Move the PR2 arm through some predefined points

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I am a beginner with ROS. I am doing a simple task of writing a controller to move the PR2 arm through some predefined points. So, I need the values of [r_shoulder_pan_joint, r_shoulder_lift_joint, r_upper_arm_roll_joint, r_elbow_flex_joint, r_forearm_roll_joint, r_wrist_flex_joint, r_wrist_roll_joint] and similarly for the left arm, for each of these points. I move the PR2 arm through these points using the interactive manipulation, and am trying to listen to a topic to get these joint values. But I don't know what topic publishes these joint values. What topic should I subscribe to for this?