Ubuntu18.04安装ROS(melodic)教程

ROS官方教程 http://wiki.ros.org/melodic/Installation/Ubuntu

添加源：

sudo sh -c ‘echo “deb http://packages.ros.org/ros/ubuntu $(lsb_release -sc) main” > /etc/apt/sources.list.d/ros-latest.list’

添加key:

sudo apt install curl
curl -s https://raw.githubusercontent.com/ros/rosdistro/master/ros.asc | sudo apt-key add -

安装：
sudo apt update
sudo apt install ros-melodic-desktop-full
apt search ros-melodic #也可不执行这一步

环境配置：
echo “source /opt/ros/melodic/setup.bash” >> ~/.bashrc
echo “source ~/catkin_ws/devel/setup.bash” >> ~/.bashrc #可不执行
source ~/.bashrc

安装rosinstall：
sudo apt install python-rosdep python-rosinstall python-rosinstall-generator python-wstool build-essential
sudo apt install python-rosdep

sudo rosdep init
rosdep update

在执行curl -s
https://raw.githubusercontent.com/ros/rosdistro/master/ros.asc | sudo apt-key add - 可能会出错。在出错的情况下我们可以离线下载证书ros.asc（网上很多下载方式），通过sudo apt-key add ros.asc 来完成加载。

后续安装步骤按照官网教程安装即可。

若出现无法rosdep init和update的错误，按如下方法解决：
（1）手动下载rosdistro-master.zip 并将文件解压到/data目录下
unzip -o rosdistro-master.zip -d /data/
（2）依次执行脚本：
sudo apt update
sudo apt install python-rosdep python-rosinstall python-rosinstall-generator python-wstool build-essential
sudo apt install python-rosdep

    sudo mkdir -p /etc/ros/rosdep/sources.list.d/

    str=/data/rosdistro-master
    cd /etc/ros/rosdep/sources.list.d/
    sudo echo "yaml file://$str/rosdep/osx-homebrew.yaml osx"  >> 20-default.list
    sudo echo "yaml file://$str/rosdep/base.yaml"  >> 20-default.list
    sudo echo "yaml file://$str/rosdep/python.yaml"  >> 20-default.list
    sudo echo "yaml file://$str/rosdep/ruby.yaml"  >> 20-default.list
    sudo echo "gbpdistro file://$str/releases/fuerte.yaml fuerte"  >> 20-default.list
    # 上面是rosdep init的步骤
    
    sudo sed -i "72a DEFAULT_SOURCES_LIST_URL = 'file://$str/rosdep/sources.list.d/20-default.list'" /usr/lib/python2.7/dist-packages/rosdep2/sources_list.py
    sudo sed -i "39a REP3_TARGETS_URL = 'file://$str/releases/targets.yaml'" /usr/lib/python2.7/dist-packages/rosdep2/rep3.py
    sudo sed -i "68a DEFAULT_INDEX_URL = 'file://$str/index-v4.yaml'"  /usr/lib/python2.7/dist-packages/rosdistro/__init__.py
    
    sudo rosdep init
    rosdep update

测试ros是否安装成功
打开三个终端：
roscore
rosrun turtlesim turtlesim_node
rosrun turtlesim turtle_teleop_key