Hi all.  I’m new in Ros, and needing some help to follow the tutorials.

 When I  type ( $ rostopic pub  -1  /turtle1/cmd_vel geometry_msg/Twist  -- `[2.0, 0.0, 0.0]´ ´[0.0, 0.0, 1.8] )

   The previous command sends a message to turtlesim  to move an linear velocity of 2.0 and an angular velocity of 1.8.

I get  this         ( ERROR: invalid message type: geometry_msg/Twist. )

Anibody cam tel me where did I  go wrong?

I´m using ros hidro on ubuntu 12 lts, inside a virtualbox vm.

 Thanks for all.