The <group> tag

The <group> tag makes it easier to apply settings to a group of nodes. It has an ns attribute that lets you push the group of nodes into a separate namespace. You can also use the <remap> tag to apply remap setting across the group.

Attributes

• ns="namespace" (optional)

  • Assign the group of nodes to the specified namespace. The namespace can be global or relative, though global namespaces are discouraged.

  clear_params="true|false" (optional)

  • Delete all parameters in the group's namespace before launch. This feature is very dangerous and should be used with caution. ns must be specified.

Elements

The <group> tag is equivalent to the top-level <launch> tag and simply acts as a container for the tags within. This means that you can use any tag as you would normally use it within a <launch> tag.

• <node>

  • Launch a node.

  <param>

  • Set a parameter on the Parameter Server

  <remap>

  • Declare a name remapping.

  <machine>

  • Declare a machine to use for launching.

  <rosparam>

  • Set ROS parameters for the launch using a rosparam file.

  <include>

  • Include other roslaunch files.

  <env>

  • Specify an environment variable for launched nodes.

  <test>

  • Launch a test node (see rostest).

  <arg>

  • Declare an argument.