What does DCli do?

DCli has a singular focus:

make it easy to build command line apps using the Dart programming language.

DCli has the following aims:

• make building CLI apps as easy as walking.

• fully utilise the expressiveness of Dart.

• works seamlessly with the core Dart libraries.

• provide a cross platform API for Windows, OSx and Linux.

• call any CLI app.

• make debugging CLI apps easy.

• generate error messages that make it easy to resolve problems.

• provide quality documentation and examples.

DCli's API covers a number of areas:

User input

Asking the user to input data into a CLI application should be simple. DCli provides a number of functions to facilitate user input.

• ask

• confirm

• menu

import 'package:dcli/dcli.dart';
void main(){
   var username = ask('Username:', validator: Ask.required);
   if (confirm('Are you over 18')) {
       print(orange('Welcome to the club'));
   }
   
   var selected = menu('Select your poison', options: ['beer', 'wine', 'spirits']
      defaultOption: 'beer');
   print(green('You choice was: $selected'));
}

DCli provides an extensive API designed specifically for building command-line apps.

Displaying information

Out-of-the-box Dart provides the basic 'print' statement which DCli extends to provide common features.

• print

• printerr - prints to stderr.

• colour coding

• cursor management

• clear screen/clear line

print(orange("I'm an important message"));
printerr(red('Oops, something went wrong here'));

Manage files and directories

A fundamental task of most CLI applications is the management of files and directories. DCli provides a large set of tools for file management such as:

• find

• which

• copy

• copyTree

• move

• moveTree

• delete

• deleteDir

• touch

• exists

• isWritable/isReadable/isExecutable

• isFile

• isLink

• isDirectory

• lastModified

Dart has a large ecosystem of packages that you can use to extend the DCli such as the excellent paths package that lets you easily manipulate file paths.

import 'package:dcli/dcli.dart';
void main() {
    if (!exists('/keep')) {
        createDir('/keep');
    }
    
    var images = find('*.png', root: '/images');
    for (var image in images) {
        if (image.startsWith('nsfw')) {
            copy(image, '/keep');
        }
    }
}

Read/Write files

You are often going to need to read/write and modify text and binary files.

• read

• write

• truncate

• append

• replace

• tail

• cat

You still have full access to the full set of Dart APIs

//  write lines to myfile.ini
var settings = 'myfile.ini';
settings.write('[section1]');
settings.append('color=red');
settings.append('color=blue');

// fix the spelling in myfile.ini
replace(settings, 'color', 'colour');

Call command line apps

A core feature of DCli is the ability to call other CLI apps and process their output.

• run

• start

• toList

• forEach

• firstLine

• lastLine

• | (pipe)

• stream

Run mysql with all output being displayed to the console.

var user = ask('username');
var password = ask('password', hidden:true);
'mysql -u $user --password=$password customerdb -e "select 1"'.run;

Run a mysql command and store the results in a list (users).

var users = 'mysql customerdb -e "select fname, sname from user"'
    .toList(skipLines: 1);
/// now parse each user and print their name
for (var user in users) {
    var parts = user.split(',');
    print('Firstname: ${parts[0]} Surname: ${parts[1]});
}
/// Run grep and print each line that it finds
'grep error /var/lib/syslog'.forEach((line) => print(line));

Explore you environment

DCli makes it easy to explore your environment with direct manipulation of environment variables.

var user = env['USER'];
env['JAVA_HOME'] = '/usr/lib/java';

PATH management tools:

Env().appendToPath('/home/me/bin');
Env().addToPATHIfAbsent('/home/me/bin');
Env().removeFromPATH('/home/me/bin');

And the ability to explore the Dart environment.

/// Get details of the current dart script that is running.
DartScript.current;
DartSdk().pathToDartExe;
PubCache().pathTo

You can explore the complete API here.