Question: how to transfer files from linux to ipad?
Answer: Install Zip & RAR File Extractor in your iPad.
Create a zip folder in your Linux machine of the files which you want to transfer.
Open the Zip extractor app on your iPad, then go to Wi-Fi Transfer. It will show a web address. ... 
Open iPad files, go to "On My iPad" and then go to the "Zip Extractor folder".