rbenv Install Ubuntu1804

published: 28th of January 2019

Intro

rbenv is a utility for installing multiple ruby versions on a host machine. Using rbenv allows you to install ruby in a path you have ownership over so you can install gems without having to have sudo or root privileges. rbenv also allows you to target the exact ruby version in development that's in use in production deployments potentially avoiding nefarious bugs due to Ruby version mismatches.

In this post I will install rbenv on Ubuntu 1804, install an alternate Ruby version to the system Ruby and cover some basic usage.

For reference the following software will be used in this post.

Ubuntu - 1804
rbenv - 1.1.1-39-g59785f6
ruby - 2.6.0

Dependencies

Install the required dependencies.

    cmd
  
    sudo apt-get install -y libssl-dev libreadline-dev

Install rbenv

Clone the rbenv git repository.

    cmd
  

    git clone https://github.com/rbenv/rbenv.git ~/.rbenv

# output

Cloning into '/home/vagrant/.rbenv'...
remote: Counting objects: 2744, done.
remote: Compressing objects: 100% (5/5), done.
remote: Total 2744 (delta 0), reused 5 (delta 0), pack-reused 2739
Receiving objects: 100% (2744/2744), 516.62 KiB | 867.00 KiB/s, done.
Resolving deltas: 100% (1717/1717), done.
  

Compile dynamic bash extension to speed up rbenv.

    cmd
  
    cd ~/.rbenv && src/configure && make -C src

# output

make: Entering directory '/home/vagrant/.rbenv/src'
gcc -fPIC     -c -o realpath.o realpath.c
gcc -shared -Wl,-soname,../libexec/rbenv-realpath.dylib  -o ../libexec/rbenv-realpath.dylib realpath.o
make: Leaving directory '/home/vagrant/.rbenv/src'

Update the ~/.bashrc to add the rbenv cli utility to your path.

    cmd
  
    echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.bashrc
echo 'eval "$(rbenv init -)"' >> ~/.bashrc

Reload your shell to load the rbenv parameters into the environment.

    cmd
  
    exec $SHELL -l

Install Plugins

Install the ruby-build plugin.

    cmd
  

    mkdir -p "$(rbenv root)"/plugins
git clone https://github.com/rbenv/ruby-build.git "$(rbenv root)"/plugins/ruby-build

# output

Cloning into '/home/vagrant/.rbenv/plugins/ruby-build'...
remote: Counting objects: 9159, done.
remote: Compressing objects: 100% (176/176), done.
remote: Total 9159 (delta 202), reused 82 (delta 62), pack-reused 8918
Receiving objects: 100% (9159/9159), 1.91 MiB | 99.00 KiB/s, done.
Resolving deltas: 100% (5920/5920), done.
  

Install Ruby

Install an alternate version of Ruby with the rbenv install <ruby-version> command.

    cmd
  
    rbenv install 2.6.0

# output

Downloading ruby-2.6.0.tar.bz2...
-> https://cache.ruby-lang.org/pub/ruby/2.4/ruby-2.6.0.tar.bz2
Installing ruby-2.6.0...
Installed ruby-2.6.0 to /home/vagrant/.rbenv/versions/2.6.0

After installing new version of Ruby or a gem that provides new commands, use the rbenv rehash command to install shims for all executables known to rbenv.

    cmd
  
    rbenv rehash

Usage

Create a project folder and set a default ruby version with the rbenv local <ruby-version> command.

    cmd
  
    mkdir ~/ruby-project && cd ~/ruby-project
rbenv local 2.6.0

Note

This will create a .ruby-version file in the project directory overriding the global Ruby version.

Confirm the Ruby version installed and location of the Ruby binary is in the users home directory.

    cmd
  
    ruby --version

# output

ruby 2.6.0p0 (2018-12-25 revision 66547) [x86_64-linux]

    cmd
  
    which ruby

# output

/home/vagrant/.rbenv/shims/ruby

    cmd
  
    which gem

# output

/home/vagrant/.rbenv/shims/gem

Confirm gems can be successfully installed as a non root user.

    cmd
  

    gem install bundler

# output

Fetching: bundler-2.0.1.gem (100%)
Successfully installed bundler-2.0.1
Parsing documentation for bundler-2.0.1
Installing ri documentation for bundler-2.0.1
Done installing documentation for bundler after 3 seconds
1 gem installed
  

    cmd
  
    which bundle

# output

/home/vagrant/.rbenv/shims/bundle

Outro

rbenv is a useful utility to managing multiple Ruby installs on a host machine. This allows you to keep your system Ruby install clean and also use the same Ruby version in your development environment as you would use in a production deployment.