Getting around the Pi

Here's a list of commands commonly used on the Pi, grouped by purpose. You'll probably want to be familiar with how we use ROS first.

Getting around

• cd. With no arguments, goes to the home directory. With an argument, changes to that directory. Press TAB while typing an argument to try to autocomplete it. With an argument of .., goes one level up.
• roscd. The evil twin of cd. Takes an argument of the form <PACKAGE> (usually "bike"), or <PACKAGE>/<PATH>. Our code (as of February 2020) is all in the "scripts" directory under the main package directory, which has three subdirectories:
  • Launch, which has ROS launch files. They describe how to start a collection of ROS nodes.
  • Navigation, which is a checkout of our Navigation repo. It has Python navigation files.
  • Startup, which is a checkout of our Startup repo. It has two Bash scripts, that start and end testing runs.

Running things

• We use roslaunch files to start the correct combination of ROS nodes.
• There's a script called start.sh in the home directory of the Pi. It runs the appropriate launch commands. It sets some environment variables, so run it using the command source start.sh <LAUNCH FILE>, where <LAUNCH FILE> is the name of a launch file we use. You can list all of the launch files using rosls bike/scripts/Launch.

Printing things

• rostopic list to write out a list of all the ROS topics that have been DEFINED OR USED (not just the ones that've been published to)
• rostopic echo <TOPIC NAME> to print out a feed of data published to <TOPIC NAME>. Topic names usually start with a forward slash (for example, /nav_instr or /bike_state). Stop it with Ctrl-C. If nothing prints, nothing's being published.

Editing things

Vim and Emacs are installed.