A snippet of code from HIRB to detect the terminal width.

terminal-width.rb

def detect_terminal_size
  if (ENV['COLUMNS'] =~ /^\d+$/) && (ENV['LINES'] =~ /^\d+$/)
    [ENV['COLUMNS'].to_i, ENV['LINES'].to_i]
  elsif (RUBY_PLATFORM =~ /java/ || !STDIN.tty?) && command_exists?('tput')
    [`tput cols`.to_i, `tput lines`.to_i]
  else
    command_exists?('stty') ? `stty size`.scan(/\d+/).map { |s| s.to_i }.reverse : nil
  end
rescue
  nil
end