# Install several packages at once

If you want to install from source different packages, using `catkin_make_isolated` without re-compiling existing packages (that are downloaded since they're dependencies) you can follow this:

Prepare you workspace
    mkdir my_wksp
    cd my_wksp

Generate the packages list
    rosinstall_generator stack1 packageb blabla --rosdistro hydro --wet-only --deps --exclude RPP > all.rosinstall

Download the packages, update the workspace
    wstool init -j8 src all.rosinstall
    # or, if you're working with an existing workspace
    # wstool merge all.rosinstall -t src
    # wstool update -j8 -t src

Install system dependencies
    rosdep install --from-paths src --ignore-src --rosdistro hydro -y -r 
    # Add "--os=debian:wheezy" if you need (not needed on ubuntu, might be needed on debian)

Compile
    catkin_make_isolated -q --merge --install-space /opt/ros/hydro/

Install !
    sudo /opt/ros/hydro/env.sh catkin_make_isolated --install --install-space /opt/ros/hydro/ -q --merge

That should be it. If you compare to the other examples (Debian install, Turtlebot install), you might notice some changes:

* `--exclude RPP` is used to exclude the already installed packages from the dependencies search
* Two lines for catkin_make_isolated instead of one: That's because compiling as root is bad