Files moved via cli are not shown on Owncloud webpage

Hello everybody.
I' have set up ownclud on raspbian Jessie. What I need to do is move some file in "background" via CLI, however, if I do that, I don't see them on the owncloud https page. Let me give you an example:

root@raspberrypi:~# cp /var/log/syslog /media/ownclouddrive/federico/files/
root@raspberrypi:~# cd /media/ownclouddrive/federico/files/
root@raspberrypi:/media/ownclouddrive/federico/files# ls -l
total 6312
drwxr-xr-x 2 www-data www-data 4096 Jul 23 19:36 Juniper
-rw-r--r-- 1 www-data www-data 4041918 Jul 23 16:40 ownCloud Manual.pdf
drwxr-xr-x 2 www-data www-data 4096 Jul 23 16:40 Photos
-rw-r----- 1 root root 2411808 Jul 24 09:28 syslog
root@raspberrypi:/media/ownclouddrive/federico/files# chown www-data:www-data syslog
root@raspberrypi:/media/ownclouddrive/federico/files# chmod 644 syslog
root@raspberrypi:/media/ownclouddrive/federico/files# ls -l
total 6312
drwxr-xr-x 2 www-data www-data 4096 Jul 23 19:36 Juniper
-rw-r--r-- 1 www-data www-data 4041918 Jul 23 16:40 ownCloud Manual.pdf
drwxr-xr-x 2 www-data www-data 4096 Jul 23 16:40 Photos
-rw-r--r-- 1 www-data www-data 2411808 Jul 24 09:28 syslog

As you can see, despite I have given the right ownership and rights to "syslog" file, I'm not able to see it in my folder on my web page.
Any suggestion?
Thanks

Hi,
Thanks for that. Unfortunately I need to edit file via CLI and push them back into owncloud folder and let them show on GUI. Is there any way to do that?

See the FAQ / solution above how to achieve this.