It should be geometry_msgs .. you missed the last 's'
 rostopic pub  -1  /turtle1/cmd_vel geometry_msgs/Twist  -- '[2.0, 0.0,
0.0]' '[0.0, 0.0, 1.8]'

Regards
Jit Ray Chowdhury
Co-Founder | AuRo Robotics | www.aurobots.com
(+91) 98315-46599 / 91432-99599 | www.jitrc.com


On Sat, Jul 12, 2014 at 4:31 AM, Davinci <davinci_mgs@hotmail.com> wrote:

>  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.
>
>
>
>
>
>
>
>
>
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>