File ROS basic courses of study notes 3- System Wizard

1. Preparations
   need to use the following command to install the tutorial ros:
   

   $ sudo apt-get install ros-<distro>-ros-tutorials
   

   Which, distro is the release ros with the tutorial uses kinetic.

   $ sudo apt-get install ros-kinetic-ros-tutorials
   

2. ROS File System Overview
   1. Packages: ROS file system consists of a number of Package, each package may contain libraries (Libraries), executable programs, scripts or other artificial materials written.
   2. The Manifests ( the package.xml ) : package description files.
3. Documentation System Tools command
   1. rospack
      rospack to obtain package (Package) related information, only gives rospack find use in the tutorial, the command returns a packet path
      usage:
      
      

      $ rospack find [package_name]
      

      E.g:

      $ rospack find roscpp
      

       Returns:

      YOUR_INSTALL_PATH/share/roscpp
      

       He returned on the machine as follows:

      /opt/ros/kinetic/share/roscpp
      

       

   2. roscd
      roscd is rosbash part of the change to the directory, or enter a directory, similar to the cd command.
      E.g:
      

      $ roscd roscpp
      

      It represents the current directory becomes roscpp directory.

      Use the pwd command to display the current directory, then:
      

      /opt/ros/kinetic/share/roscpp
      

      Note, ros tool command can only be identified in the environment variable ROS_PACKAGE_PATH package listed, you can extra packages by changing the environment variables will be added to ROS_PACKAGE_PATH path.

      You can use the following command to see which path in this environment variable contains:
      

      $ echo $ROS_PACKAGE_PATH
      

      In this machine returns the following:

      /home/yangbo/mybot_ws/src:/home/yangbo/project_ws/src:/home/yangbo/catkin_ws/src:/home/yangbo/hector_quadrotor_tutorial/src:/opt/ros/kinetic/share:/home/yangbo/px4/Firmware:/home/yangbo/px4/Firmware/Tools/sitl_gazebo
      

      Each separated by a colon.

   3. roscd log
      this command to enter ros log files directory, if there is no log file directory, an error message will be given.
   4. rosls
      rosls also rosbash part that lists all files and directories in a package.
      For example, use the following command to view all files and directories in roscpp_tutorials:
      

      $ rosls roscpp_tutorials
      

      Returns:

      cmake  launch  package.xml  srv
      

       

   5. TAB automatically
      ros command line utility supports the TAB done automatically, for example, you can not remember the full name of each package, but know that at the beginning, you can use TAB completion.

      $ roscd roscpp_tut<<< now push the TAB key >>>
      

       Roscd roscpp_tut example, the input and press the TAB key, the beginning of the package is done automatically roscpp_tut.

      roscd roscpp_tutorials/
      

      If you have the same name and the beginning of the multiple packages is done automatically and the beginning of the closest one, then click the TAB and all options will be listed at the beginning of the match, for example:

      roscd tour
      

       Press the TAB is auto-complete are:

      roscd turtle
      

       Then click the TAB to list all packages beginning tur:

      turtle_actionlib/        turtlebot_navigation/    turtlesim/
      turtlebot_bringup/       turtlebot_simulator/     turtle_tf/
      turtlebot_capabilities/  turtlebot_stage/         turtle_tf2/
      turtlebot_description/   turtlebot_stdr/          
      turtlebot_gazebo/        turtlebot_teleop/