CLI UI is a small framework for generating nice command-line user interfaces


“sh gem install cli-ui

or add the following to your Gemfile:

“by gem ‘cli-ui’

In your code, simply add a require 'cli/ui'. Most options assume CLI::UI::StdoutRouter.enable has been called.


This may not be an exhaustive list. Please check our documentation for more information.

Nested framing

To handle content flow (see example below)

“by CLI::UI::StdoutRouter.enable‘Frame 1’) do‘Frame 2’) { puts “inside frame 2” } puts “inside frame 1” end

Nested Framing

Interactive Prompts

Prompt user with options and ask them to choose. Can answer using arrow keys, vim bindings (j/k), or numbers (or y/n for yes/no questions).

For large numbers of options, using e, :, or G will toggle “line select” mode which allows numbers greater than 9 to be typed and f or / will allow the user to filter options using a free-form text input.

“by CLI::UI.ask(‘What language/framework do you use?’, options: %w(rails go ruby python))

Can also assign callbacks to each option

“by CLI::UI::Prompt.ask(‘What language/framework do you use?’) do |handler| handler.option(‘rails’) { |selection| selection } handler.option(‘go’) { |selection| selection } handler.option(‘ruby’) { |selection| selection } handler.option(‘python’) { |selection| selection } end

  • Note that the two examples provided above are identical in functionality

Interactive Prompt

Free form text prompts

“by CLI::UI.ask(‘Is CLI UI Awesome?’, default: ‘It is great!’)

Free form text prompt

Spinner groups

Handle many multi-threaded processes while suppressing output unless there is an issue. Can update title to show state.

“by do |spin_group| spin_group.add(‘Title’) { |spinner| sleep 3.0 } spin_group.add(‘Title 2’) { |spinner| sleep 3.0; spinner.update_title(‘New Title’); sleep 3.0 } end

Spinner Group

Text Color formatting

e.g. {{red:Red}} {{green:Green}}

“by puts CLI::UI.fmt “{red:Red} {green:Green}”

Text Format

Symbol/Glyph Formatting

e.g. {{*}} => a yellow ⭑

“by puts CLI::UI.fmt “{<em>} {v} {?} {x}“

Symbol Formatting

Status Widget

“by CLI::UI::Spinner.spin(“building packages: {@widget/status:1:2:3:4}”) do |spinner| # spinner.update_title(…) sleep(3) end

Status Widget

Progress Bar

Show progress of a process or operation.

“by CLI::UI::Progress.progress do |bar| 100.times do bar.tick end end

Progress Bar

Frame Styles

Modify the appearance of CLI::UI both globally and on an individual frame level.

To set the default style:

“by CLI::UI.frame_style = :box

To style an individual frame:

“by CLI::UI.frame(‘New Style!’, frame_style: :bracket) { puts ‘It’s pretty cool!’ }

The default style - :box - is what has been used up until now. The other style - :bracket - looks like this:

“by CLI::UI.frame_style = :bracket CLI::UI::StdoutRouter.enable‘Frame 1’) do‘Frame 2’) { puts “inside frame 2” } puts “inside frame 1” end

Frame Style

Example Usage

The following code makes use of nested-framing, multi-threaded spinners, formatted text, and more.

“by require ‘cli/ui’

CLI::UI::StdoutRouter.enable‘{<em>} {bold:a}‘, color: :green) do’{i} b’, color: :magenta) do‘{?} c’, color: :cyan) do do |sg| sg.add(‘wow’) do |spinner| sleep(2.5) spinner.update_title(‘second round!’) sleep (1.0) end sg.add(‘such spin’) { sleep(1.6) } sg.add(‘many glyph’) { sleep(2.0) } end end end CLI::UI::Frame.divider(‘{v} lol’) puts CLI::UI.fmt ‘{info:words} no!} {green:success!}’ do |sg| sg.add(‘more spins’) { sleep(0.5) ; raise ‘oh no’ } end end


Example Output


  • Run tests using bundle exec rake test. All code should be tested.
  • No code, outside of development and tests needs, should use dependencies. This is a self contained library


Bug reports and pull requests are welcome on GitHub at


The code is available as open source under the terms of the MIT License.