Terminal Commands

Linux Basic Commands

Here is a list of terminal commands you may find helpful throughout the course.

Command	Description	Example
echo	Displays text in a given location (terminal by default)	echo "hello world"
ls	Lists all files and directories	ls
cd	Moves to a given location	cd auvc_ws
mkdir	Creates an empty directory	mkdir intro_to_python
code	Opens a file or directory in VS Code	code .
sudo	Runs a command with root permissions	sudo apt-get update

ROS 2 Commands

Package Commands

ROS 2 packages are the fundamental building blocks of ROS 2 code. They contain nodes, interfaces, and other resources necessary for ROS 2 applications.

Command	Description	Example
ros2 pkg create	Creates an empty ROS 2 package in the current directory.	ros2 pkg create tutorial --build-type ament_python
colcon build	Compiles ROS 2 packages.	colcon build --packages-select \<PACKAGE_NAME\>

warning

When you create a package with ros pkg create, you MUST run the command inside the src directory within the workspace.

BEFORE running the command, run pwd to print the working directory and ensure the path ends with auvc_ws/src.

warning

When you run colcon build to compile packages in a workspace you MUST run the command in the workspace directory.

BEFORE running the command, run pwd to print the working directory and ensure that the path ends with auvc_ws.

info

If you've just compiled a new package, you will either need to source the workspace before the package is available. To do so, either 1. open a new terminal, 2. run source ~/auvc_ws/install/setup.zsh, or 3. source the .zshrc file with source ~/.zshrc.

Node Commands

Nodes are the executable programs in ROS 2 that perform computation. They can communicate with each other through topics, services, and actions.

Command	Description	Example
ros2 node info	Outputs information about a node.	ros2 node info /publisher
ros2 node list	Outputs a list of running nodes.	ros2 node list

Topic Commands

Topics are the communication channels in ROS 2 that nodes use to exchange messages. They are used for one-to-many communication.

Command	Description	Example
ros2 topic echo	Outputs messages on a topic in the terminal.	ros2 topic echo /tutorial
ros2 topic info	Outputs information about a topic.	ros2 topic info /tutorial
ros2 topic list	Outputs a list of named topics.	ros2 topic info
ros2 topic pub	Publishes data to a topic from the terminal.	ros2 topic pub geometry_msgs/msg/Vector3 "\{x: 1.0, y: 0.0, z: 0.0\}"

Interface Commands

Interfaces are the data structures that nodes use to communicate (i.e., .msg files, .srv files, etc.).

Command	Description	Example
ros2 interface list	Outputs a list of defined interfaces.	ros2 interface list
ros2 interface package	Outputs a list of defined interfaces in a compiled package.	ros2 interface package tutorial
ros2 interface packages	Outputs a list of packages that contain interfaces.	ros2 interface packages
ros2 interface show	Outputs the structure defined within the interface.	ros2 interface show geometry_msgs/msg/Vector3Stamped

Service Commands

Services are a way for nodes to communicate in a request-response manner. They are used for synchronous communication.

Command	Description	Example
ros2 service call	Calls a service from the terminal.	ros2 service call \<SERVICE_NAME\> std_srvs/srv/SetBool "\{data: true}"
ros2 service find	Outputs a list of services of a service type.	ros2 service find std_srvs/srv/SetBool
ros2 service list	Outputs a list of running services.	ros2 service list
ros2 service type	Outputs the type of a running service.	ros2 service type \<SERVICE_NAME\>

Launch Commands

Launch files in ROS 2 are used to start multiple instances of nodes using a single terminal command. These files save you time by eliminating the need to open X terminals to ros2 run X nodes.

Command	Description	Example
ros2 launch	Runs a ROS 2 launch file.	ros2 launch \<PACKAGE_NAME\> \<LAUNCH_FILE\>

virtualenvwrapper Commands

The following are common commands used with virtualenvwrapper to manage Python virtual environments.

Command	Description	Example
mkvirtualenv	Creates a new virtual environment	mkvirtualenv <virtual_environment_name>
rmvirtualenv	Deletes a virtual environment (must be deactivated first)	rmvirtualenv <virtual_environment_name>
deactivate	Deactivates the current virtual environment and returns to system-installed Python	(virtual_environment_name) deactivate
lsvirtualenv	Lists all created virtual environments	lsvirtualenv
workon	Activates or switches to the specified virtual environment	workon <virtual_environment_name>

Reference: virtualenvwrapper Documentation – Command Reference