How do I cartesin plan along the axis of the interactive marker?

edit

You seem to be asking how to apply relative targets in the end effector frame (or whichever you interactive marker is placed on), so I'll repost part of this old question.

You will want to use a PoseStamped object, transform it to the end effector frame in which you want to apply the offset, and then (if necessary) transform it back to the planning frame (usually world or the robot base).

tf::TransformListener tf_listener; // Declared in advance

...

geometry_msgs::PoseStamped pose0 = group.getCurrentPose();
geometry_msgs::PoseStamped pose_in_ee_frame;
tf_listener.transformPose("your_end_effector_frame", pose0, pose_in_ee_frame);
pose_in_ee_frame.pose.position.y -= .05;
tf_listener.transformPose(pose0.header.frame_id, pose_in_ee_frame, pose0);

waypoints.push_back(pose0.pose)
...

PS: From Noetic, you will find a convenient checkbox saying "Use Cartesian Path" in the Rviz plugin. You can also get it by compiling MoveIt from source (which should still be possible on Kinetic at the moment).