Is there any way to send code to the roboRIO from the command line, so custom build scripts can be created?
Sure, take a look at the ant scripts in the ~/wpilib/{java, cpp}/current/ant directories. The roboRIO supports SSH, username admin with a blank password.
Note that you want to upload code as lvuser, not admin, to avoid permission problems. If you are switching between languages, you will also want to update the /home/lvuser/robotCommand script as appropriate.
Yup, what Peter said (we got bit by this problem). Do not use the admin user. You will cry.
The ant scripts are a bit difficult to read. If you want an example in an actual programming language (python), check out https://github.com/robotpy/pyfrc/blob/master/lib/pyfrc/mains/cli_deploy.py (obviously we’re uploading different artifacts, so take that into consideration).
Thanks, I was actually creating an interpreter that could run code directly on the roboRIO. I will look into the pyfrc code.