ros package can NOT find, error with [rospack] [closed]

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I just installed ros kinetic on ubuntu 16.04.2. I am trying to run kinect v2, but I failed with several attempts

when I run 'abdulrahman@abdulrahman-ThinkPad-X230-Tablet:~/libfreenect2/build/bin$ ./Protonect', it works fine, but I can not run the following codes

'roscore'
'rosrun kinect2_viewer kinect2_viewer sd cloud'
'rosrun kinect2_bridge kinect2_bridge'

I always get this error

 'abdulrahman@abdulrahman-ThinkPad-X230-Tablet:~$ rosrun kinect2_viewer kinect2_viewer sd cloud'
  '[rospack] Error: package 'kinect2_viewer' not found'

even I tried this, but same error

abdulrahman@abdulrahman-ThinkPad-X230-Tablet:~$ rosrun kinect2_bridge kinect2_bridge _reg_method:=cpu
[rospack] Error: package 'kinect2_bridge' not found

any one can help please ?????