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No stdout logging output in ROS2 using launch

asked 2019-09-11 13:48:53 -0500

jdlangs gravatar image

Hi all,

I am unable to see any logging output from stdout when using ros2 launch, and I need some help figuring out what's going on / if this is expected. For example this cpp file:

int main(int argc, char** argv)
  rclcpp::init(argc, argv);
  auto node = std::make_shared<rclcpp::Node>("a_test_node");

  RCLCPP_DEBUG(node->get_logger(), "test log debug");
  RCLCPP_INFO(node->get_logger(), "test log info");
  RCLCPP_WARN(node->get_logger(), "test log warn");
  RCLCPP_ERROR(node->get_logger(), "test log error");


  return 0;

and this launch file:

import launch
import launch_ros.actions

def generate_launch_description():
    return launch.LaunchDescription([
                'stdout': 'screen',
                'stderr': 'screen',

only outputs:

jlangsfeld@swri-jlangsfeld-thinkpad-T560:~/Workspaces/ros2$ ros2 launch test_pkg
[INFO] [launch]: All log files can be found below /home/jlangsfeld/.ros/log/2019-09-11-13-45-19-657412-swri-jlangsfeld-thinkpad-T560-18153
[INFO] [launch]: Default logging verbosity is set to INFO
[INFO] [test_node-1]: process started with pid [18163]
[test_node-1] [WARN] [test_node]: test log warn
[test_node-1] [ERROR] [test_node]: test log error

I've tried other output options too with no luck. For example, using own_log for both stdout and stderr means separate log files are created but the stdout one always is completely empty. Any thoughts / suggestions?

Thanks, Josh

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can you try output="screen" without the json? That's what I usually do


I see the warn and error, but not info, perhaps because you didnt set to screen in general

stevemacenski gravatar imagestevemacenski ( 2019-09-11 15:04:50 -0500 )edit

Yes, I've tried the single string, which should just be a shortcut for setting both stdout and stderr directly. Are you saying you don't see info outputs either when you run launch files?

jdlangs gravatar imagejdlangs ( 2019-09-11 15:20:48 -0500 )edit

No, I do see them with just the simple string

stevemacenski gravatar imagestevemacenski ( 2019-09-11 15:28:04 -0500 )edit

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answered 2019-09-13 16:22:08 -0500

jacobperron gravatar image

With your example, I do see the INFO output, but it comes after terminating the program (e.g SIGINT):

[INFO] [launch]: Default logging verbosity is set to INFO
[INFO] [test_node-1]: process started with pid [18943]
[test_node-1] [WARN] [test_node]: test log warn
[test_node-1] [ERROR] [test_node]: test log error
^C[WARNING] [launch]: user interrupted with ctrl-c (SIGINT)
[test_node-1] [INFO] [test_node]: test log info

It's possible there's some buffer funny-business happening in launch. It might be worth opening a issue describing the problem.

I wouldn't expect you to be able to see the DEBUG log, without setting the verbosity level accordingly.

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I never noticed but the same thing is happening for me too. I'll go ahead and open an issue then.

jdlangs gravatar imagejdlangs ( 2019-09-13 16:53:30 -0500 )edit

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Asked: 2019-09-11 13:48:53 -0500

Seen: 20 times

Last updated: 2 days ago