ROS Launch or ROS Run? Understanding the Differences Between Two Essential ROS Commands

When working with the Robot Operating System (ROS), two commonly used commands are rosrun and roslaunch. Both commands are used to start ROS nodes, but there are some key differences between them. In this blog post, we will elaborate on the difference between rosrun and roslaunch commands in ROS.

Also Read: Core of ROS

rosrun

The rosrun command is used to run a single ROS node. The syntax of the command is as follows:

rosrun package_name node_name [args]

In this command, package_name is the name of the package that contains the node to be run, node_name is the name of the node to be run, and [args] are optional arguments that can be passed to the node. The rosrun command is useful when you want to run a single node or when you want to run a node directly from the command line.

For example, the following command will run the turtlebot_teleop_key node from the turtlebot_teleop package:

rosrun turtlebot_teleop turtlebot_teleop_key

roslaunch

The roslaunch command is used to launch one or more ROS nodes from one or more packages. The syntax of the command is as follows:

roslaunch package_name launch_file_name.launch [args]

In this command, package_name is the name of the package that contains the launch file to be run, launch_file_name.launch is the name of the launch file to be run, and [args] are optional arguments that can be passed to the launch file. The roslaunch command is useful when you want to launch multiple nodes that are defined in a launch file.

For example, the following command will launch the turtlebot_gazebo package, which includes multiple nodes for simulating a TurtleBot robot in the Gazebo simulator:

roslaunch turtlebot_gazebo turtlebot_world.launch

Difference between rosrun and roslaunch

The main difference between rosrun and roslaunch is that rosrun is used to run a single node, while roslaunch is used to launch multiple nodes from one or more packages. Additionally, rosrun is typically used to run nodes directly from the command line, while "roslaunch" is typically used to launch nodes from a launch file.

Another key difference is that roslaunch provides more options for configuring and customizing the nodes that are launched. For example, you can use the args parameter to pass arguments to a launch file, and you can use the remap parameter to remap topic names or service names.

In summary, rosrun and roslaunch are both important commands in ROS, but they are used for different purposes. rosrun is used to run a single node, while roslaunch is used to launch multiple nodes from one or more packages. Understanding the differences between these two commands is important for developing and debugging ROS applications.