detect tty width & height

tty_info.rb

# Determines if a shell command exists by searching for it in ENV['PATH'].
def command_exists?(command)
  ENV['PATH'].split(File::PATH_SEPARATOR).any? {
    |d| File.exists? File.join(d, command)
  } 
end 
  
# Returns [width, height] of terminal when detected, nil if not detected.
def detect_terminal_size
  @log.debug_var binding, "ENV['COLUMNS']", "ENV['LINES']"
  if (ENV['COLUMNS'] =~ /^\d+$/) && (ENV['LINES'] =~ /^\d+$/)
    [ENV['COLUMNS'].to_i, ENV['LINES'].to_i]
  elsif (RUBY_PLATFORM =~ /java/ || (!STDIN.tty? && ENV['TERM'])) && command_exists?('tput')
    [`tput cols`.to_i, `tput lines`.to_i]
  elsif STDIN.tty? && command_exists?('stty')
    `stty size`.scan(/\d+/).map { |s| s.to_i }.reverse
  else
    [0, 0]
  end 
rescue
  [0, 0]
end

unix - How to get the width of terminal window in Ruby - Stack Overflow