OwnCloud

  $ sudo curl https://download.owncloud.org/download/repositories/stable/Debian_9.0/Release.key | sudo apt-key add -
  # $ sudo curl https://download.owncloud.org/download/repositories/stable/Ubuntu_16.04/Release.key | sudo apt-key add -
      . . .
        % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                       Dload  Upload   Total   Spent    Left  Speed
      100  1358  100  1358    0     0   2057      0 --:--:-- --:--:-- --:--:--  2057
      OK
  $ echo 'deb https://download.owncloud.org/download/repositories/stable/Ubuntu_16.04/ /' | sudo tee /etc/apt/sources.list.d/owncloud.list
      deb https://download.owncloud.org/download/repositories/stable/Ubuntu_16.04/ /

  $ sudo apt-get update
      W: https://download.owncloud.org/download/repositories/stable/Ubuntu_16.04/Release.gpg: Signature by key DDA2C105C4B73A6649AD2BBD47AE7F72479BC94B uses weak digest algorithm (SHA1)

  $ sudo apt-get install owncloud-files

  # install php5 modules
  $ sudo apt-get install php7.0-zip php7.0-intl php7.0-gd 

  # psql
  $ sudo apt-get install postgresql
  $ su - postgres
  $ psql

  postgres=# CREATE DATABASE owncloud;
      CREATE DATABASE
  postgres=# CREATE USER ocuser WITH PASSWORD 'your_password';
      CREATE ROLE
  postgres=# GRANT ALL PRIVILEGES ON DATABASE owncloud to ocuser;
      GRANT
  postgres=# \q

  $ nano /etc/apache2/sites-available/owncloud.conf
      </etc/apache2/sites-available/owncloud.conf>
          <VirtualHost *:80>
              # ServerAdmin admin@example.com
              DocumentRoot /var/www/owncloud/
              # ServerName example.com
              # ServerAlias www.example.com
              ServerName localhost
              # Alias /owncloud "/var/www/owncloud/"
              <Directory /var/www/owncloud/>
                  Options +FollowSymlinks
                  AllowOverride All
                  Require all granted
                  <IfModule mod_dav.c>
                      Dav off
                  </IfModule>
                  SetEnv HOME /var/www/owncloud
                  SetEnv HTTP_HOME /var/www/owncloud
              </Directory>
              ErrorLog ${APACHE_LOG_DIR}/error.log
              CustomLog ${APACHE_LOG_DIR}/access.log combined
          </VirtualHost>

  $ a2ensite owncloud.conf; a2enmod rewrite; a2enmod headers; a2enmod env; a2enmod dir; a2enmod mime
  $ systemctl restart apache2.service