Colorized Ruby output to the terminal [closed]

Answer 1

While the other answers will do the job fine for most people, the "correct" Unix way of doing this should be mentioned. Since all types of text terminals do not support these sequences, you can query the terminfo database, an abstraction over the capabilites of various text terminals. This might seem mostly of historical interest – software terminals in use today generally support the ANSI sequences – but it does have (at least) one practical effect: it is sometimes useful to be able to set the environment variable TERM to dumb to avoid all such styling, for example when saving the output to a text file. Also, it feels good to do things right. :-)

You can use the ruby-terminfo gem. It needs some C compiling to install; I was able to install it under my Ubuntu 14.10 system with:

$ sudo apt-get install libncurses5-dev
$ gem install ruby-terminfo --user-install

Then you can query the database like this (see the terminfo man page for a list of what codes are available):

require 'terminfo' 
TermInfo.control("bold")
puts "Bold text"
TermInfo.control("sgr0")
puts "Back to normal."
puts "And now some " + TermInfo.control_string("setaf", 1) + 
     "red" + TermInfo.control_string("sgr0") + " text."

Here's a little wrapper class I put together to make things a little more simple to use.

require 'terminfo'

class Style
  def self.style() 
    @@singleton ||= Style.new
  end

  colors = %w{black red green yellow blue magenta cyan white}
  colors.each_with_index do |color, index|
    define_method(color) { get("setaf", index) }
    define_method("bg_" + color) { get("setab", index) }
  end

  def bold()  get("bold")  end
  def under() get("smul")  end
  def dim()   get("dim")   end
  def clear() get("sgr0")  end

  def get(*args)
    begin
      TermInfo.control_string(*args)
    rescue TermInfo::TermInfoError
      ""
    end
  end
end

Usage:

c = Style.style
C = c.clear
puts "#{c.red}Warning:#{C} this is #{c.bold}way#{C} #{c.bg_red}too much #{c.cyan + c.under}styling#{C}!"
puts "#{c.dim}(Don't you think?)#{C}"

(edit) Finally, if you'd rather not require a gem, you can rely on the tput program, as described here – Ruby example:

puts "Hi! " + `tput setaf 1` + "This is red!" + `tput sgr0`