Which ruby version am I using — how to check?

Are you not sure which Ruby version you are using right now? Wondering how to check it? Say no more. Here are two simple ways to check for it.

In irb

Run irb and type:

RUBY_VERSION
# => "2.4.1"

From command line

Just type ruby -v

$ ruby -v
ruby 2.4.1p111 (2017-03-22 revision 58053) [x86_64-linux]

In RVM

Are you using RVM?

Run rvm current and get the answer

$ rvm current
ruby-2.4.1

In rbenv

Are you using rbenv? Just run rbenv version

$ rbenv version
2.4.1p111 (set by /Users/rupert/.rbenv/version)

Using which

Do you want to know where your ruby binary is installed? It can also sometimes reveal the version you are using as it is usually part of directory structure. Just run which ruby.

$ which ruby
/home/rupert/.rvm/rubies/ruby-2.4.1/bin/ruby

Using gem env

If you want to know even more about your current ruby setup, there is a command for that as well!

$ gem env
RubyGems Environment:
  - RUBYGEMS VERSION: 2.6.12
  - RUBY VERSION: 2.4.1 (2017-03-22 patchlevel 111) [x86_64-linux]
  - INSTALLATION DIRECTORY: /home/rupert/.rvm/gems/ruby-2.4.1
  - USER INSTALLATION DIRECTORY: /home/rupert/.gem/ruby/2.4.0
  - RUBY EXECUTABLE: /home/rupert/.rvm/rubies/ruby-2.4.1/bin/ruby
  - EXECUTABLE DIRECTORY: /home/rupert/.rvm/gems/ruby-2.4.1/bin
  - SPEC CACHE DIRECTORY: /home/rupert/.gem/specs
  - SYSTEM CONFIGURATION DIRECTORY: /etc
  - RUBYGEMS PLATFORMS:
    - ruby
    - x86_64-linux
  - GEM PATHS:
     - /home/rupert/.rvm/gems/ruby-2.4.1
     - /home/rupert/.rvm/gems/ruby-2.4.1@global
  - GEM CONFIGURATION:
     - :update_sources => true
     - :verbose => true
     - :backtrace => false
     - :bulk_threshold => 1000
     - "gem" => "--no-document"
  - REMOTE SOURCES:
     - https://rubygems.org/