We have a cloud system that allows us to open labels as a PDF. I have a bash script that examines the PDF and sends it to the correct printer. The PDF is sent after a button is pressed in a form with target="_blank" I have therefore set PDFs to open with this bash script in Preferences > Applications However, every time I press the button to generate the PDF I get a dialogue dox asking "What should Firefox do with this file". The bash script is selected by default and all I have to do is press OK, but even though "do this automatically" is checked, I get the confirmation box every time. I would like the script to be opened automatically without the dialogue box appearing- how can I do this? The headers the cloud server sends are: < HTTP/1.1 200 200 < Date: Mon, 17 Sep 2018 09:57:26 GMT < Server: Apache/2.4.18 (Ubuntu) < Strict-Transport-Security: max-age=63072000; includeSubdomains < X-Frame-Options: DENY < X-Content-Type-Options: nosniff < Content-Disposition: attachment; filename=DispensaryLabel-95390-1537178247028.pdf < Cache-Control: no-cache < Pragma: no-cache < Content-Encoding: gzip < Content-Length: 1465 < Keep-Alive: timeout=5, max=100 < Connection: Keep-Alive < Content-Type: application/pdf Using Firefox Quantum 62.0 64 bit on Ubuntu 18.04