What is OwnCloud?

Owncloud is like an free/libre open source self-hostable google docs or dropbox

OwnCloud is a suite of client-server software for creating file hosting services and using them. OwnCloud is functionally very similar to the widely used Dropbox, with the primary functional difference being that OwnCloud is free and open-source, and thereby allowing anyone to install and operate it without charge on a private server.
from https://en.wikipedia.org/wiki/OwnCloud

Why

You want to have your own private document server on your own server that is easy for your non geeky friends and family to use.

Where

On your own Debian GNU/Linux Sid server, what else?

Install

Start from https://owncloud.org/download/
Go to packages https://download.owncloud.org/download/repositories/stable/owncloud/

First install base packages
apt-get install php-zip php-gd apache2 mysql-server

Next install the owncloud packages

 wget -nv https://download.owncloud.org/download/repositories/production/Debian_9.0/Release.key -O Release.key
apt-key add - < Release.key
  echo 'deb http://download.owncloud.org/download/repositories/production/Debian_9.0/ /' > /etc/apt/sources.list.d/owncloud.list
  apt-get update
  apt-get install owncloud-files

emacs /etc/apache2/sites-available# cat 001-owncloud.conf

add the following ode

<IfModule mod_alias.c>
Alias /owncloud /var/www/owncloud/
</IfModule>
<Directory /var/www/owncloud/>
   Options Indexes FollowSymLinks
   Order allow,deny
   allow from all
</Directory>
<VirtualHost *:80>
    ServerAdmin foo@myowncloud.com
    DocumentRoot /var/www/owncloud/
    ErrorLog /var/log/apache2/owncloud.info-error_log
    CustomLog /var/log/apache2/owncloud.info-access_log common
</VirtualHost>root@debian-build-speed:/etc/apache2/sites-available# 

Now enable the site
a2ensite 001-owncloud

Enable rewrite
a2enmod rewrite

1. Find the password for your admin account
   root@debian-build-speed:~# grep pass /etc/mysql/debian.cnf | head -1
   password = XXXX

2. Login with that password
   mysql -u debian-sys-maint -p

3. Check the owncloud password
   mysql -u owncloud -p

setup the file store

mkdir /var/owncloud
chown www-data:www-data /var/owncloud
chmod 750 /var/owncloud

Now reload the apache and

systemctl reload apache2

Now navigate to the new host :
http:///owncloud/index.php

Add in your new password for your admin user.

And setup the database password and files

References

https://doc.owncloud.org/server/latest/admin_manual/installation/
http://xmodulo.com/install-configure-owncloud-debian.html
https://github.com/Ram-Z/PKGBUILDs/blob/master/owncloud-git/owncloud.install
http://techne.alaya.net/?p=13994
http://idroot.net/linux/install-owncloud-9-debian-8/
https://www.howtoforge.com/tutorial/owncloud_9-installation-on-debian_8/
https://www.howtoforge.com/tutorial/owncloud-install-debian-8-jessie/