Can any one help me to code turtle robot which moves only one revolution in circular path?

edit

This my code I tried so many times but failed to get exact output

#!/usr/bin/env python

import rospy
from geometry_msgs.msg import Twist
from turtlesim.msg import Pose

import sys

robot_x = 0
distance = 0


def pose_callback(pose):
    global robot_x
    rospy.loginfo("Robot X = %f\n",pose.x)
    robot_x = pose.x

def move_turtle(lin_vel,ang_vel):

    global robot_x

    rospy.init_node('move_turtle', anonymous=True)
    pub = rospy.Publisher('/turtle1/cmd_vel', Twist, queue_size=10)

    rospy.Subscriber('/turtle1/pose',Pose, pose_callback)

    rate = rospy.Rate(10) # 10hz

    vel = Twist()
    while not rospy.is_shutdown():

    vel.linear.x = lin_vel
    vel.linear.y = 0
    vel.linear.z = 0

    vel.angular.x = 0
    vel.angular.y = 0
    vel.angular.z = ang_vel



        rospy.loginfo("Linear Vel = %f: Angular Vel = %f",lin_vel,ang_vel)
        global distance  
        distance = 2*(3.1415)*(lin_vel/ang_vel)

        if(robot_x == distance):

             rospy.loginfo("Robot Reached destination")
         rospy.logwarn("Stopping robot")

             break


        pub.publish(vel)

        rate.sleep()

if __name__ == '_main_':
    try:
        move_turtle(float(sys.argv[1]),float(sys.argv[2]))
    except rospy.ROSInterruptException:
        pass