#include <iostream>
using namespace std;

int main()
{
    while(1)
    {
        std::string s;
        std::cin >> s;
        std::cout << "Hello world " + s + "\n";
    }
}

sudo systemctl stop helloworld.service
sudo systemctl start helloworld.service
sudo systemctl status helloworld.service


(file name=helloworld.service path to put this file in is /lib/systemd/system)
[Unit]
Description=HelloWorld demo service
After=network.target
StartLimitIntervalSec=0

[Service]
Type=simple
Restart=always
RestartSec=1
User=root
ExecStart=/home/murtaza/99X/C++/HelloWorld/main

[Install]
WantedBy=multi-user.target