List All Installable Rails Versions

Here's a screencast in case you want to watch instead of read.

I was curious what versions of Rails were remotely available to be installed with gem. On its own, gem list rails will show all locally installed gems that partially match rails. That'll include gems like rspec-rails and sprockets-rails.

First, the --exact flag can be added to narrow down the results to an exact match of rails.

Then, the --remote flag can be included to request gem look for remote versions. That is, versions available on the rubygems server.

Lastly, the --all flag can be included to fetch all versions instead of only the latest version.

Putting it all together:

$ gem list rails --exact --remote --all
rails (6.1.0, 6.0.3.4, 6.0.3.3, ... 0.9.0, 0.8.5, 0.8.0)

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