setup.bash must source again when restart

edit

why I have to source setup.bash again when restart my computer?

adminyin@adminyin-System:~$ cd catkin_ws/src/
adminyin@adminyin-System:~/catkin_ws/src$ ls
beginner_tutorials  CMakeLists.txt
adminyin@adminyin-System:~/catkin_ws/src$ rospack depends1 beginner_tutorials
[rospack] Error: no such package beginner_tutorials
adminyin@adminyin-System:~/catkin_ws/src$ cd ..
adminyin@adminyin-System:~/catkin_ws$ source devel/setup.bash 
adminyin@adminyin-System:~/catkin_ws$ cd src/
adminyin@adminyin-System:~/catkin_ws/src$ rospack depends1 beginner_tutorials
roscpp