Question: I wanted to conduct online screening of candidates for interview purpose and the type of questions include:

1. Multiple choice questions
2. Coding Questions
3. Fill in the blanks
4. Questions required to be answered in few 2-3 lines

I want to create my own questions. User need to register using email id and take the test.
What are the good recommendations for this? Open to both open source, free and paid software.

I already explored Moodle. But one problem I see is, we need to create a course and then create tests. Appreciate your help. Thanks in advance.

Answer: 
As you're using Linux on your PC (good choice btw!), you have `rsync` in its repository and maybe even already installed. A pendant on Android could e.g. be **[Syncopoli](https://f-droid.org/packages/org.amoradi.syncopoli/)**:

[![](https://i.stack.imgur.com/Jws8W.png)](https://i.stack.imgur.com/Jws8W.png) [![](https://i.stack.imgur.com/Cf3rl.png)](https://i.stack.imgur.com/Cf3rl.png)  

Syncopoli (source: [F-Droid](https://f-droid.org/packages/org.amoradi.syncopoli/); click images for larger variants)

This seems to be made for your purpose, as the screenshots show – the example matches your need for photos, but document locations can be added the same way. According to its description it is a one-way sync, but by your question you need it for backup, so it should be fine. Authentication is possible via password or public key, both things you're most likely familiar with as Linux user.
When I want to transfer files from my Android phone and USB is acting up, I use [Cx File Explorer](https://play.google.com/store/apps/details?id=com.cxinventor.file.explorer&hl=de&gl=US&pli=1), which has a feature to open an FTP server which you can then access from your desktop.