Week 1: Linux Basics & ROS2 Introduction

Week Overview

Linux Fundamentals

Why Ubuntu 24.04?

• LTS Release: 5 years of support until May 2029
• Official Support: Primary platform for ROS2 Jazzy
• Community: Largest Linux community for support
• User-Friendly: Intuitive graphical interface
• Updated Packages: Python 3.12, latest libraries

Linux File System Structure

username@hostname:~$
# username: Your login name
# hostname: Computer name
# ~: Current directory (home)
# $: Regular user (# means root/admin)

# Print Working Directory (where am I?)
pwd

# List files and directories
ls              # Basic list
ls -l           # Long format (detailed)
ls -a           # Show hidden files
ls -la          # Long format + hidden

# Change Directory
cd Documents    # Go to Documents folder
cd ..           # Go up one level
cd ~            # Go to home directory
cd /            # Go to root directory
cd -            # Go to previous directory

# Create empty file
touch myfile.txt

# Create directory
mkdir myfolder
mkdir -p parent/child/grandchild  # Create nested directories

# Copy files/directories
cp file.txt backup.txt           # Copy file
cp -r folder1 folder2            # Copy directory recursively

# Move/Rename files
mv oldname.txt newname.txt       # Rename file
mv file.txt Documents/           # Move file

# Delete files/directories
rm file.txt                      # Delete file
rm -r folder                     # Delete directory
rm -rf folder                    # Force delete (use with caution!)

# Make file executable
chmod +x script.sh

# Set specific permissions
chmod 755 file.txt    # rwxr-xr-x
chmod 644 file.txt    # rw-r--r--
chmod 600 file.txt    # rw-------

#!/bin/bash
# My first ROS2 setup script

echo "Setting up ROS2 environment..."
source /opt/ros/jazzy/setup.bash
echo "ROS2 environment loaded!"
echo "ROS Distribution: $ROS_DISTRO"
echo "Current directory: $(pwd)"

chmod +x setup_ros2.sh
./setup_ros2.sh

Useful Terminal Tips

ROS2 Introduction

ROS1 vs ROS2

ROS2 Jazzy Jalisco

ROS2 Jazzy Installation

Installation Steps

Step 1: Setup Locale

locale
sudo apt update && sudo apt install locales
sudo locale-gen en_US en_US.UTF-8
sudo update-locale LC_ALL=en_US.UTF-8 LANG=en_US.UTF-8
export LANG=en_US.UTF-8

Step 2: Setup Sources

sudo apt install software-properties-common
sudo add-apt-repository universe
sudo apt update && sudo apt install curl -y
sudo curl -sSL https://raw.githubusercontent.com/ros/rosdistro/master/ros.key \
  -o /usr/share/keyrings/ros-archive-keyring.gpg

Step 3: Add ROS2 Repository

echo "deb [arch=$(dpkg --print-architecture) \
signed-by=/usr/share/keyrings/ros-archive-keyring.gpg] \
http://packages.ros.org/ros2/ubuntu \
$(. /etc/os-release && echo $UBUNTU_CODENAME) main" | \
sudo tee /etc/apt/sources.list.d/ros2.list > /dev/null

sudo apt update
sudo apt upgrade

Step 4: Install ROS2 Jazzy

sudo apt install ros-jazzy-desktop

Step 5: Install Development Tools

sudo apt install ros-dev-tools
sudo apt install python3-colcon-common-extensions
sudo apt install python3-rosdep python3-pip

sudo rosdep init
rosdep update

Environment Setup

# Source ROS2 (temporary)
source /opt/ros/jazzy/setup.bash

# Make it permanent
echo "source /opt/ros/jazzy/setup.bash" >> ~/.bashrc
source ~/.bashrc

Verify Installation

ros2 --help
ros2 doctor
echo $ROS_DISTRO  # Should output: jazzy

ROS2 Command Line Tools

ros2 node       # Work with nodes
ros2 topic      # Work with topics
ros2 service    # Work with services
ros2 action     # Work with actions
ros2 param      # Work with parameters
ros2 pkg        # Work with packages
ros2 run        # Run a node from a package
ros2 launch     # Launch multiple nodes
ros2 interface  # Show message/service/action definitions
ros2 bag        # Record and play back data
ros2 doctor     # Check system status

TurtleSim Tutorial

TurtleSim is a lightweight 2D simulator designed for learning ROS2 concepts.

Running TurtleSim

# Install TurtleSim
sudo apt install ros-jazzy-turtlesim

# Run TurtleSim node
ros2 run turtlesim turtlesim_node

Controlling TurtleSim

# In a NEW terminal, run teleop node
ros2 run turtlesim turtle_teleop_key

# Control with arrow keys

Publishing Commands Directly

# Make turtle move forward
ros2 topic pub /turtle1/cmd_vel geometry_msgs/msg/Twist \
"{linear: {x: 2.0, y: 0.0, z: 0.0}, angular: {x: 0.0, y: 0.0, z: 0.0}}"

# Make turtle rotate
ros2 topic pub /turtle1/cmd_vel geometry_msgs/msg/Twist \
"{linear: {x: 0.0, y: 0.0, z: 0.0}, angular: {x: 0.0, y: 0.0, z: 1.8}}"

TurtleSim Services

# Spawn a new turtle
ros2 service call /spawn turtlesim/srv/Spawn \
"{x: 2.0, y: 2.0, theta: 0.2, name: 'turtle2'}"

# Change pen color
ros2 service call /turtle1/set_pen turtlesim/srv/SetPen \
"{r: 255, g: 0, b: 0, width: 5, off: 0}"

# Clear background
ros2 service call /clear std_srvs/srv/Empty

Inspecting TurtleSim

# List all nodes
ros2 node list

# List all topics
ros2 topic list

# Monitor turtle's position
ros2 topic echo /turtle1/pose

# List parameters
ros2 param list /turtlesim

Week 1 Project: TurtleSim Mastery

Grading Rubric

Resources & References