Set git hook that runs ctags automatically after each pool, commit and checkout. Got from https://gist.github.com/tobias/42308/raw/2e7b7072278a2ba65e9d95597e148498d9ba7654/run_tags.rb and refactore. Need to set it more flexible.

run_tags.rb

#!/usr/bin/env ruby
# A script to run ctags on all .rb files in a project. Can be run on
# the current dir, called from a git callback, or install itself as a
# git post-merge and post-commit callback.

CTAGS = '/usr/bin/env ctags'
HOOKS = %w{ post-merge post-commit post-checkout }
HOOKS_DIR = '.git/hooks'

def install
  unless File.writable?(HOOKS_DIR)
    $stderr.print "The install option [-i] can only be used within a git repo; exiting.\n"
    exit 1
  end

  HOOKS.each { |hook| install_hook("#{HOOKS_DIR}/#{hook}") }
end

def run_tags(dir, run_in_background = false)
  return unless all_good?(dir)
  find_files = "find #{dir} -name \\\*.rb"
  generate_tags = "#{CTAGS} -f #{dir}/tags -L - 2>>/dev/null"
  cmd = "#{find_files} | #{generate_tags}"
  cmd << ' &' if run_in_background
  $stderr.print "calling #{cmd}\n"
  system cmd
end

def all_good?(dir)
  unless File.writable?(dir)
    $stderr.print "#{dir} file is not writable"
    return false
  end
  return true
end


def install_hook(hook)
  if File.exists?(hook)
    $stderr.print "A file already exists at #{hook}, and will NOT be replaced.\n"
    return
  end

  print "Linking #{__FILE__} to #{hook}\n"
  %x{ln -s #{__FILE__}  #{hook}}
end

if ARGV.first == '-i'
  install
else
  run_tags Dir.pwd, HOOKS.include?(File.basename(__FILE__))
end