Install ruby2.5-dev by entering the following commands in the terminal:
sudo apt update sudo apt install ruby2.5-dev
Description:
Header files for compiling extension modules for the Ruby 2.5
Ruby is the interpreted scripting language for quick and easy object-oriented programming. It has many features to process text files and to do system management tasks (as in perl). It is simple, straight-forward, and extensible. . This package contains the header files and the mkmf library, necessary to make extension library for Ruby 2.5. It is also required to build many gems.
Homepage: http://www.ruby-lang.org/
Version: 2.5.1-1ubuntu1
Section: ruby