Indeed, in terms of ethics we should download from sites that only
carry materials in the public domain, GPL (GNU Public License) , or
otherwise legally distributed. One such source is the Internet Archive.

http://www.archive.org

Using the search string

linux AND NOT Arabic AND mediatype:texts

I just downloaded 7 Linux and BASH items. (I can muddle around in
some western European languages, but not at all in Arabic.) In
addition to subjects I wanted, the Internet Achieve has text materials
on Linux about uploading video, fonts, firewalls, connecting Ubuntu to
the Internet, and philosophy of Linux. Substituting "GNU" or
"Internet" for "Linux" locates more resources. I did *not* search for
audio and moving image resource types. Further afield, I found texts
on digital logic and digital communications.