第一步 打开bashrc文件：
sudo gedit ~/.bashrc第二步 在bashrc文件末尾加入以下代码：
1 echo "ros melodic(1) or ros2 dashing(2)?" 2 read edition 3 if [ "$edition" -eq "1" ];then 4 source /opt/ros/melodic/setup.bash 5 else 6 source /opt/ros/dashing/setup.bash 7 fi
1 #source /opt/ros/melodic/setup.bash 2 #source /opt/ros/dashing/setup.bash 3 # ROS 1.0 melodic or ROS 2.0 Dashing 4 echo ROS 1.0 or ROS 2.0? 1=Melodic 2=Dashing 5 read ROS 6 if (($ROS==1));then 7 source /opt/ros/melodic/setup.bash 8 echo "Melodic" 9 elif (($ROS==2));then 10 source /opt/ros/dashing/setup.bash 11 echo "Dashing" 12 else 13 echo "Non-ROS" 14 fi
https://zhuanlan.zhihu.com/p/145606586