Add unattended installation script for Debian 10/11 and Ubuntu 20.04

[klockren80]

This script has been extensively tested on Debian 10, 11 and Ubuntu 20.04 and seems robust.
I found that the installation instructions a little confusing and they contained a few typos.
I focused on high readability when developing the script.
The distinct steps are divided into functions and individual functions, such as installThumbnailServer, can be commented to exclude that step.

[leadergo]

This is incredible! Your script made it super easy and quick to install and deploy linshare. I did notice that after running the self-install script, I had to edit the hosts file manually to include the following:
127.0.0.1 linshare-user.local
127.0.0.1 linshare-admin.local
127.0.0.1 linshare-upload-request.local

Did you want to include that step in your script?

Also I figure since that script is using an older version of linshare (which still works), I modified the version number to 5.1.2 and it works great!

[Hrsolim]

Hi Everyone,
I tried to run the sh file on Debian11,

it could not run;

: not foundsetup-debian.sh: 20:
: not foundsetup-debian.sh: 26:
: not foundsetup-debian.sh: 28:
unattended-setup-debian.sh: 30: Syntax error: word unexpected (expecting "in")

What is the problem in my work?