ros hydro runtime resouce localization
Hello! I have a question regarding the basic knowledge about ros (especially hydro), which is, when the ros program starts, how does it locate the needed resources, e.g., libs, executables, etc. ?
Currently I install my ros in /opt/ros/hydro, and in hydro it seems that the source codes are not installed together any more. So if I want to make some changes to some ros pre-installed packages, e.g., ros navigation packages, I have to clone the source codes of the related packages in another directory (usually in the catkin workspace), and make changes and build them to get new libs or executables (so there are two ros packages with the same name now), then how could I make the program use the newly built libs without copying (or installing) them to replace the old ones in the ros install directory?
Thanks for any help!