Ruby gems can be broadly divided into
- System gems. CLIs, linters, scripts, an so on, meant to be run as part of the system.
- Library gems. Libraries, toolbox, and frameworks meant to be used in code.
System gems
Given a local box with Ruby’s default, and bundle gems, as well as a few system gems.
$ gem outdated
$ gem update
$ gem cleanup -d
The -d flag, in the last command, stands for dry run. Which invokes the command without removing any old gem merely to show what we can expect if we run it without the flag.
Rubygems
To update Rubygems, as in the CLI, to the latest version
$ gem update --system
Library gems
Nowadays, Ruby projects are expected to manage dependencies with bundler, via a Gemfile (from 2.5, it could be gems.rb instead). Assuming the rake command runs all tests, we can update a project’s dependencies with:
$ rake
# update gem version in Gemfile
$ bundle install
$ rake
To prevent introducing bugs massively due to broken APIs, or any other conflicts, upgrade each gem individually. Occasionally group upgrade is needed ie. gem with plugins. Once done upgrading all new gems:
$ bundle clean --dry-run
$ bundle clean
Consider subscribing to the RSS feed of a project’s main gems to keep up-to-date with security patches, and other fixes. We can subscribe to any ruby gem feed with the formula:
https://rubygems.org/gems/<gem_name>/versions.atom