rosdep is a command-line tool for installing system dependencies

rosdep uses the backend of operating system for installing
packages. For end-users, rosdep helps you install system dependencies
for software that you are building from source. For developers, rosdep
simplifies the problem of installing system dependencies on different
platforms.

On FreeBSD, the pkg system is used.

WWW: http://docs.ros.org/independent/api/rosdep/html/