Example 6.8 needs correction

it should say

roscd;cd …;cd src
catkin_create_pkg my_custom_srv_msg_pkg rospy std_msgs

Hi, you added an extra dot in the command

And if you are referring to the addition of std_msgs while creating the package, it’s true that you can do that, but if you continue in the exercise, you’ll see that the dependencies are included by hand in CMakeLists.txt and package.xml.