Add needed files

Makefile

+all: \
+	src/my_pkg \
+	set_my_ros_domain_id.sh
+
+# generates a random ROS_DOMAIN_ID for simultaneous users on a machine
+set_my_ros_domain_id.sh:
+	echo export ROS_DOMAIN_ID=$(shell seq 0 255 | shuf | head -1) > $@
+
+src/my_pkg: | tb3.py
+	ros2 pkg create my_pkg \
+		--build-type ament_python \
+		--node-name tb3 \
+	   	--destination-directory src
+	ln -srf tb3.py src/my_pkg/my_pkg/tb3.py
+	colcon build --symlink-install
+
+%/:
+	mkdir -p $@
+
+clean:
+	$(RM) -r build install log src
+	$(RM) set_my_ros_domain_id.sh

README.md

-# ros2_project
+# Turtlebot3 ROS2 template
 
+## Preparing ROS workspaces and environment variables
 
+`rosenv` alias (example in `ros.sh`) which activates preinstalled `ros-base`, `gazebo-ros-pkgs`, and `turtlebot3` workspaces. If `ros.sh` is installed in `/etc/profile.d` then `ros.sh` will be automatically loaded everytime you open a terminal. Then you can type `rosenv` to activate the ROS environment in a new terminal.
 
-## Getting started
+Setting up your `ROS_DOMAIN_ID`, e.g., if multiple users are working on the same server. You can use `set_my_ros_domain_id.sh` for this. Generate a random id with `make set_my_ros_domain_id.sh`
 
-To make it easy for you to get started with GitLab, here's a list of recommended next steps.
+# Setup
 
-Already a pro? Just edit this README.md and make it your own. Want to make it easy? [Use the template at the bottom](#editing-this-readme)!
+Open three terminal windows for:
 
-## Add your files
+1. running your ROS node
+2. writing code
+3. launching & monitoring Gazebo
 
-- [ ] [Create](https://docs.gitlab.com/ee/user/project/repository/web_editor.html#create-a-file) or [upload](https://docs.gitlab.com/ee/user/project/repository/web_editor.html#upload-a-file) files
-- [ ] [Add files using the command line](https://docs.gitlab.com/ee/gitlab-basics/add-file.html#add-a-file-using-the-command-line) or push an existing Git repository with the following command:
+### 1st window - running your ROS node
 
-```
-cd existing_repo
-git remote add origin https://mygit.th-deg.de/ps16214/ros2_project.git
-git branch -M main
-git push -uf origin main
-```
-
-## Integrate with your tools
-
-- [ ] [Set up project integrations](https://mygit.th-deg.de/ps16214/ros2_project/-/settings/integrations)
-
-## Collaborate with your team
 
-- [ ] [Invite team members and collaborators](https://docs.gitlab.com/ee/user/project/members/)
-- [ ] [Create a new merge request](https://docs.gitlab.com/ee/user/project/merge_requests/creating_merge_requests.html)
-- [ ] [Automatically close issues from merge requests](https://docs.gitlab.com/ee/user/project/issues/managing_issues.html#closing-issues-automatically)
-- [ ] [Enable merge request approvals](https://docs.gitlab.com/ee/user/project/merge_requests/approvals/)
-- [ ] [Automatically merge when pipeline succeeds](https://docs.gitlab.com/ee/user/project/merge_requests/merge_when_pipeline_succeeds.html)
-
-## Test and Deploy
-
-Use the built-in continuous integration in GitLab.
-
-- [ ] [Get started with GitLab CI/CD](https://docs.gitlab.com/ee/ci/quick_start/index.html)
-- [ ] [Analyze your code for known vulnerabilities with Static Application Security Testing(SAST)](https://docs.gitlab.com/ee/user/application_security/sast/)
-- [ ] [Deploy to Kubernetes, Amazon EC2, or Amazon ECS using Auto Deploy](https://docs.gitlab.com/ee/topics/autodevops/requirements.html)
-- [ ] [Use pull-based deployments for improved Kubernetes management](https://docs.gitlab.com/ee/user/clusters/agent/)
-- [ ] [Set up protected environments](https://docs.gitlab.com/ee/ci/environments/protected_environments.html)
+```sh
+git clone https://mygit.th-deg.de/gaydos/tb3-ros2-template && cd tb3-ros2-template 
+make  # creates a ROS package, builds it and links `tb3.py` to the file in `src/.../tb3.py` (creates a shortcut)
+. ./set_my_ros_domain_id.sh  # sets a random `ROS_DOMAIN_ID`. Useful when multiple users are working on the same server
+. ./install/local_setup.sh  # activate current workspace (you can also use `. ./load_workspace.sh`)
+```
 
