How to format irb command prompt

Question

Previously I was using Ruby 1.8 and my irb command prompt used to look like this:

Air ~: irb
>> a = 1
=> 1
>> b = 2
=> 2
>&         


        

Answer 1

Whoever want to add a prompt timestamp, this isn't possible yet (check "special strings" section), so I implemented it in a monkey-patchy way:

module IrbTimePrompt
  def prompt(prompt, ltype, indent, line_no)
    # I used %T as time format, but you could use whatever you want to.
    # Check https://apidock.com/ruby/Time/strftime for more options
    p = prompt.dup.gsub(/%t/, Time.new.strftime('%T'))
    super(p, ltype, indent, line_no)
  end
end

module IRB
  class Irb
    prepend IrbTimePrompt
  end
end

Now, add this to your lib/ project folder (in case is a Rails project, ensure lib/ is part of config.autoload_paths in config/application.rb) or in a more aggresive way (not recommended), look for lib/irb.rb file in your local ruby instance and in def prompt method, add a new when condition to the method, like:

    when "t"
      Time.now.strftime('%-d-%-m %T%Z')

then in your .irbrc file (it could be located in your home folder or root project folder) you could modify your prompt. I'm adding my current prompt, but please adjust it to your needs:

def rails_prompt
  # This is my base prompt, displaying line number and time
  def_prompt = '[%01n][%t]'
  # Maybe you're only running as `irb` an not `rails console`, so check first
  # if rails is available
  if defined? Rails
    app_env = Rails.env[0...4]
    if Rails.env.production?
      puts "\n\e[1m\e[41mWARNING: YOU ARE USING RAILS CONSOLE IN PRODUCTION!\n" \
           "Changing data can cause serious data loss.\n" \
           "Make sure you know what you're doing.\e[0m\e[22m\n\n"
      app_env = "\e[31m#{app_env}\e[0m" # red
    else
      app_env = "\e[32m#{app_env}\e[0m" # green
    end
    def_prompt << "(\e[1m#{app_env}\e[22m)" # bold
  end

  IRB.conf[:PROMPT] ||= {}
  IRB.conf[:PROMPT][:WITH_TIME] = {
    PROMPT_I: "#{def_prompt}> ",
    PROMPT_N: "#{def_prompt}| ",
    PROMPT_C: "#{def_prompt}| ",
    PROMPT_S: "#{def_prompt}%l ",
    RETURN: "=> %s\n",
    AUTO_INDENT: true,
  }
  IRB.conf[:PROMPT_MODE] = :WITH_TIME
end

rails_prompt

Then start irb or rails console and check the awesomeness:

[1][13:01:15](deve)> 'say hello to your new prompt'
=> "say hello to your new prompt"
[2][13:01:23](deve)>