i used ubuntu 16 and wrote in terminal:

rosrun pcl_ros bag_to_pcd <input_file.bag> <topic> <output_directory>

but i'm getting this error:

[ERROR] [1488830410.790465733]: [registerPublisher] Failed to contact master at [localhost:11311].  Retrying...

Furthermore i tried to change localhost with my ip with command:

export ROS_MASTER_URI=http://X.X.X.X:11311/

but nothing!

Please help,i have no idea how to achieve this conversion!