Ruby version management (rbenv, rvm) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this rbenv command?

You run the command rbenv versions after installing Ruby 3.1.2 and 2.7.6. What output will you see?

Ruby

$ rbenv versions
  system
* 3.1.2 (set by /home/user/.rbenv/version)
  2.7.6

A

  system
* 3.1.2 (set by /home/user/.rbenv/version)
  2.7.6

B

* 3.1.2
  2.7.6
  system

C

3.1.2
2.7.6
system

D No versions installed

💡 Hint

The asterisk (*) marks the currently active Ruby version.

The rbenv versions command lists installed Ruby versions. The active version is marked with an asterisk and shows the file that sets it.

❓ Predict Output

intermediate

What happens when you run rvm use 2.6.5 if Ruby 2.6.5 is not installed?

You run rvm use 2.6.5 but Ruby 2.6.5 is not installed on your system. What will be the result?

Ruby

rvm use 2.6.5

A RVM will uninstall all Ruby versions.

B RVM will automatically download and install Ruby 2.6.5, then switch to it.

C RVM will switch to the system Ruby version instead.

D RVM will show an error: 'Unknown ruby interpreter or version: 2.6.5'.

💡 Hint

The plain `rvm use` command requires the version to be installed first; use `rvm install` separately.

RVM's `rvm use` command switches to an already installed Ruby version. If not installed, it shows an error like 'ruby-2.6.5 is not installed'.

🔧 Debug

advanced

Why does ruby -v show a different version than rbenv version?

You set Ruby 3.0.0 as global with rbenv global 3.0.0, but running ruby -v shows Ruby 2.7.0. What is the most likely cause?

A Your shell environment does not have <code>rbenv</code> initialized in PATH.

B You forgot to run <code>rbenv rehash</code> after installing Ruby 3.0.0.

C Ruby 3.0.0 is not installed at all.

D You need to uninstall Ruby 2.7.0 manually.

💡 Hint

Check if rbenv commands are recognized and PATH is set correctly.

If rbenv is not initialized in your shell PATH, the system Ruby will be used instead of the selected version.

📝 Syntax

advanced

Which command correctly sets a local Ruby version with rbenv?

You want to set Ruby 3.2.0 only for the current project directory. Which command is correct?

A rbenv use 3.2.0

B rbenv global 3.2.0

C rbenv local 3.2.0

D rbenv set 3.2.0

💡 Hint

Local version affects only the current directory and subdirectories.

The rbenv local command writes the version to a .ruby-version file in the current directory.

🚀 Application

expert

How to ensure a Ruby script uses a specific Ruby version with rvm in a CI pipeline?

You want your CI pipeline to run a Ruby script using Ruby 2.7.4 managed by RVM, without affecting other jobs. Which is the best approach?

A Install Ruby 2.7.4 globally on the CI machine and run the script directly.

B Add <code>rvm use 2.7.4 --install --binary --fuzzy</code> before running the script.

C Use <code>rbenv local 2.7.4</code> in the CI script before running Ruby.

D Set the environment variable <code>RUBY_VERSION=2.7.4</code> and run the script.

💡 Hint

RVM can install and switch Ruby versions on the fly in scripts.

Using rvm use 2.7.4 --install --binary --fuzzy ensures Ruby 2.7.4 is installed if missing and switches to it only for that session.