How can I write a hook that gets called when a RubyGem is installed?

问题

I'd like to write a Ruby snippet that gets run when my Gem is first installed via [sudo ]gem install mygem. Can it be done?

回答1:

It doesn't look like it's really supported. I found a "post_install_message" attribute that you should be able to set in the gem spec, but that won't execute code.

You may be able to do it by packaging your on-install code as an extension in your gem (as if it were a native extension), and providing a Rakefile to "build" the extension (i.e. call your code).

回答2:

I had the same problem. The best solution that I found is as follows:

# your_gem.gemspec
Gem::Specification.new do |spec|
  # ...
  spec.extensions = ['Rakefile']
end

-

# Rakefile
task :prepare do
  # Execute your post-installation code here
end

task default: :prepare

回答3:

You can try to do this using call of OS commands. I'll quote eample from irb but you can do same in your scripts too.

irb(main):001:0> system 'gem list | grep rails'
rails (2.1.1, 2.1.0)
=> true
irb(main):002:0> system 'gem list | grep railssssss'
=> false

You can use result of this command as the condition of your snippet execution.

来源：https://stackoverflow.com/questions/223151/how-can-i-write-a-hook-that-gets-called-when-a-rubygem-is-installed