$ rospack find [package] # return package directory
$ roscd [path] # change directory to a package or a stack
$ rosls [path] # list files in the package

$ mkdir -p ~/catkin_ws/src
$ cd ~/catkin_ws/src
$ catkin_init_workspace


$ catkin_create_pkg [package_name] [depend1] [depende2] # create a catkin worksapce
$ catkin_make # build the packages

$ roscore # start core service
$ rosnode list # list running nodes
$ rosnode info [node] # return node information
$ rosrun [package] [node_name] #run a node

$ ros rqt_graph rqt_graph

$ rostopic list -v # show topics and their information
$ rostopic type [topic] # get the message type of the topic
$ rostopic pub [topic] [msg_type] [args] # publishes data to a topic
$ rostopic hz [topic] # show the publish rate

$ rosmsg show <msg> #get the information of the message

$ pip install catkin_pkg

$ pip install rosdep

$ pip install empy