Simple Command Line Parser

Easy library to validate and parse command line parameters.

This gem has been designed as a part of the BlackStack framework.

I ran tests on:

• Ubuntu 18.04,
• Ubuntu 20.04, and
• Windows 7 only.

Email to me if you want to collaborate.

Outline

1. Installation
2. Getting Started
3. Missing Parameters
4. Optional Parameters
5. Type Mismatching

1. Installation

gem install simple_command_line_parser

2. Getting Started

The command line parser & validation will be done in the same moment when you create the parser object.

As an example, create the a new file,

touch ~/example.rb

And write this script there:

require 'simple_command_line_parser'

parser = nil

print "Parse command line... "
begin
  parser = BlackStack::SimpleCommandLineParser.new(
    :description => 'This example command would downolad and install a software.', 
    :configuration => [{
        :name=>'url', 
        :mandatory=>true, 
        :description=>'URL from where download the installer.', 
        :type=>BlackStack::SimpleCommandLineParser::STRING,
      },
      {
        :name=>'max_retries', 
        :mandatory=>true, 
        :description=>'Max number of download retries if the download keep failing.', 
        :type=>BlackStack::SimpleCommandLineParser::INT,
      },
      {
        :name=>'check_for_virus', 
        :mandatory=>true, 
        :description=>'Run verifications when login.', 
        :type=>BlackStack::SimpleCommandLineParser::BOOL,
      },
    ]
  )
  puts "done"
  puts ""
  puts "Param url == #{parser.value('url').to_s}"
  puts "Param max_retries == #{parser.value('max_retries').to_s}"
  puts "Param check_for_virus == #{parser.value('check_for_virus').to_s}"
  puts ""

  # TODO: Code your process here.

  puts "Bye!"
rescue => e
  puts "error"
  puts e.to_s
end

Try running the script:

ruby ~/example.rb url=foo.com max_retries=2 check_for_virus=yes

Parse command line... done

Param url == foo.com
Param max_retries == 2
Param check_for_virus == true

Bye!

3. Missing Parameters

Using the same code than the previous sections, will raise an exception if one of the parameters is missed in the command line.

ruby ~/example.rb url=foo.com max_retries=2

Parse command line... error
Command line parameter check_for_virus expected.

4. Optional Parameters

You can make some parameters not mandatory (optional), but you have to setup a default value for them.

require 'simple_command_line_parser'

parser = nil

print "Parse command line... "
begin
  parser = BlackStack::SimpleCommandLineParser.new(
    :description => 'This example command would downolad and install a software.', 
    :configuration => [{
        :name=>'url', 
        :mandatory=>true, 
        :description=>'URL from where download the installer.', 
        :type=>BlackStack::SimpleCommandLineParser::STRING,
      },
      {
        :name=>'max_retries', 
        :mandatory=>true, 
        :description=>'Max number of download retries if the download keep failing.', 
        :type=>BlackStack::SimpleCommandLineParser::INT,
      },
      {
        :name=>'check_for_virus', 
        :mandatory=>false, # <==== OPTIONAL PARAMETER
        :description=>'Run verifications when login.', 
        :type=>BlackStack::SimpleCommandLineParser::BOOL,
        :default=>false
      },
    ]
  )
  puts "done"
  puts ""
  puts "Param url == #{parser.value('url').to_s}"
  puts "Param max_retries == #{parser.value('max_retries').to_s}"
  puts "Param check_for_virus == #{parser.value('check_for_virus').to_s}"
  puts ""
  puts "Bye!"
rescue => e
  puts "error"
  puts e.to_s
end 

ruby ~/example.rb url=foo.com max_retries=2

Parse command line... done

Param url == foo.com
Param max_retries == 2
Param check_for_virus == false

Bye!

5. Type Mismatching

If you declare a parameters as an integer, you can't send other value than an integer in the command line.

ruby ~/example.rb url=foo.com max_retries=not-an-integer

Parse command line... error
Type mismatch for the command line parameter max_retries.

If you declare a parameter as a boolean, you can'tsend other value than 'yes' or 'no' in the command line

ruby ~/example.rb url=foo.com max_retries=2 check_for_virus=maybe

Parse command line... error
Type mismatch for the command line parameter check_for_virus.

Versioning

We use SemVer for versioning. For the versions available, see the last ruby gem.

Authors

• Leandro Daniel Sardi - Initial work - LeandroSardi

License

This project is licensed under the MIT License - see the LICENSE.md file for details