vscode

// How do I duplicate a line or selection within Visual Studio Code?
File > Preferences > Keyboard Shortcuts. And editing the keybindings.json
[
  {
    "key": "ctrl+d",
    "command": "editor.action.copyLinesDownAction",
    "when": "editorTextFocus"
  },
  {
    "key": "ctrl+shift+u",
    "command": "editor.action.transformToUppercase",
    "when": "editorTextFocus"
  },
  {
    "key": "ctrl+shift+l",
    "command": "editor.action.transformToLowercase",
    "when": "editorTextFocus"
  }
]