看懂roslunch输出

自编了一个demo

第一步：创建功能包

cd ~/catkin_ws/src
catkin_create_pkg param_demo roscpp

第二步：写 main.cpp

创建文件：param_demo/src/param_node.cpp

#include <ros/ros.h>
#include <string>int main(int argc, char** argv) {ros::init(argc, argv, "param_node");ros::NodeHandle nh;std::string robot_name;int robot_id;bool use_sim;nh.param<std::string>("robot_name", robot_name, "default_bot");nh.param<int>("robot_id", robot_id, -1);nh.param<bool>("use_sim", use_sim, false);ROS_INFO_STREAM("Robot Name: " << robot_name);ROS_INFO_STREAM("Robot ID: " << robot_id);ROS_INFO_STREAM("Use Simulation: " << (use_sim ? "true" : "false"));ros::spinOnce();return 0;
}

第三步：写 config.yaml

创建文件：param_demo/config/config.yaml

robot_name: "titan"
robot_id: 42
use_sim: true

第四步：写 launch 文件

创建文件：param_demo/launch/test_param.launch

<launch><!-- 加载 YAML 配置文件 --><rosparam file="$(find param_demo)/config/config.yaml" command="load" /><!-- 启动节点 --><node pkg="param_demo" type="param_node" name="param_node" output="screen"/>
</launch>

第五步：修改 CMakeLists.txt 添加编译指令

打开 param_demo/CMakeLists.txt，找到这几行：

add_executable(param_node src/param_node.cpp)
target_link_libraries(param_node ${catkin_LIBRARIES})

第六步：编译 & 运行

cd ~/catkin_ws
catkin_make
source devel/setup.bash
roslaunch param_demo test_param.launch
输出：

~/桌面/textdemo$ roslaunch param_demo test_param.launch
... logging to /home/fengzelin/.ros/log/a949ff4a-0bd4-11f0-8c0b-591112ba82b6/roslaunch-feng-25454.log
Checking log directory for disk usage. This may take a while.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.started roslaunch server http://feng:43369/SUMMARY
========PARAMETERS* /robot_id: 42* /robot_name: titan* /rosdistro: noetic* /rosversion: 1.17.0* /use_sim: TrueNODES/param_node (param_demo/param_node)auto-starting new master
process[master]: started with pid [25462]
ROS_MASTER_URI=http://localhost:11311setting /run_id to a949ff4a-0bd4-11f0-8c0b-591112ba82b6
process[rosout-1]: started with pid [25472]
started core service [/rosout]
process[param_node-2]: started with pid [25475]
[ INFO] [1743166845.534552329]: Robot Name: titan
[ INFO] [1743166845.535322541]: Robot ID: 42
[ INFO] [1743166845.535337417]: Use Simulation: true
[param_node-2] process has finished cleanly
log file: /home/fengzelin/.ros/log/a949ff4a-0bd4-11f0-8c0b-591112ba82b6/param_node-2*.log

解释输出

... logging to /home/fengzelin/.ros/log/a949ff4a-0bd4-11f0-8c0b-591112ba82b6/roslaunch-feng-25454.log

🔹 ROS 会把启动的过程和日志写入一个日志文件
🔹 日志存在 ~/.ros/log/ 目录下，以时间戳区分

Checking log directory for disk usage. This may take a while.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

🔹 启动前会检查一下日志目录是否占用过多磁盘空间（默认设置）
🔹 这里提示：日志使用 < 1GB，问题不大 

started roslaunch server http://feng:43369/

🔹 启动了 roslaunch 的服务端（可以支持多机 ROS）
🔹 feng 是你的主机名，43369 是分配的端口号

SUMMARY 区块

PARAMETERS* /robot_id: 42* /robot_name: titan* /rosdistro: noetic* /rosversion: 1.17.0* /use_sim: True

每一项就是你在 .yaml 或 .launch 文件中设置的参数项
它们被加载到 ROS 参数服务器中了，供节点读取

NODES/param_node (param_demo/param_node)

意思是：

• 在根命名空间 / 下，启动了一个名为 param_node 的节点

• 它来自包 param_demo，可执行文件名也是 param_node

 启动核心进程信息

auto-starting new master
process[master]: started with pid [25462]

🔹 ROS master 启动了（负责协调节点通信）
🔹 PID 是 Linux 下的进程 ID（这里是 25462）

ROS_MASTER_URI=http://localhost:11311

master 的地址和端口号（本机本端口）

setting /run_id to a949ff4a-0bd4-11f0-8c0b-591112ba82b6

🔹 本次运行的唯一 ID，用于日志目录区分

process[rosout-1]: started with pid [25472]
started core service [/rosout]

🔹 rosout 是 ROS 的系统日志节点，用来收集日志信息
🔹 所有 ROS_INFO, ROS_WARN 都会发到它

process[param_node-2]: started with pid [25475]

🔹 写的 param_node 节点被启动了，进程 ID 为 25475

程序运行输出（节点打印的日志）：

[ INFO] [1743166845.534552329]: Robot Name: titan
[ INFO] [1743166845.535322541]: Robot ID: 42
[ INFO] [1743166845.535337417]: Use Simulation: true

退出

[param_node-2] process has finished cleanly
log file: /home/fengzelin/.ros/log/a949ff4a-0bd4-11f0-8c0b-591112ba82b6/param_node-2*.log