.env') || copy('.env.example', '.env');" Loading composer repositories with package information Updating
dependencies (including require-dev) Your requirements could not be
resolved to an installable set of packages.
Problem 1
phpunit/phpunit 6.5.5 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.5.4 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.5.3 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.5.2 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.5.1 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.5.0 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.4.4 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.4.3 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.4.2 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.4.1 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.4.0 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.3.1 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.3.0 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.2.4 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.2.3 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.2.2 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.2.1 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.2.0 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.1.4 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.1.3 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.1.2 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.1.1 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.1.0 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.0.9 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.0.8 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.0.7 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.0.6 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.0.5 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.0.4 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.0.3 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.0.2 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.0.13 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.0.12 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.0.11 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.0.10 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.0.1 requires ext-dom * -> the requested PHP extension dom is missing from your system.
phpunit/phpunit 6.0.0 requires ext-dom * -> the requested PHP extension dom is missing from your system.
Installation request for phpunit/phpunit ~6.0 -> satisfiable by phpunit/phpunit[6.0.0, 6.0.1, 6.0.10, 6.0.11, 6.0.12, 6.0.13, 6.0.2,
6.0.3, 6.0.4, 6.0.5, 6.0.6, 6.0.7, 6.0.8, 6.0.9, 6.1.0, 6.1.1, 6.1.2, 6.1.3, 6.1.4, 6.2.0, 6.2.1, 6.2.2, 6.2.3, 6.2.4, 6.3.0, 6.3.1, 6.4.0, 6.4.1, 6.4.2, 6.4.3, 6.4.4, 6.5.0, 6.5.1, 6.5.2, 6.5.3, 6.5.4, 6.5.5].
To enable extensions, verify that they are enabled in your .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/20-calendar.ini
/etc/php/7.0/cli/conf.d/20-ctype.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-mbstring.ini
/etc/php/7.0/cli/conf.d/20-mcrypt.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-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-xdebug.ini
/etc/php/7.0/cli/conf.d/20-zip.ini You can also run php --ini inside terminal to see which files are used by PHP in CLI mode.
When I try install it globally, I have this but I can't use Laravel new something command:
Changed current directory to /home/michal/.composer
Using version ^1.5 for laravel/installer
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
Nothing to install or update
Generating autoload files
How I said I found a lot of topic but nothing works like install mbstring and so on.

Answer 1

Looks to me it is mainly focus at message requires ext-dom. Possible work around i can suggest is to install following packages:
php-xml
php-common
Or you can try with specific php version as follow:
php7.0-xml
php7.0-common
for php 7.0
sudo apt-get install php7.0-xml

Answer 2

I am using Ubuntu 17.10 and PHP 7.1 is running well using
sudo apt-get install php7.1-xml
If you are using another version of PHP, for example: 7.0 can change it to
sudo apt-get install php7.0-xml
Don't forget to alwasy restart web server, for example in Ubuntu you can type in terminal:
sudo service apache2 reload
After that you can try run composer again. Hope this helps.