When I open a DVD in Handbrake, it's scanned and the main title is found by the tool. The output name is also automatically adjusted. Then I may add it to the queue. But I need all titles to be added to the queue automatically with proper names specifying their title number. While now, I need to name them and select from the title combobox and add them one after another. I didn't find Handbrake forum. So I decided to ask here.
SnapOverflow
I don't believe you can do this automatically, but if Simultaneously would serve, Here's an excerpt from the Handbrake Team Documentation
Adding multiple encodes simultaneously
When using the Queue, you may find it beneficial to create multiple Jobs at one time.
If your Source is a Blu-ray, DVD, or other disc or disc-like format with multiple Titles, you may open it with HandBrake and add multiple Titles to the Queue simultaneously.
Additionally, you may open a folder of multiple single-Title videos (excluding discs and disc-like formats) as one virtual Source with multiple Titles using the Open Source dialog, and then add multiple Titles to the Queue.
On Linux, select Add Multiple from the Queue menu, then select the Titles you wish to encode using the presented dialog. Be sure to give each a unique file name.
You may open additional Sources and add them to the Queue in the same manner.
EDIT:
As an alternative you could script write a script that loops through all the files in a given directory and run the same conversion command on all of them utilizing handbrake-cli
If you right-click on the "Add to Queue" button, you will see an option called "Show 'Add All' to Queue".
Click that and you'll get a new button called "Add All". Clicking on that will add all of the titles to your encoding queue.
Be sure to tick Preferences -> General -> 'Automatically name output files' so the files don't overwrite each other!