-***
+Then you can run your ROS node:
+```sh
+ros2 run my_pkg tb3  # (you can also use `./run.sh`)
+```
 
-# Editing this README
+This should at least output:
+```
+waiting for messages...
+```
 
-When you're ready to make this README your own, just edit this file and use the handy template below (or feel free to structure it however you want - this is just a starting point!).  Thank you to [makeareadme.com](https://www.makeareadme.com/) for this template.
+If the robot is already brought up, then you should also get `LaserScan` messages:
+```
+F: 0.5624107122421265
+R: 0.3894226849079132
+...
+```
 
-## Suggestions for a good README
-Every project is different, so consider which of these sections apply to yours. The sections used in the template are suggestions for most open source projects. Also keep in mind that while a README can be too long and detailed, too long is better than too short. If you think your README is too long, consider utilizing another form of documentation rather than cutting out information.
+### 2nd window - writing code
 
-## Name
-Choose a self-explaining name for your project.
+Open `tb3.py` with your your favorite text editor, e.g., `vim`, `Visual Studio Code (Code OSS)`
 
-## Description
-Let people know what your project can do specifically. Provide context and add a link to any reference visitors might be unfamiliar with. A list of Features or a Background subsection can also be added here. If there are alternatives to your project, this is a good place to list differentiating factors.
+### 3rd window - launching & monitoring Gazebo
 
-## Badges
-On some READMEs, you may see small images that convey metadata, such as whether or not all the tests are passing for the project. You can use Shields to add some to your README. Many services also have instructions for adding a badge.
+```sh
+rosenv
+gazebo --verbose WORLD_FILE  # the world file can be e.g., world.sdf
+```
 
-## Visuals
-Depending on what you are making, it can be a good idea to include screenshots or even a video (you'll frequently see GIFs rather than actual videos). Tools like ttygif can help, but check out Asciinema for a more sophisticated method.
+Should output:
+```
+Gazebo multi-robot simulator, ...
+...
+[Msg] Waiting for master.
+[Msg] Connected to gazebo master @ http://127.0.0.1:11345
+...
+[Msg] Loading world file [/home/...]
+...
+```
 
-## Installation
-Within a particular ecosystem, there may be a common way of installing things, such as using Yarn, NuGet, or Homebrew. However, consider the possibility that whoever is reading your README is a novice and would like more guidance. Listing specific steps helps remove ambiguity and gets people to using your project as quickly as possible. If it only runs in a specific context like a particular programming language version or operating system or has dependencies that have to be installed manually, also add a Requirements subsection.
+And if you open a world with TB3 or add it manually:
+```
+[INFO] [1608802634.071946263] [gazebo_ros_node]: ROS was initialized without arguments.
+...
+```
 
-## Usage
-Use examples liberally, and show the expected output if you can. It's helpful to have inline the smallest example of usage that you can demonstrate, while providing links to more sophisticated examples if they are too long to reasonably include in the README.
+After TB3 is instantiated, you should see `LaserScan` values in the first window
 
-## Support
-Tell people where they can go to for help. It can be any combination of an issue tracker, a chat room, an email address, etc.
 
