One-liner to find path to ROS stack or package

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I was wondering if there was a clean way to find the path to a given ROS stack or package from the command line on Hydro, whether it is installed or just in the ROS_PACKAGE_PATH, i.e. what is probably used by roscd or roslaunch with the $(find ros_stack) arguments.

If I try to find an uninstalled ROS stack with rospack find ros_stack, it fails, whereas rosstack find ros_stack succeeds. For now I use this trick which works for both packages and stacks, whether they are installed or just present in ROS_PACKAGE_PATH:

$ ros_stack_path=`roscd ros_stack && pwd && cd - &>/dev/null`

Is there a better one-liner for this?

I also noticed something surprising. If I try both rospack and rosstack on a metapackage (e.g. navigation):

$ rospack  find navigation             ---> fails
$ rosstack find navigation             ---> succeeds

Is that the expected behavior?