Zubashev Stepan's blog

How to make a simple system.d service for a node.js server

Put this content:

[Unit]
Description={name}

[Service]
Type=simple
User={user}
ExecStart=/usr/bin/node {full-path-to-script}.js

[Install]
WantedBy=multi-user.target

… somewhere as {name}.service, where:

  • {name} is the name of the service
  • {user} is the name of the user to run the script (optional)

… then:

  • run: this sudo ln -s /{full_path}/{name}.service /lib/systemd/system/{name}.service 
  • then this: sudo systemctl daemon-reload
  • then this: sudo systemctl enable {name}.service
  • and finally this: sudo systemctl start {name}

How does it work?

  • It starts the service on boot (see WantedBy section).
  • Using ExecStart command. Important: we specify the full path to node
  • SystemD remembers the PID of the new process and considers the service is ongoing until the process is died.
  • So any subsequent systemctrl start {name} won’t do anything if the previous process is alive.
  • This behavior is determined by Type=Simple

Multilayout Keybinds in a Browser

Imagine that you want to add support of some keybinds in your web application. Let it be Ctrl+L for liking\unliking something. What kind of issues can you face in such a scenario?

CMD or Ctrl?

At first look at Ctrl. Probably on MacOS you’d like to replace it with CMD.  You can check it by event.metaKey.

Extra modificators

Probably you wouldn’t like to consider Ctrl+Alt+S as Ctrl+S. So don’t forget to handle this case.

Different layouts

Not every language that uses the Latin alphabet has the L button at the same position as in a typical English keyboard layout. You need to decide what is more important to you ― a real key position on a keyboard or a letter upon of it. I’d guess that the 2nd case is preferable for most applications. 

To get a real key position you can use which, code, codeKey properties. To get a letter on the key use key property.

Different alphabets

What’s about Greek or Russian alphabets? Or any other possible alphabets? Or not even alphabets? There’re different strategies. And one of them is to use a key from a typical English keyboard layout. So it leads us again to code and codeKey properties.

Example

const getEventKeyBind = event => {
  const keybind = [];

  if (event.metaKey) keybind.push('cmd');
  if (event.ctrlKey) keybind.push('ctrl');
  if (event.shiftKey) keybind.push('shift');
  if (event.altKey) keybind.push('alt');

  if (event.key === ' ') keybind.push('space');
  else {
    const key = event.key.toLowerCase();

    if (key.length !== 1 || key.match(/^[a-z]$/)) {
      // latin key or a special key
      keybind.push(key);
    } else {
      // extra-latin or non-latin key
      const [, enSymbol] = event.code.match(/^Key(\w)$/) || [];
      keybind.push(enSymbol ? enSymbol.toLowerCase() : key);
    }
  }

  return keybind.join('+');
};

Custom English-German layout for Ubuntu

German language contains some extra latin symbols that English language doesn’t: ä, ö, ü, ß. But if you choose German keyboard layout instead of English you get some keyboard keys moved to unusual positions. If it’s okay for you then you don’t need to do anything with it. Just get used to the new layout! But if you wanna stay with the English version of latin keys positions you need to find some convenient way to type German specific letters.

Under the cut 3 ways to handle it:

  • Compose key
  • International layout with "dead keys"
  • Write your own EN-layout
Read more