Base de connaissances

Ruby powers Ruby on Rails applications and various automation scripts. This guide covers installing Ruby via rbenv, letting you manage multiple Ruby versions per project cleanly.

Prerequisites

• Ubuntu 22.04/24.04 or Debian 11/12 VPS
• Root or sudo access

Step 1 — Install Build Dependencies

sudo apt update
sudo apt install git curl libssl-dev libreadline-dev zlib1g-dev \
  autoconf bison build-essential libyaml-dev libncurses5-dev \
  libffi-dev libgdbm-dev -y

Step 2 — Install rbenv

git clone https://github.com/rbenv/rbenv.git ~/.rbenv
echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.bashrc
echo 'eval "$(rbenv init -)"' >> ~/.bashrc
source ~/.bashrc

Step 3 — Install the ruby-build Plugin

git clone https://github.com/rbenv/ruby-build.git ~/.rbenv/plugins/ruby-build

Step 4 — List Available Ruby Versions

rbenv install -l

Step 5 — Install a Ruby Version

rbenv install 3.3.5

This compiles Ruby from source and can take several minutes.

Step 6 — Set the Global Default Version

rbenv global 3.3.5

Step 7 — Verify Installation

ruby -v

Setting a Per-Project Version

cd myproject
rbenv local 3.2.4

This creates a .ruby-version file in the project directory, automatically switching versions whenever you're in that folder.

Step 8 — Install Bundler (Ruby's Dependency Manager)

gem install bundler
rbenv rehash

Installing Rails (If Building a Rails Application)

gem install rails
rbenv rehash

Installing Project Dependencies

cd myproject
bundle install

Common Errors

"rbenv: command not found" — the shell profile wasn't reloaded correctly; verify the export lines were added to ~/.bashrc and re-source it.

Compilation fails during rbenv install — almost always a missing build dependency; re-run Step 1 to confirm all required packages are installed.

"command not found" after installing a gem with an executable — run rbenv rehash to refresh rbenv's shim links after installing new gems.

Best Practices

• Use rbenv local per project rather than relying solely on the global version
• Commit Gemfile.lock to version control for reproducible installs
• Run rbenv rehash after installing any gem that provides a command-line executable

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