How to Reference a Local Gem from a Ruby Script

How to reference a local gem from a ruby script?

Make sure that your gem name as same as in Gemfile (e.g. custom_gem)

# Gemfile

source "https://rubygems.org"

gem "custom_gem", path: "/home/username/path/to/custom_gem"

Don't forget to actually install this gem using bundler

bundle install

After that, the script should be ready to use by bundle exec ruby script.rb

# script.rb

require 'custom_gem'
CustomGem::Do.something

How can I specify a local gem in my Gemfile?

I believe you can do this:

gem "foo", path: "/path/to/foo"

Require local gem ruby

require checks for files in $LOAD_PATH. You can put your gem in one of those directories in order to require it directly. If you don't like your load path, you can add a new directory to it in your script, or set the RUBYLIB environment variable which is added to the load path.

How do I specify local .gem files in my Gemfile?

This isn't strictly an answer to your question about installing .gem packages, but you can specify all kinds of locations on a gem-by-gem basis by editing your Gemfile.

Specifying a :path attribute will install the gem from that path on your local machine.

gem "foreman", path: "/Users/pje/my_foreman_fork"

Alternately, specifying a :git attribute will install the gem from a remote git repository.

gem "foreman", git: "git://github.com/pje/foreman.git"

# ...or at a specific SHA-1 ref
gem "foreman", git: "git://github.com/pje/foreman.git", ref: "bf648a070c"

# ...or branch
gem "foreman", git: "git://github.com/pje/foreman.git", branch: "jruby"

# ...or tag
gem "foreman", git: "git://github.com/pje/foreman.git", tag: "v0.45.0"

(As @JHurrah mentioned in his comment.)

How to tell the Gem File to use a specific local copy of a gem

Try, in your Gemfile:

gem "mygem", :path => "/MyPath/MyGem.gem"

Note that it's probably best to use a relative link in there, like:

gem "mygem", :path => "vendor/MyPath/MyGem.gem"

Run gem from local source code

From the root directory of your gem, try this to execute lib/MyGem.rb:

ruby -Ilib lib/MyGem.rb

or test your gem interactive:

irb -Ilib
> require 'mygem'
true

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