asdf を使って Flutter をインストールする手順について

# インストール手順

前提: `asdf` がインストールされていること

```sh
$ asdf plugin-add flutter
$ asdf install flutter 2.8.1-stable
$ asdf global flutter 2.8.1-stable
```

*記事投稿時の 2022/01/27 時点では 2.8.1 が最新安定版でした

# 確認手順

インストールが成功しているかどうかを確認するために、
`Flutter` のバージョンを確認しておきます。

以下のように `Flutter` のバージョンが出力されれば ok です。

```sh
$ flutter --version               
Flutter 2.8.1 • channel stable • https://github.com/flutter/flutter.git
Framework • revision 77d935af4d (6 weeks ago) • 2021-12-16 08:37:33 -0800
Engine • revision 890a5fca2e
Tools • Dart 2.15.1

  ╔════════════════════════════════════════════════════════════════════════════╗
  ║                 Welcome to Flutter! - https://flutter.dev                  ║
  ║                                                                            ║
  ║ The Flutter tool uses Google Analytics to anonymously report feature usage ║
  ║ statistics and basic crash reports. This data is used to help improve      ║
  ║ Flutter tools over time.                                                   ║
  ║                                                                            ║
  ║ Flutter tool analytics are not sent on the very first run. To disable      ║
  ║ reporting, type 'flutter config --no-analytics'. To display the current    ║
  ║ setting, type 'flutter config'. If you opt out of analytics, an opt-out    ║
  ║ event will be sent, and then no further information will be sent by the    ║
  ║ Flutter tool.                                                              ║
  ║                                                                            ║
  ║ By downloading the Flutter SDK, you agree to the Google Terms of Service.  ║
  ║ Note: The Google Privacy Policy describes how data is handled in this      ║
  ║ service.                                                                   ║
  ║                                                                            ║
  ║ Moreover, Flutter includes the Dart SDK, which may send usage metrics and  ║
  ║ crash reports to Google.                                                   ║
  ║                                                                            ║
  ║ Read about data we send with crash reports:                                ║
  ║ https://flutter.dev/docs/reference/crash-reporting                         ║
  ║                                                                            ║
  ║ See Google's privacy policy:                                               ║
  ║ https://policies.google.com/privacy                                        ║
  ╚════════════════════════════════════════════════════════════════════════════╝

```

`$ Flutter` とだけ実行すると `Flutter` の使い方が出力されます。

```sh
$ flutter
Manage your Flutter app development.

Common commands:

  flutter create <output directory>
    Create a new Flutter project in the specified directory.

  flutter run [options]
    Run your Flutter application on an attached device or in an emulator.

Usage: flutter <command> [arguments]

Global options:
-h, --help                  Print this usage information.
-v, --verbose               Noisy logging, including all shell commands executed.
                            If used with "--help", shows hidden options. If used with "flutter doctor", shows additional diagnostic information. (Use "-vv" to force verbose logging in those
                            cases.)
-d, --device-id             Target device id or name (prefixes allowed).
    --version               Reports the version of this tool.
    --suppress-analytics    Suppress analytics reporting when this command runs.

Available commands:

Flutter SDK
  bash-completion   Output command line shell completion setup scripts.
  channel           List or switch Flutter channels.
  config            Configure Flutter settings.
  doctor            Show information about the installed tooling.
  downgrade         Downgrade Flutter to the last active version for the current channel.
  precache          Populate the Flutter tool's cache of binary artifacts.
  upgrade           Upgrade your copy of Flutter.

Project
  analyze           Analyze the project's Dart code.
  assemble          Assemble and build Flutter resources.
  build             Build an executable app or install bundle.
  clean             Delete the build/ and .dart_tool/ directories.
  create            Create a new Flutter project.
  drive             Run integration tests for the project on an attached device or emulator.
  format            Format one or more Dart files.
  gen-l10n          Generate localizations for the current project.
  pub               Commands for managing Flutter packages.
  run               Run your Flutter app on an attached device.
  test              Run Flutter unit tests for the current project.

Tools & Devices
  attach            Attach to a running app.
  custom-devices    List, reset, add and delete custom devices.
  devices           List all connected devices.
  emulators         List, launch and create emulators.
  install           Install a Flutter app on an attached device.
  logs              Show log output for running Flutter apps.
  screenshot        Take a screenshot from a connected device.
  symbolize         Symbolize a stack trace from an AOT-compiled Flutter app.

Run "flutter help <command>" for more information about a command.
Run "flutter help -v" for verbose help output, including less commonly used options.
```

# 参考

https://github.com/oae/asdf-flutter