i am unable to install ROS package directly from terminal by using the command- "sudo apt-get install package_name".everytime it gives an error: unable to locate paackage.please suggest.

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Either something was skipped during installation, or you are trying to install packages that aren't available. As far as I know the ros-jade-husky-simulator isn't released on the build farm (check Jade's distribution.yaml). If you want to use the husky_simulator package, you'll either need to be on Indigo, or build the package from source.

If none of your ROS packages are able to be installed, then something was skipped during installation. Check the output of cat /etc/apt/source.list.d/ros-latest.list ensure that the ROS package repos are added to your apt sources. Also be sure to run sudo apt-get update to download the package list.

You should use sudo apt-get install ros-<distro>-package_name, change the <distro> to the ros distro you are using. For example try: sudo apt-get install ros-indigo-urg-node

Or use a package manager Synaptic Package Manager and search for the package you want to install.

Another method is to use git and clone a package to your workspace. For example

cd your_catkin_ws/src

git clone -b indigo-devel https://github.com/ros-drivers/urg_node.git