root@IXPManager:/srv/ixpmanager# composer install |more
Loading composer repositories with package information
Installing dependencies (including require-dev) from lock file
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Installation request for dompdf/dompdf v0.8.0 -> satisfiable by dompdf/dompdf[v0.8.0].
    - dompdf/dompdf v0.8.0 requires ext-gd * -> the requested PHP extension gd is missing from your system.
  Problem 2
    - dompdf/dompdf v0.8.0 requires ext-gd * -> the requested PHP extension gd is missing from your system.
    - barryvdh/laravel-dompdf dev-master requires dompdf/dompdf ^0.8 -> satisfiable by dompdf/dompdf[v0.8.0].
    - Installation request for barryvdh/laravel-dompdf dev-master -> satisfiable by barryvdh/laravel-dompdf[dev-master].

  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-mysqlnd.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-curl.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-intl.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-memcache.ini
    - /etc/php/7.0/cli/conf.d/20-memcached.ini
    - /etc/php/7.0/cli/conf.d/20-mysqli.ini
    - /etc/php/7.0/cli/conf.d/20-pdo_mysql.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-snmp.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
    - /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.