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Managing System dependenciesDescription: This explains how to use rosdep to install system dependencies.
Tutorial Level: INTERMEDIATE
Next Tutorial: Roslaunch tips for large projects
ROS packages sometimes require external libraries and tools that must be provided by the operating system. These required libraries and tools are commonly referred to as system dependencies. In some cases these system dependencies are not installed by default. ROS provides a simple tool, rosdep, that is used to download and install system dependencies.
ROS packages must declare that they need these system dependencies in the package manifest. Let's look at the manifest for the turtlesim package:
$ roscd turtlesim
$ cat package.xml
<package> ... ... <build_depend>message_generation</build_depend> <build_depend>libqt4-dev</build_depend> <build_depend>qt4-qmake</build_depend> <build_depend>rosconsole</build_depend> <build_depend>roscpp</build_depend> <build_depend>roscpp_serialization</build_depend> <build_depend>roslib</build_depend> <build_depend>rostime</build_depend> <build_depend>std_msgs</build_depend> <build_depend>std_srvs</build_depend> </package>
As you can see turtlesim needs those libraries and packages.
$ cat manifest.xml
<package> ... ... <rosdep name="libqt4-dev"/> <rosdep name="qt4-qmake"/> </package>
As you can see turtlesim needs libqt4-dev and qt4-qmake.
rosdep is a tool you can use to install system dependencies required by ROS packages.
rosdep install [package]
Download and install the system dependencies for turtlesim:
$ rosdep install turtlesim
If you've been following along with the tutorials, it's likely that this is the first time you've used rosdep. When you run this command, you'll get an error message:
ERROR: your rosdep installation has not been initialized yet. Please run: sudo rosdep init rosdep update
Just run those two commands and then try to install turtlesim's dependencies again.
If you installed using binaries you will see:
All required rosdeps installed successfully
Otherwise you will see the output of installing the dependencies of turtlesim:
#!/usr/bin/bash set -o errexit set -o verbose if [ ! -f /opt/ros/lib/libboost_date_time-gcc42-mt*-1_37.a ] ; then mkdir -p ~/ros/ros-deps cd ~/ros/ros-deps wget --tries=10 http://pr.willowgarage.com/downloads/boost_1_37_0.tar.gz tar xzf boost_1_37_0.tar.gz cd boost_1_37_0 ./configure --prefix=/opt/ros make sudo make install fi if [ ! -f /opt/ros/lib/liblog4cxx.so.10 ] ; then mkdir -p ~/ros/ros-deps cd ~/ros/ros-deps wget --tries=10 http://pr.willowgarage.com/downloads/apache-log4cxx-0.10.0-wg_patched.tar.gz tar xzf apache-log4cxx-0.10.0-wg_patched.tar.gz cd apache-log4cxx-0.10.0 ./configure --prefix=/opt/ros make sudo make install fi
rosdep runs the bash script above and exits when complete.
$ rosdep update
rosdep actually retrieves the rules from the rosdistro github repository.
These rules are used when a dependency is listed that doesn't match the name of a ROS package built on the buildfarm. Then rosdep checks if there exists a rule to resolve it for the proper platform and package manager you are using.
When creating a new package, you might need to declare new system dependencies to the rosdep rules if there are not there yet. Just edit the file, add the dependency needed (following a strict alphabetical order and a similar structure as the other dependencies already registered) and send a pull request.
After that pull request has been merged, you need to run :
$ rosdep update
and now that dependency will be resolved by rosdep.
You can test it with :
$ rosdep resolve my_dependency_name
The output should be something like :
where the first line is the package manager chosen for installing this dependency, and the second line is the actual name for that dependency on your current platform.