🔸 gRPC

Build and locally install gRPC and Protocol Buffers for C++ on Ubuntu x86_64 6.8.0-49-generic

Prerequisites

• cmake 3.16 or later (https://vitux.com/how-to-install-cmake-on-ubuntu/)

1. Configures a directory for locally installed packages and ensures the executables are easily accessible from the command line
   

    ~$ export LOCAL_INSTALL_DIR=$HOME/.local
    ~$ mkdir -p $LOCAL_INSTALL_DIR
    ~$ export PATH="$LOCAL_INSTALL_DIR/bin:$PATH"

2. Install the basic tools required to build gRPC

   ~$ sudo apt install -y build-essential autoconf libtool pkg-config

3. Clone the grpc repo and its submodules

   ~$ git clone --recurse-submodules -b v1.66.0 --depth 1 --shallow-submodules https://github.com/grpc/grpc

4. Build and locally install gRPC and Protocol Buffers

   ~$ cd grpc
   ~/grpc$ mkdir -p cmake/build
   ~/grpc$ pushd cmake/build
   ~grpc/cmake/build$ cmake -DgRPC_INSTALL=ON \
                            -DgRPC_BUILD_TESTS=OFF \
                            -DCMAKE_INSTALL_PREFIX=$LOCAL_INSTALL_DIR \
                            ../..
   ~grpc/cmake/build$ make -j 4
   ~grpc/cmake/build$ make install
   ~grpc/cmake/build$ popd

5. Build the project
   in ~/grpc/examples/protos/ save .proto file
   in ~/grpc/examples/cpp/ create new directory myproject containing source .cc code and CMakeLists.txt
   

   ~/grpc$ cd examples/cpp/myproject
   ~/grpc/examples/cpp/myproject$ mkdir -p cmake/build
   ~/grpc/examples/cpp/myproject$ pushd cmake/build
   ~/grpc/examples/cpp/myproject/cmake/build$ cmake -DCMAKE_PREFIX_PATH=$LOCAL_INSTALL_DIR ../..
   ~/grpc/examples/cpp/myproject/cmake/build$ make -j 4

6. Run the project from the project build directory
   

   ~/grpc/examples/cpp/myproject/cmake/build$ ./app
   

Build and locally install gRPC and Protocol Buffers for Python on Ubuntu x86_64 6.8.0-49-generic

Prerequisites

• Python 3.7 or higher
• pip version 9.0.1 or higher

1. Install gRPC

   ~$ python3 -m pip install grpcio

2. Install gRPC tools

   ~$ python3 -m pip install grpcio-tools

3. Build the project
   create new directory myproject containing .proto file and source .py code
   
4. Run the project
   from project directory myproject in terminal run python3 app.py

🔸 From Python script to Linux service using systemd

A daemon (or service) is a background process that is designed to run autonomously,with little or not user intervention. Services will start automatically every time the system starts, which eliminates the need to start it manually. Scripts that collect data, represent servers or similar are ideal candidates to be configured as services and not ordinary scripts.

1. Write Python script you want to make as service /path/to/your_script.py
2. Make your Python script executable

   ~$ chmod +x /path/to/your_script.py

3. Create systemd service file in directory /etc/systemd/system/. Systemd service files need to be in /etc/systemd/system/ DIR!

   ~$ sudo nano /etc/systemd/system/your_script.service

4. Add following content to your .service file

   [Unit]
   Description=Python Script Service
   After=network.target
   
   [Service]
   ExecStart=/usr/bin/python3 /path/to/your_script.py
   Restart=always
   User=your_user
   WorkingDirectory=/path/to/
   Environment="PATH=/usr/bin"
   
   [Install]
   WantedBy=multi-user.target
   

5. Reload systemd to recognise new service your_script.service

   sudo systemctl daemon-reload

6. Enable new service at system startup

   sudo systemctl enable your_script.service

7. Run service

   sudo systemctl start your_script.service

8. Managing the service
   • stop service

     sudo systemctl stop your_script.service

   • restart service

     sudo systemctl stop your_script.service

   • disable service at system startup

     sudo systemctl disable your_script.service
     
     

🔸 Natively build a Linux kernel on RPi 3B

Complete quidance on : https://www.raspberrypi.com/documentation/computers/linux_kernel.html#install-directly-onto-the-sd-card.
This guide assumes that your Raspberry Pi runs the latest version of Raspberry Pi OS.
sudo apt install git
git clone --depth=1 https://github.com/raspberrypi/linux

1. Install the build dependencies
   sudo apt install bc bison flex libssl-dev make
2. Build configuration
   In this case, Im using RPi3B and for 32bit distribution run following commands

   cd linux
   KERNEL=kernel7
   make bcm2709_defconfig

3. Build the 32-bit kernel (this step will take A LONG TIME -couple of hours)
   make -j6 zImage modules dtbs
4. Install the kernel modules onto the boot media
   sudo make -j6 modules_install
5. Create a backup of your current kernel and install the fresh kernel image

   sudo cp /boot/firmware/$KERNEL.img /boot/firmware/$KERNEL-backup.img
   sudo cp arch/arm/boot/zImage /boot/firmware/$KERNEL.img

6. For kernels version 6.5 and above
   sudo cp arch/arm/boot/dts/broadcom/*.dtb /boot/firmware/
7. Copy over the overlays and README

   sudo cp arch/arm/boot/dts/overlays/*.dtb* /boot/firmware/overlays/
   sudo cp arch/arm/boot/dts/overlays/README /boot/firmware/overlays/

8. Finally, run the following command to reboot your Raspberry Pi and run your freshly-compiled kernel sudo reboot