【解决问题】RLException: [xx.launch] is neither a launch file in package [x] nor is [x] a launch file name

本博客运行环境为Ubuntu 18.04.

今天在ROS工作区下编译时遇到如下错误：
RLException: [racecar.launch] is neither a launch file in package [racecar_gazebo] nor is [racecar_gazebo] a launch file name
The traceback for the exception was written to the log file

报错才想起没有添加环境变量，一段时间没做相关应用都有点搞忘了hhh

解决方案

方案1
回去再次编译：

catkin_make

添加环境变量：

source ./devel/setup.bash

方案2
相比方案1，这个不需要每次编写都添加环境变量了。
打开这个文件：

sudo  gedit ~/.bashrc

在该文件的最后添加如下代码
catkin_ws为我的ROS工作路径。

source ~/catkin_ws/devel/setup.bash

export ROS_PACKAGE_PATH=${ROS_PACKAGE_PATH}:~/catkin_ws/

然后重启bashrc

source ~/.bashrc

查看ROS路径是否添加上

echo $ROS_PACKAGE_PATH

设置成功会显示你添加的路径。