Newbie in running a package

edit

Hi everyone I followed the wiki pages to create and run a simple node but I am getting this error message :

[rosrun] Couldn't find executable named talker_node below /home/bc/catkin_ws/src/my_package

What I did is :

  mkdir -p ~/catkin_ws/src

    cd catkin_ws/
    catkin_make
    cd src/
    catkin_create_pkg my_package std_msgs rospy roscpp
    cd my_package/src/

Copied a talker.cpp file here (/home/bc/catkin_ws/src/my_package/src/)

Added following lines to /home/bc/catkin_ws/src/my_package/CMakeLists.txt file

add_executable(talker_node src/talker.cpp)
target_link_libraries (talker_node ${catkin_LIBRARIES})

File content :

cmake_minimum_required(VERSION 2.8.3)
project(my_package)

find_package(catkin REQUIRED COMPONENTS
  roscpp
  rospy
  std_msgs
)
add_executable(talker_node src/talker.cpp)
target_link_libraries (talker_node ${catkin_LIBRARIES})

include_directories(
  ${catkin_INCLUDE_DIRS}
)

finally I compile the code in /home/bc/catkin_ws directory with running

catkin_make

The output:

Base path: /home/bc/catkin_ws
Source space: /home/bc/catkin_ws/src
Build space: /home/bc/catkin_ws/build
Devel space: /home/bc/catkin_ws/devel
Install space: /home/bc/catkin_ws/install
####
#### Running command: "make cmake_check_build_system" in "/home/bc/catkin_ws/build"
####
-- Using CATKIN_DEVEL_PREFIX: /home/bc/catkin_ws/devel
-- Using CMAKE_PREFIX_PATH: /home/bc/catkin_ws/devel;/opt/ros/melodic
-- This workspace overlays: /home/bc/catkin_ws/devel;/opt/ros/melodic
-- Found PythonInterp: /usr/bin/python2 (found suitable version "2.7.17", minimum required is "2") 
-- Using PYTHON_EXECUTABLE: /usr/bin/python2
-- Using Debian Python package layout
-- Using empy: /usr/bin/empy
-- Using CATKIN_ENABLE_TESTING: ON
-- Call enable_testing()
-- Using CATKIN_TEST_RESULTS_DIR: /home/bc/catkin_ws/build/test_results
-- Found gtest sources under '/usr/src/googletest': gtests will be built
-- Found gmock sources under '/usr/src/googletest': gmock will be built
-- Found PythonInterp: /usr/bin/python2 (found version "2.7.17") 
-- Using Python nosetests: /usr/bin/nosetests-2.7
-- catkin 0.7.20
-- BUILD_SHARED_LIBS is on
-- BUILD_SHARED_LIBS is on
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- ~~  traversing 1 packages in topological order:
-- ~~  - my_package
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- +++ processing catkin package: 'my_package'
-- ==> add_subdirectory(my_package)
-- Configuring done
-- Generating done
-- Build files have been written to: /home/bc/catkin_ws/build
####
#### Running command: "make -j4 -l4" in "/home/bc/catkin_ws/build"
####
Scanning dependencies of target talker_node
[ 50%] Building CXX object my_package/CMakeFiles/talker_node.dir/src/talker.cpp.o
[100%] Linking CXX executable talker_node
[100%] Built target talker_node

But If I try to run

 rosrun my_package talker_node

I get the error message

[rosrun] Couldn't find executable named talker_node below /home/bc/catkin_ws/src/my_package

What should I do ??? Please help me Thanks.