io 0.3.4

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Contains utilities for the Dart VM's dart:io.

pub package Build Status

Usage - io.dart #

Files #


Returns whether a provided file path is considered executable on the host operating system.

Processes #


An enum-like class that contains known exit codes.


A higher-level service for spawning and communicating with processes.

Use spawn to create a process with std[in|out|err] forwarded by default
/// Runs `dartfmt` commands and `pub publish`.
Future<Null> main() async {
  final manager = new ProcessManager();
  // Runs dartfmt --version and outputs the result via stdout.
  print('Running dartfmt --version');
  var spawn = await manager.spawn('dartfmt', ['--version']);
  await spawn.exitCode;
  // Runs dartfmt -n . and outputs the result via stdout.
  print('Running dartfmt -n .');
  spawn = await manager.spawn('dartfmt', ['-n', '.']);
  await spawn.exitCode;
  // Runs pub publish. Upon hitting a blocking stdin state, you may directly
  // output to the processes's stdin via your own, similar to how a bash or
  // shell script would spawn a process.
  print('Running pub publish');
  spawn = await manager.spawn('pub', ['publish']);
  await spawn.exitCode;
  // Closes stdin for the entire program.
  await sharedStdIn.terminate();


A safer version of the default stdin stream from dart:io that allows a subscriber to cancel their subscription, and then allows a new subscriber to start listening. This differs from the default behavior where only a single listener is ever allowed in the application lifecycle:

test('should allow multiple subscribers', () async {
  final logs = <String>[];
  final asUtf8 = sharedStdIn.transform(UTF8.decoder);
  // Wait for input for the user.
  logs.add(await asUtf8.first);
  // Wait for more input for the user.
  logs.add(await asUtf8.first);
  expect(logs, ['Hello World', 'Goodbye World']);

For testing, an instance of SharedStdIn may be created directly.

Usage - ansi.dart #

import 'dart:io' as io;
import 'package:io/ansi.dart';

void main() {
  // To use one style, call the `wrap` method on one of the provided top-level
  // values.
  io.stderr.writeln(red.wrap("Bad error!"));

  // To use multiple styles, call `wrapWith`.
  print(wrapWith('** Important **', [red, styleBold, styleUnderlined]));

  // The wrap functions will simply return the provided value unchanged if
  // `ansiOutputEnabled` is false.
  // You can override the value `ansiOutputEnabled` by wrapping code in
  // `overrideAnsiOutput`.
  overrideAnsiOutput(false, () {
    assert('Normal text' == green.wrap('Normal text'));

0.3.4 #

  • Fix a number of issues affecting the package score on

0.3.3 #

  • Updates for Dart 2 constants. Require at least Dart 2.0.0-dev.54.

  • Fix the type of StartProcess typedef to match Process.start from dart:io.

0.3.2+1 #

  • ansi.dart

    • The "forScript" code paths now ignore the ansiOutputEnabled value. Affects the escapeForScript property on AnsiCode and the wrap and wrapWith functions when forScript is true.

0.3.2 #

  • ansi.dart

    • Added forScript named argument to top-level wrapWith function.

    • AnsiCode

      • Added String get escapeForScript property.

      • Added forScript named argument to wrap function.

0.3.1 #

  • Added SharedStdIn.nextLine (similar to readLineSync) and lines:
main() async {
  // Prints the first line entered on stdin.
  print(await sharedStdIn.nextLine());
  // Prints all remaining lines.
  await for (final line in sharedStdIn.lines) {
  • Added a copyPath and copyPathSync function, similar to cp -R.

  • Added a dependency on package:path.

  • Added the remaining missing arguments to ProcessManager.spawnX which forward to Process.start. It is now an interchangeable function for running a process.

0.3.0 #

  • BREAKING CHANGE: The arguments argument to ProcessManager.spawn is now positional (not named) and required. This makes it more similar to the built-in Process.start, and easier to use as a drop in replacement:
main() {
  processManager.spawn('dart', ['--version']);
  • Fixed a bug where processes created from ProcessManager.spawn could not have their stdout/stderr read through their respective getters (a runtime error was always thrown).

  • Added ProcessMangaer#spawnBackground, which does not forward stdin.

  • Added ProcessManager#spawnDetached, which does not forward any I/O.

  • Added the shellSplit() function, which parses a list of arguments in the same manner as the POSIX shell.

0.2.0 #

  • Initial commit of...
    • FutureOr<bool> String isExecutable(path).
    • ExitCode
    • ProcessManager and Spawn
    • sharedStdIn and SharedStdIn
    • ansi.dart library with support for formatting terminal output


// Copyright 2017, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import 'dart:math';

import 'package:io/ansi.dart';

/// Prints a sample of all of the `AnsiCode` values.
void main(List<String> args) {
  final forScript = args.contains('--for-script');

  if (!ansiOutputEnabled) {
    print('`ansiOutputEnabled` is `false`.');
    print("Don't expect pretty output.");
  _preview('Foreground', foregroundColors, forScript);
  _preview('Background', backgroundColors, forScript);
  _preview('Styles', styles, forScript);

void _preview(String name, List<AnsiCode> values, bool forScript) {
  final longest = =>;

  print(wrapWith('** $name **', [styleBold, styleUnderlined]));
  for (var code in values) {
    final header =
        '${} ${code.code.toString().padLeft(3)}';

    print("$header: ${code.wrap('Sample', forScript: forScript)}");

Use this package as a library

1. Depend on it

Add this to your package's pubspec.yaml file:

  io: ^0.3.4

2. Install it

You can install packages from the command line:

with pub:

$ pub get

with Flutter:

$ flutter pub get

Alternatively, your editor might support pub get or flutter pub get. Check the docs for your editor to learn more.

3. Import it

Now in your Dart code, you can use:

import 'package:io/io.dart';
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Learn more about scoring.

We analyzed this package on Jun 5, 2020, and provided a score, details, and suggestions below. Analysis was completed with status completed using:

  • Dart: 2.8.2
  • pana: 0.13.8-dev

Health suggestions

Fix lib/src/permissions.dart. (-1.99 points)

Analysis of lib/src/permissions.dart reported 4 hints:

line 11 col 3: The value of the field 'write' isn't used.

line 12 col 3: The value of the field 'read' isn't used.

line 21 col 3: The value of the field 'group' isn't used.

line 22 col 3: The value of the field 'user' isn't used.


Package Constraint Resolved Available
Direct dependencies
Dart SDK >=2.0.0 <3.0.0
charcode ^1.0.0 1.1.3
meta ^1.0.2 1.1.8
path ^1.5.1 1.7.0
string_scanner >=0.1.5 <2.0.0 1.0.5
Transitive dependencies
collection 1.14.12
source_span 1.7.0
term_glyph 1.1.0
Dev dependencies
dart_style ^1.0.7
pedantic ^1.2.0
test ^1.0.0
test_descriptor ^1.0.0