Introduction

The content of this article is only the procedure that worked for the time being.

Target application

https://qiita.com/takmot/items/987b493afeeada75925f The UDP receiver program of the above article was created with .NET Core and published for Raspberry Pi.

I have placed this application on / home / pi / work / udp / publish / udp_receiver on the Raspberry Pi. ʻUdp_receiver` is the executable file name.

SystemD Unit file

Create a SystemD Unit file on your PC. The file name should be ʻudp_receiver.service ([executable file name] .service`). The contents are as follows.

[Unit]
Description=UdpRecv
After=network.target

[Service]
User=root
Type=simple
ExecStart=/home/pi/work/udp/publish/udp_receiver

[Install]
WantedBy=multi-user.target

Description is a name and is optional. ʻExecStart` specifies the path of the program to be executed. The rest should be fine.

Auto start setting

Transfer the created SystemD Unit file to Raspberry Pi by FTP. The storage path for the SystemD Unit file will be / etc / systemd / system /. Go to sudo mv udp_receiver.service /etc/systemd/system/ etc.

After that, execute the following command. * ʻUdp_receiver` is the executable file name.

Reload the service

sudo systemctl daemon-reload

Enable automatic service startup

sudo systemctl enable udp_receiver

Below are the execution results.

1. Start service

sudo systemctl start udp_receiver

Four. Check the operating status of the service

sudo systemctl status udp_receiver

The following is the execution result of sudo systemctl status udp_receiver.

● udp_receiver.service - UdpRecv
   Loaded: loaded (/etc/systemd/system/udp_receiver.service; enabled; vendor preset: enabled)
   Active: active (running) since Wed 2020-09-23 16:33:39 JST; 5s ago
 Main PID: 1240 (udp_receiver)
    Tasks: 8 (limit: 4915)
   Memory: 5.1M
   CGroup: /system.slice/udp_receiver.service
           mq1240 /home/pi/work/udp/publish/udp_receiver

September 23 16:33:39 raspberrypi systemd[1]: Started UdpRecv.
September 23 16:33:40 raspberrypi udp_receiver[1240]: Receive wait

Five. Restart your Raspberry Pi

sudo reboot

Check if the process is automatically started after restarting

sudo ps -x

It started as follows.

Also, this time we have UDP port 8888 open, so check that as well.

sudo lsof -i:8888

Below are the results.

1. Stop the program

sudo systemctl stop udp_receiver

1. Disable autostart

sudo systemctl disable udp_receiver

Problems with auto-launching web apps

For the SystemD Unit file above The execution position of the program is "/".

In the case of a web application, there are js files and css files linked to html, If you specify them as relative paths Since the program goes to see the relative path from "/", there is no file and an error occurs. You can check for errors in this area with your browser's developer tools.

To resolve this issue, modify the SystemD Unit file as follows:

[Unit]
Description=UdpRecv
After=network.target

[Service]
User=root
Type=simple
WorkingDirectory=/home/pi/work/udp/publish		#add to
ExecStart=/home/pi/work/udp/publish/udp_receiver

[Install]
WantedBy=multi-user.target

Reference article

https://qiita.com/KEINOS/items/f3e6b3064b0cbe35fd03 https://tomosoft.jp/design/?p=11697