How to Download a Ruby Gem Without Installing It Automatically

Is it possible to download a Ruby gem without installing it automatically?

gem fetch

So, something like $ gem fetch gosu ... this will leave gosu-0.7.14.gem in the current directory.

This will work even if you have already installed it.

Is it possible to download a platfrom specific Ruby gem without installing it?

$ gem fetch --help
Usage: gem fetch GEMNAME [GEMNAME ...] [options]

  Options:
    -v, --version VERSION            Specify version of gem to fetch
        --platform PLATFORM          Specify the platform of gem to fetch

  Local/Remote Options:
    -B, --bulk-threshold COUNT       Threshold for switching to bulk
                                     synchronization (default 1000)
    -p, --[no-]http-proxy [URL]      Use HTTP proxy for remote operations
        --source URL                 Use URL as the remote source for gems

  Common Options:
    -h, --help                       Get help on this command
    -V, --[no-]verbose               Set the verbose level of output
    -q, --quiet                      Silence commands
        --config-file FILE           Use this config file instead of default
        --backtrace                  Show stack backtrace on errors
        --debug                      Turn on Ruby debugging

  Arguments:
    GEMNAME       name of gem to download

  Summary:
    Download a gem and place it in the current directory

  Defaults:
    --version '>= 0'

You should be able to do

$ gem fetch gosu --platform x86-mswin32

Or simply go to the download page.

How to automatically download .gem files, including dependencies, and save .gem's to one folder?

Bundler has a great way to do this: bundle package.

http://bundler.io/v1.2/bundle_package.html

The package command will put all your gems in the bundle into ./vendor/cache. You can then do whatever you want with that directory, such as copying it to another machine, or checking it into version control, or torrenting it. etc.

Download all gems dependencies

Thats exactly the problem I had.

After searching around a while I found a Solution who works using Bundler https://bundler.io/

Getting Gem with Dependencies:

Create a new Folder with a File named Gemfile in it.
Write a Source and the Gem you want to have the dependencys for into the File
Example:
source "http://rubygems.org"

gem 'rails', '3.2.1'
Open a Commandline at this Folder an Execute: bundle install
This should download and install all Dependencys
Execute the Command bundle list if you wanna see it
Execute the Command bundle package
This should create the Directory Structure vendor/cache
Inside the cache Directory are now all the Dependencys you need for your gem

Install Gem on Machine without internet connection:

Copy the cache Folder to the Machine
Open a Commandline inside the Cache Folder and execute gem install --local Gemname.gem
Example:

gem install --local rails-3.2.1.gem

Is there a way to update RubyGems offline?

When you do gem install it will search the current directory before looking to the remote source. You must specify the version if you are installing a local gem (see rubygems manual).

gem install copland-0.2.0.gem

I'm sorry, I don't know a way to update the gem system offline without doing a manual upgrade

What is gem install bundler?

I dont have much knowledge of nodejs or java but can give you some idea.

Is it like npm for NodeJs and Maven for Java/J2EE

Yes, It is somewhat like that npm.Bundler helps to manage application dependency like xyz app requires foo bar gem. gem is like of libraries which extend the app functionality. This gems are primary located in rubygems.org server.

The first command i executed is gem install bundler. What is gem here and What is bundler, can some one enlighten me in terms of NodeJs or Maven.

when you do gem install <gem_name> , it creates a request to rubygems.org and download the repo(gem) and put it in the configured location. The location can be found in gem env command. To get the details of gem, you have to use gem install <gem_name> -d . So, when you are doing gem install bundler, you are installing bundler gem. This gem will help you to resolve/manage/install application dependencies. This is like npm install bundler with npm .

Where these getting installed?. I don't specify -g like i do in NodeJs for globally.

No, there is no need to write -g option here. My default, we install gems in one location which is not inside apps. personally i think transferring all those gems from one computer to another is slightly cumbersome, rather i prefer to run a command which automatically install all dependency. This is where bundler shines. Let say you have an app which requires foo , bar dependency since it uses its functionality. Without bundler, you have install this gems by running gem install foo , gem install bar. But with bundler, you will just do bundle install and you are done.

That's all. This will give you good start.

Why do I need to bundle install after every reboot in rails 3.2.1 with rvm?

If you're using Rails 3.2.1 with RVM, you usually do not need to run 'gem install' manually.

My guess is, you've installed ruby interpreter via RVM (or possibly, you haven't installed ruby in RVM), or you haven't configured RVM to select the default ruby interpreter.

You can configure default ruby by (if you're using 1.9.3-p0):

rvm 1.9.3-p0 --default

Then, the 1.9.3-p0 ruby will in effect after logging in to the shell. You can check which ruby interpreter is in use, by:

which ruby

If you correctly configured, it should be print like:

{your-home-path}/.rvm/rubies/ruby-1.9.3-p0/bin/ruby

In the post bundler-age rails app, you just need to run bundler to install required gems (onto the current gemset in RVM). If you don't create gemset, global gemset will be used. Run:

bundle

will install all gems you need.

Now, since RVM automatically select 1.9.3-p0 with gemset named 'global', you don't need to re-install after boot (as I do).

You can optionally create gemset for the rails app and configure per-directory basis. To configure default gemset/ruby interpreter per application, check the RVM site.