Home/ Questions/Q 261729
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-11T22:27:23+00:00

Is there a way to check if some gem is currently installed, via the

  • 0

Is there a way to check if some gem is currently installed, via the Gem module? From ruby code, not by executing ‘gem list’…

To clarify – I don’t want to load the library. I just want to check if it’s available, so all the rescue LoadError solutions don’t help me. Also I don’t care if the gem itself will work or not, only whether it’s installed.

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    IMHO the best way is to try to load/require the GEM and rescue the Exception, as Ray has already shown. It’s safe to rescue the LoadError exception because it’s not raised by the GEM itself but it’s the standard behavior of the require command.

    You can also use the gem command instead.

    begin
  gem "somegem"
  # with requirements
  gem "somegem", ">=2.0"
rescue Gem::LoadError
  # not installed
end

    The gem command has the same behavior of the require command, with some slight differences. AFAIK, it still tries to autoload the main GEM file.

    Digging into the rubygems.rb file (line 310) I found the following execution

    matches = Gem.source_index.find_name(gem.name, gem.version_requirements)
report_activate_error(gem) if matches.empty?

    It can provide you some hints about how to make a dirty check without actually loading the library.

    • 0