Yes, use local_ setup. Bash or setup bash

Finished compiling ros2 After procedure , We will find that install There are two scripts in the directory local_setup.bash and setup.bash. Before executing the program , Usually source once install Scripts in directory , So that the environment variables are ready . such ros2 run and ros2 launch You can find the corresponding execution file and dependency .

The following is from setup.bash A segment taken from . It can be found that it will source once /opt/ros/galactic Catalog re source once /home/ubuntu/turtlebot3_ws/install Catalog , Finally, source Click the current directory . This will include multiple external workspaces . If there are function packages with the same name in multiple workspaces, they may conflict with each other .

# source chained prefixes
# setting COLCON_CURRENT_PREFIX avoids determining the prefix in the sourced script
COLCON_CURRENT_PREFIX="/opt/ros/galactic"
_colcon_prefix_chain_bash_source_script "$COLCON_CURRENT_PREFIX/local_setup.bash"
# setting COLCON_CURRENT_PREFIX avoids determining the prefix in the sourced script
COLCON_CURRENT_PREFIX="/home/ubuntu/turtlebot3_ws/install"
_colcon_prefix_chain_bash_source_script "$COLCON_CURRENT_PREFIX/local_setup.bash"

# source this prefix
# setting COLCON_CURRENT_PREFIX avoids determining the prefix in the sourced script
COLCON_CURRENT_PREFIX="$(builtin cd "`dirname "${
         BASH_SOURCE[0]}"`" > /dev/null && pwd)"
_colcon_prefix_chain_bash_source_script "$COLCON_CURRENT_PREFIX/local_setup.bash"

unset COLCON_CURRENT_PREFIX
unset _colcon_prefix_chain_bash_source_script

and local_setup.bash It's just source Script directory . This will only find the current install The executable files and dependencies in the directory .

So if there are multiple in the system ROS working space , A more cautious approach is ：

1、 First source once /opt/ros/galactic/local_setup.bash

2、 stay source Let's look at a user's workspace .

If there is only a self built user workspace in the system . Then directly source In the user workspace install In the catalog setup.bash. It's all done .

It will help you first source once /opt/ros/galactic/local_setup.bash, In this way, there will be systematic installation ros Execute programs and dependencies . And then help you source Of this user space install/local_setup.bash.

Reference resources ：

https://colcon.readthedocs.io/en/released/developer/environment.html#workspace-level

https://answers.ros.org/question/292566/what-is-the-difference-between-local_setupbash-and-setupbash/

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