This is my current irbrc file which contains lots of helpful things.

.irbrc

# ActiveRecord::Base.logger.level = 1
# IRB.conf[:ECHO] = false

# Overriding Object class
class Object
  # Easily print methods local to an object's class
  def lm
    (methods - Object.instance_methods).sort
  end

  # look up source location of a method
  def sl(method_name)
    self.method(method_name).source_location rescue "#{method_name} not found"
  end

  # open particular method in vs code
  def ocode(method_name)
    file, line = self.sl(method_name)
    if file && line
      `code -g '#{file}:#{line}'`
    else
      "'#{method_name}' not found :(Try #{self.name}.lm to see available methods"
    end
  end

  # display method source in rails console
  def sd(method_name)
    self.method(method_name).source.display
  end
end

# Print History
def phist
  puts Readline::HISTORY.to_a
end

# copy a string to the clipboard
def cp(string)
  `echo "#{string}" | pbcopy`
  puts "copied in clipboard"
end

# Get current logged-in user for selldo
def getcu
  begin
    last_lines = `tail -n 500 'log/development.log'`;nil
    User.find(last_lines[(last_lines.rindex("logged_in_user:") + 15), 24])
  rescue Exception => e
    puts "Error in getting user - #{e.message}"
  end
end

# Get client for currently loggedin user
def getc
  begin
    getcu.client
  rescue Exception => e
    puts "Error in getting user - #{e.message}"
  end
end

# reloads the irb console can be useful for debugging .irbrc
def reload_irb
  load File.expand_path("~/.irbrc")
  # will reload rails env if you are running ./script/console
  reload! if @script_console_running
  puts "Console Reloaded!"
end

# opens irbrc in vscode
def edit_irb
  `code ~/.irbrc` if system("code")
end

# exit using `q`
alias q exit