-## Roadmap
-If you have ideas for releases in the future, it is a good idea to list them in the README.
+## Notes
 
-## Contributing
-State if you are open to contributions and what your requirements are for accepting them.
+- In Gazebo, use CTRL+r on Gazebo to restart the simulation. This way you do not have to close and open Gazebo
+- use CTRL+C to kill a command line process, e.g., your ROS program or non-responsive Gazebo
+- if you get the following error:
 
-For people who want to make changes to your project, it's helpful to have some documentation on how to get started. Perhaps there is a script that they should run or some environment variables that they need to set. Make these steps explicit. These instructions could also be useful to your future self.
+  ```
+  [Err] ... EXCEPTION: Unable to start server[bind: Address already in use]. There is probably another Gazebo process running.
+  ```
 
-You can also document commands to lint the code or run tests. These steps help to ensure high code quality and reduce the likelihood that the changes inadvertently break something. Having instructions for running tests is especially helpful if it requires external setup, such as starting a Selenium server for testing in a browser.
+  then choose another port for Gazebo, e.g.:
 
-## Authors and acknowledgment
-Show your appreciation to those who have contributed to the project.
+  ```
+  $ GAZEBO_MASTER_URI=:12346 gazebo --verbose challenge_2.sdf
+  ```
 
-## License
-For open source projects, say how it is licensed.
+- if you do not use the simulation, then close Gazebo to leave the processor resources for others. If the system is slow, `htop` may show you the reason. `htop` shows who the active processes belong to and processor usage.
+- you can kill a process with process id 12345 using `kill 12345`. The process id is shown in the `PID` column in `htop`.
+- `make clean` removes all generated files which may help in case of an error
+- `tools/` folder contain convenience scripts, e.g.,
 
-## Project status
-If you have run out of energy or time for your project, put a note at the top of the README saying that development has slowed down or stopped completely. Someone may choose to fork your project or volunteer to step in as a maintainer or owner, allowing your project to keep going. You can also make an explicit request for maintainers.
+  - `stop-tb3.sh`: to stop the robot manually
+  - `tb3-teleop.sh`: teleoperation using keyboard

build/.built_by

+colcon

build/my_pkg/colcon_build.rc

+0

build/my_pkg/colcon_command_prefix_setup_py.sh

+# generated from colcon_core/shell/template/command_prefix.sh.em

build/my_pkg/colcon_command_prefix_setup_py.sh.env

+AMENT_PREFIX_PATH=/home/ps16214/py_pubsub/install/py_pubsub:/opt/ros/galactic-turtlebot3-quickstart:/opt/ros/galactic
+CMAKE_PREFIX_PATH=/opt/ros/galactic-turtlebot3-quickstart:/opt/ros/galactic
+COLCON=1
+COLCON_PREFIX_PATH=/home/ps16214/py_pubsub/install:/opt/ros/galactic-turtlebot3-quickstart:/opt/ros/galactic
+CONDA_EXE=/usr/bin/conda
+CONDA_SHLVL=0
+CUDA_PATH=/opt/cuda
+CYCLONEDDS_URI=/share/cyclonedds-profile.xml
+DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/36945/bus
+DISPLAY=localhost:25.0
+GAZEBO_MASTER_URI=http://localhost:11345
+GAZEBO_MODEL_DATABASE_URI=http://models.gazebosim.org
+GAZEBO_MODEL_PATH=/usr/share/gazebo-11/models:/opt/ros/galactic/../galactic-turtlebot3-quickstart/share/turtlebot3_gazebo/models:
+GAZEBO_PLUGIN_PATH=/usr/lib/gazebo-11/plugins:/opt/ros/galactic/../galactic-turtlebot3-quickstart/lib:
+GAZEBO_RESOURCE_PATH=/usr/share/gazebo-11:/opt/ros/galactic/../galactic-turtlebot3-quickstart/share/turtlebot3_gazebo/worlds:
+HG=/usr/bin/hg
+HOME=/home/ps16214
+LANG=en_US.UTF-8
+LD_LIBRARY_PATH=/usr/lib/gazebo-11/plugins:/opt/ros/galactic-turtlebot3-quickstart/lib:/opt/ros/galactic/opt/yaml_cpp_vendor/lib:/opt/ros/galactic/opt/rviz_ogre_vendor/lib:/opt/ros/galactic/lib:/usr/lib/gazebo-11/plugins:
+LOGNAME=ps16214
+MAIL=/var/spool/mail/ps16214
+MAKEFLAGS=
+MAKELEVEL=1
+MAKE_TERMERR=/dev/pts/21
+MAKE_TERMOUT=/dev/pts/21
+MFLAGS=
+MKLROOT=/opt/intel/mkl
+MOTD_SHOWN=pam
+OGRE_RESOURCE_PATH=/usr/lib/OGRE
+OLDPWD=/home/ps16214
+PATH=/opt/ros/galactic-turtlebot3-quickstart/bin:/opt/ros/galactic/bin:/usr/condabin:/usr/local/sbin:/usr/local/bin:/usr/bin:/opt/cuda/bin:/opt/cuda/nsight_compute:/opt/cuda/nsight_systems/bin:/usr/lib/jvm/default/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/home/share/
+PKG_CONFIG_PATH=/opt/ros/galactic-turtlebot3-quickstart/lib/pkgconfig:/opt/ros/galactic/lib/pkgconfig
+PWD=/home/ps16214/tb3-ros2-template/build/my_pkg
+PYTHONPATH=/home/ps16214/py_pubsub/install/py_pubsub/lib/python3.10/site-packages:/opt/ros/galactic-turtlebot3-quickstart/lib/python3.10/site-packages:/opt/ros/galactic/lib/python3.10/site-packages
+ROS_DISTRO=galactic
+ROS_DOMAIN_ID=55
+ROS_LOCALHOST_ONLY=0
+ROS_PYTHON_VERSION=3
+ROS_VERSION=2
+SHELL=/bin/bash
+SHLVL=1
+SSH_CLIENT=10.1.65.86 34906 22
+SSH_CONNECTION=10.1.65.86 34906 195.37.232.77 22
+SSH_TTY=/dev/pts/21
+TERM=xterm-256color
+TURTLEBOT3_MODEL=waffle_pi
+USER=ps16214
+XDG_RUNTIME_DIR=/run/user/36945
+XDG_SESSION_CLASS=user
+XDG_SESSION_ID=182
+XDG_SESSION_TYPE=tty
+_=/usr/bin/env

