Termline provides human-friendly terminal output for applications and development tools built with the Lesli Framework.

It exposes a small Ruby API for semantic messages, colors, icons, structured metadata, lists, tables, and separators. Termline has no application-framework dependency, so it can also be used by standalone Ruby applications, scripts, Rake tasks, and command-line tools.

Termline provides:

• Consistent terminal output across the Lesli ecosystem
• Semantic info, success, warning, and danger messages
• Colored icons, labels, and timestamps
• Structured key-value metadata
• Ordered and unordered lists
• Terminal-aware tables with alignment and truncation
• Reusable titles, detail blocks, spacing, and adaptive separators
• A lightweight implementation with no runtime dependencies

• Ruby 2.7.2 or newer

Termline is framework-independent and does not require Rails.

Add Termline to the application:

bundle add termline

Require the gem when Bundler does not load it automatically:

require "termline"

require "termline"

Termline.msg "Hello world"
Termline.info "Server started"
Termline.success "All tests passed"
Termline.warning "Low disk space"
Termline.danger "Something failed"

Every semantic helper accepts multiple messages and prints each one on its own line:

Termline.info "Loading configuration", "Connecting to database"

Attach structured metadata with keyword arguments:

Termline.success "Compiled application.tailwind.css", size: "1.4 KB"
Termline.info "Connected", adapter: "postgres", duration: "12ms"

Metadata is rendered in a compact, readable form such as adapter=postgres duration=12ms.

Override the default tag, icon, or timestamp when the output needs a different presentation:

Termline.info "User authenticated", tag: "AUTH:", icon: :star
Termline.success "Cache warmed", time: false

Timestamp defaults can also be configured once for the application:

Termline.configure do |config|
  config.timestamps = false
  config.timestamp_format = "%H:%M:%S"
end

Termline.list("Rails", "Lesli", "Tailwind")
Termline.list("Database", "Cache", icon: :success, color: :green)
Termline.ordered_list("Install", "Configure", "Run", start: 1)

Termline.table([
  { name: "Luis", role: "Admin", status: "Active" },
  { name: "Ana", role: "Developer", status: "Pending" }
], align: { name: :left, status: :center })

Tables fit the available terminal width, truncate long values with …, and right-align numeric columns automatically.

Termline.title "Deployment"
Termline.details environment: "production", version: "1.4.0"
Termline.details({ status: "ready", workers: 4 }, icons: { status: :success, workers: :info })

Termline.br
Termline.br(2)
Termline.line
Termline.line(character: "=")

Without arguments, line adapts to the current terminal width.

Message, list, table, and spacing helpers write to the configured output, which defaults to $stdout. See the focused guides for all supported options and lower-level builders:

• Installation
• Messages
• Lists
• Tables
• Details
• Titles
• Separators and spacing

Termline writes to $stdout and enables ANSI styles automatically for interactive terminals. Redirect the output or override ANSI rendering when needed:

require "stringio"

buffer = StringIO.new
Termline.output = buffer
Termline.ansi = false

Termline.success "Saved", time: false
buffer.string # => "✔ SUCCESS: Saved\n"

The supported ANSI modes are :auto, true, and false. Automatic mode disables escape sequences when the output is not a TTY, when TERM=dumb, or when the NO_COLOR environment variable is present.

The terminal width is detected when content is rendered and falls back to 80 columns. It can be overridden explicitly:

Termline.width = 100

Message timestamps are enabled by default. Use Termline.timestamps = false to disable them globally, and time: true or time: false to override the setting for one message.

Clone the repository and install its dependencies:

git clone https://github.com/LesliTech/Termline.git
cd Termline
bundle install

To use local source from a Lesli development workspace, reference it from the host application's Gemfile:

gem "termline", path: "gems/Termline"

Run the default test task from the Termline directory:

bundle exec rake

The suite uses LesliTesting for the shared Lesli reporter and coverage configuration. Coverage is opt-in:

COVERAGE=true bundle exec rake

Use QUIET=true to suppress the line printed for every individual test:

QUIET=true COVERAGE=true bundle exec rake

Run the executable examples to preview the available output styles:

bundle exec ruby test/demo_termline.rb

• Lesli website
• Termline documentation
• Testing guide
• Roadmap and P3 ToDo
• Releases and changelog
• Issue tracker
• Source code

• X: @LesliTech
• hello@lesli.tech
• https://www.lesli.tech

Copyright (c) 2026, Lesli Technologies, S. A.

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see https://www.gnu.org/licenses/.

The complete license text is available in the license file.

The Open-Source SaaS Development Framework for Ruby on Rails.