Ruby version management (rbenv, rvm) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of Ruby version managers like rbenv and rvm?

They help you install and switch between different Ruby versions easily on the same computer, so you can work on projects that need different Ruby versions without conflicts.

intermediate

How does rbenv switch Ruby versions for your projects?

rbenv changes the Ruby version by adjusting your shell's PATH to point to the selected Ruby version's executables, letting you pick a global or project-specific Ruby version.

beginner

What command do you use to install a new Ruby version with rvm?

You use rvm install <version>, for example, rvm install 3.1.2 to install Ruby version 3.1.2.

intermediate

How can you set a Ruby version only for a specific project using rbenv?

Inside the project folder, run rbenv local <version>. This creates a .ruby-version file that tells rbenv to use that Ruby version only when you are in that folder.

intermediate

What is a key difference between rbenv and rvm?

rvm is a full Ruby environment manager that can also manage gemsets, while rbenv focuses mainly on switching Ruby versions and relies on other tools for gem management.

Which command installs Ruby version 3.0.0 using rbenv?

A gem install 3.0.0

B rvm install 3.0.0

C ruby install 3.0.0

D rbenv install 3.0.0

rbenv uses 'rbenv install ' to install Ruby versions.

How do you switch the global Ruby version with rvm?

A rvm use 3.1.0 --default

B rbenv global 3.1.0

C ruby switch 3.1.0

D gem switch 3.1.0

With rvm, 'rvm use --default' sets the global Ruby version.

What file does rbenv create to remember the Ruby version for a project?

A .ruby-version

B Gemfile

C .rvmrc

D ruby.env

rbenv creates a '.ruby-version' file in the project folder to set the local Ruby version.

Which Ruby version manager supports gemsets natively?

A chruby

B rbenv

C rvm

D rake

rvm supports gemsets, which let you isolate gems per project.

If you want to try a new Ruby version temporarily with rbenv, which command do you use?

A rbenv global <version>

B rbenv shell <version>

C rvm use <version>

D ruby switch <version>

'rbenv shell ' sets the Ruby version only for the current terminal session.

Explain how rbenv helps manage different Ruby versions on your computer.

Think about how your computer knows which Ruby to run.

Describe the main differences between rbenv and rvm and when you might choose one over the other.

Consider what extra features you need besides just switching Ruby versions.

Practice

1. What is the main purpose of using Ruby version managers like rbenv or rvm?

easy

A. To debug Ruby code automatically

B. To write Ruby code faster

C. To compile Ruby programs into executables

D. To switch between different Ruby versions easily

Solution

1. Step 1: Understand Ruby version managers

   Ruby version managers like rbenv and rvm allow you to install and switch between multiple Ruby versions on the same machine.

2. Step 2: Identify the main use

   The main use is to switch Ruby versions easily without affecting other projects or the system Ruby.

3. Final Answer:

   To switch between different Ruby versions easily -> Option D

4. Quick Check:

   Ruby version managers help switch versions = D [OK]

Hint: Remember: rbenv and rvm manage Ruby versions [OK]

Common Mistakes:

• Thinking they speed up coding
• Confusing with debugging tools
• Assuming they compile Ruby code

2. Which of the following commands correctly sets the global Ruby version to 3.1.2 using rbenv?

easy

A. rbenv global 3.1.2

B. rbenv use 3.1.2

C. rbenv set 3.1.2

D. rbenv switch 3.1.2

Solution

1. Step 1: Recall rbenv commands

   The command to set the global Ruby version in rbenv is rbenv global <version>.

2. Step 2: Match the correct command

   Among the options, only rbenv global 3.1.2 correctly sets the global version.

3. Final Answer:

   rbenv global 3.1.2 -> Option A

4. Quick Check:

   Set global version = rbenv global [OK]

Hint: Use 'rbenv global' to set Ruby version globally [OK]

Common Mistakes:

• Using 'rbenv use' which is invalid
• Confusing 'set' or 'switch' commands
• Not specifying the version number

3. Given the following commands run in order:
rbenv install 3.0.0
rbenv local 3.0.0
ruby -v
What will be the output of ruby -v?

medium

A. ruby 2.7.0 (system default)

B. Command not found error

C. ruby 3.0.0 (installed version)

D. ruby 3.1.0 (latest version)

Solution

1. Step 1: Understand the commands

   rbenv install 3.0.0 installs Ruby 3.0.0. rbenv local 3.0.0 sets the Ruby version to 3.0.0 for the current directory.

2. Step 2: Predict the ruby version output

   Running ruby -v in that directory will use Ruby 3.0.0, showing its version.

3. Final Answer:

   ruby 3.0.0 (installed version) -> Option C

4. Quick Check:

   Local version set to 3.0.0 means ruby -v shows 3.0.0 [OK]

Hint: Local version overrides system Ruby version [OK]

Common Mistakes:

• Assuming system default Ruby is used
• Expecting latest Ruby version output
• Thinking command will fail without global set

4. You run rvm use 2.7.0 but get the error: RVM is not a function, selecting rubies with 'rvm use ...' will not work.
What is the most likely cause?

medium

A. RVM is not installed

B. You did not load RVM as a shell function

C. Ruby 2.7.0 is not installed

D. You need to restart your computer

Solution

1. Step 1: Understand the error message

   The error says 'RVM is not a function', which means the shell does not recognize RVM commands properly.

2. Step 2: Identify cause

   This usually happens if the RVM script is not sourced in the shell, so RVM commands are not loaded as functions.

3. Final Answer:

   You did not load RVM as a shell function -> Option B

4. Quick Check:

   Load RVM script in shell to fix 'not a function' error [OK]

Hint: Always source RVM script in your shell config [OK]

Common Mistakes:

• Assuming RVM is not installed at all
• Thinking Ruby version is missing
• Restarting computer unnecessarily

5. You want to create a project that uses Ruby 3.2.0 but your system default is Ruby 2.6.3. Using rbenv, which sequence of commands correctly sets up your project to use Ruby 3.2.0 locally without affecting other projects?

hard

A. rbenv install 3.2.0rbenv local 3.2.0

B. rbenv local 3.2.0rbenv install 3.2.0

C. rbenv install 3.2.0rbenv global 3.2.0

D. rbenv global 3.2.0rbenv install 3.2.0

Solution

1. Step 1: Install Ruby 3.2.0 first

   You must install Ruby 3.2.0 before using it. So rbenv install 3.2.0 is first.

2. Step 2: Set local version for project

   To use Ruby 3.2.0 only in the project folder, use rbenv local 3.2.0. This does not affect other projects or the global version.

3. Final Answer:

   rbenv install 3.2.0
   rbenv local 3.2.0 -> Option A

4. Quick Check:

   Install then set local version for project isolation [OK]

Hint: Install Ruby first, then set local version for project [OK]

Common Mistakes:

• Setting global version instead of local
• Setting local version before installing Ruby
• Assuming global affects only one project