Let Thunderbird create default profile to be able to create user.js

If I start Thunderbird for the first time, it will create a default profile and guide me through an email signup / setup wizard. I'd like to do my this provisioning using a shell script. As a part of my account provisioning, I'd like to create a custom user.js preferences file for Thunderbird . This user.js file might contain custom config entries and preferences for my IMAP/SMTP server. To be able to create a user.js settings file, I need an existing Thunderbird default profile (directory) before. (Where to put my custom user.js file?) The default profile will be a random string like mkxy3j7s.default-release. But I don't know how to predirect this folder name. So I'd like Thunderbird to create this, before I try to write a file into this profile directory. If I run thunderbird --createprofile, it says: Error: argument --createprofile requires a profile name. **Is there a way to have Thunderbird create its default profile for the current user without starting the interactive Thunderbird GUI?** Something like thunderbird --createDefaultProfile would be amazing. So I could do: #!/bin/bash thunderbird --createDefaultProfile findDefaultProfileAndWriteUserJs.sh thunderbird &