Duration calculation and control in ROS - furthermore why does this script keep running even after pressing Ctrl-C?

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Hi everyone, I have written some code to make the turtlebot turn around. The code is working. What I want to know is how fast the turtlebot is running and how I can control it. Forexample, how can I ensure that the turtlebot turns 5 degrees in one minute? Last part of the question. After pressing Ctrl-C, the turtlebot stops but the script keeps running. Why? and how can I stop that?

this post does not really help.

went through this post .Does that mean that the while loop below runs 5 times a second regardless of the values I put in the for loops? Or does it mean ROS tries its best to make sure that the loop runs 5 times a second to the best of my machine's ability? Thank you very much.

# 5 HZ
    angle = 5
    r = rospy.Rate(5);
    while not rospy.is_shutdown():
        # code to turn
        for x in range(0,100):
            rospy.loginfo("turn")
            turn_cmd.angular.z = radians(angle) 
            new_angle = (angle + new_angle) % 360
            self.cmd_vel.publish(turn_cmd)
            r.sleep()
         # code to pause  
        for x in range(0,100):
            rospy.loginfo("stop")
            turn_cmd.angular.z = radians(0)
            self.cmd_vel.publish(turn_cmd)

            r.sleep()

def shutdown(self):
    # stop turtlebot
    rospy.loginfo("Stop turning")
    self.cmd_vel.publish(Twist())
    rospy.sleep(1)