build/my_pkg/my_pkg

+/home/ps16214/tb3-ros2-template/src/my_pkg/my_pkg
\ No newline at end of file

build/my_pkg/my_pkg.egg-info/PKG-INFO

+Metadata-Version: 2.1
+Name: my-pkg
+Version: 0.0.0
+Summary: TODO: Package description
+Home-page: UNKNOWN
+Maintainer: ps16214
+Maintainer-email: ps16214@todo.todo
+License: TODO: License declaration
+Platform: UNKNOWN
+
+UNKNOWN
+

build/my_pkg/my_pkg.egg-info/SOURCES.txt

+package.xml
+setup.cfg
+setup.py
+my_pkg/__init__.py
+my_pkg/tb3.py
+my_pkg.egg-info/PKG-INFO
+my_pkg.egg-info/SOURCES.txt
+my_pkg.egg-info/dependency_links.txt
+my_pkg.egg-info/entry_points.txt
+my_pkg.egg-info/requires.txt
+my_pkg.egg-info/top_level.txt
+my_pkg.egg-info/zip-safe
+resource/my_pkg
\ No newline at end of file

build/my_pkg/my_pkg.egg-info/dependency_links.txt

+

build/my_pkg/my_pkg.egg-info/entry_points.txt

+[console_scripts]
+tb3 = my_pkg.tb3:main
+

build/my_pkg/my_pkg.egg-info/requires.txt

+setuptools

build/my_pkg/my_pkg.egg-info/top_level.txt

+my_pkg

build/my_pkg/my_pkg.egg-info/zip-safe

+

build/my_pkg/package.xml

+/home/ps16214/tb3-ros2-template/src/my_pkg/package.xml
\ No newline at end of file

build/my_pkg/resource/my_pkg

+/home/ps16214/tb3-ros2-template/src/my_pkg/resource/my_pkg
\ No newline at end of file

build/my_pkg/setup.cfg

+/home/ps16214/tb3-ros2-template/src/my_pkg/setup.cfg
\ No newline at end of file

build/my_pkg/setup.py

+/home/ps16214/tb3-ros2-template/src/my_pkg/setup.py
\ No newline at end of file

build/my_pkg/share/my_pkg/hook/pythonpath_develop.dsv

+prepend-non-duplicate;PYTHONPATH;/home/ps16214/tb3-ros2-template/build/my_pkg