Module 0x1 | Basic Ruby Kung Fu

Ruby has awesome abilities and tricks for dealing with all strings and arrays scenarios. In this chapter we'll present most known tricks we may need in our hacking life.

Terminal

Terminal size

Here are many ways to get terminal size from ruby

• By IO/console standard library

require 'io/console'
rows, columns = $stdin.winsize
# Try this now
print "-" * (columns/2) + "\n" + ("|" + " " * (columns/2 -2) + "|\n")* (rows / 2) + "-" * (columns/2) + "\n"

• By readline standard library

require 'readline'
Readline.get_screen_size

• Get terminal size in Environment like IRB or Pry

[ENV['LINES'].to_i, ENV['COLUMNS'].to_i]

• By tput command line

[`tput cols`.to_i , `tput lines`.to_i]

Console with tab completion

we can't stopping being jealous of Metasploit console(msfconsole) where we take a rest from command line switches. Fortunately, here is the main idea of tab completion console in ruby

• Readline

The Readline module provides interface for GNU Readline. This module defines a number of methods to facilitate completion and accesses input history from the Ruby interpreter.

console-basic1.rb

#!/usr/bin/env ruby
# KING SABRI | @KINGSABRI
# 
require 'readline'

# Prevent Ctrl+C for exiting
trap('INT', 'SIG_IGN')

# List of commands
CMDS = [ 'help', 'rubyfu', 'ls', 'pwd', 'exit' ].sort


completion = proc { |line| CMDS.grep( /^#{Regexp.escape( line )}/ ) }

# Console Settings
Readline.completion_proc = completion        # Set completion process
Readline.completion_append_character = ' '   # Make sure to add a space after completion

while line = Readline.readline('-> ', true)
  puts line unless line.nil? or line.squeeze.empty?
  break if line =~ /^quit.*/i or line =~ /^exit.*/i
end

Now run it and try the tab completion!

Well, The man idea in known the tab completion is make to do things easier not just pressing tab. Here a simple thought

console-basic2.rb

require 'readline'

# Prevent Ctrl+C for exiting
trap('INT', 'SIG_IGN')

# List of commands
CMDS = [ 'help', 'rubyfu', 'ls', 'exit' ].sort


completion = 
    proc do |str|
      case 
      when Readline.line_buffer =~ /help.*/i
    puts "Available commands:\n" + "#{CMDS.join("\t")}"
      when Readline.line_buffer =~ /rubyfu.*/i
    puts "Rubyfu, where Ruby goes evil!"
      when Readline.line_buffer =~ /ls.*/i
    puts `ls`
      when Readline.line_buffer =~ /exit.*/i
    puts 'Exiting..'
    exit 0
      else
    CMDS.grep( /^#{Regexp.escape(str)}/i ) unless str.nil?
      end
    end


Readline.completion_proc = completion        # Set completion process
Readline.completion_append_character = ' '   # Make sure to add a space after completion

while line = Readline.readline('-> ', true)  # Start console with character -> and make add_hist = true
  puts completion.call
  break if line =~ /^quit.*/i or line =~ /^exit.*/i
end

Things can go much father, msfconsole!

• Ruby Readline Documentation and Tutorial