# Working with ROS2

## CLI

### Node

#### Passing arguments

```bash
ros2 run <ROS_PACKAGE_NAME> <ROS_NODE_NAME> --ros-args -r <ARG>:=<VALUE> -r <ARG>:=<VALUE>
```

for example:

```bash
ros2 run demo_nodes_cpp talker --ros-args -r __ns:=/demo -r __node:=my_talker -r chatter:=my_topic
```

will start `talker` node with name `my_talker` publishing on the topic named `my_topic` instead of the default of `chatter`. The namespace, which must start with a forward slash, is set to `/demo`, which means that topics are created in that namespace (`/demo/my_topic`), as opposed to globally (`/my_topic`).

### Launch

#### Get available launch arguments

```bash
ros2 launch <ROS_PACKAGE_NAME> <LAUNCH_FILE> --show-args
```

#### Passing launch arguments

```bash
ros2 launch <ROS_PACKAGE_NAME> <LAUNCH_FILE> <LAUNCH_ARGUMENT>:=<VALUE>
```

for example:

```bash
ros2 launch turtlebot4_navigation slam.launch.py namespace:="/turtleX"
```