[root@localhost ~]# gem install mysql2

Building native extensions. This could take a while... ERROR: Error installing mysql2: ERROR: Failed to build gem native extension.

current directory: /usr/local/share/gems/gems/mysql2-0.5.2/ext/mysql2 /usr/bin/ruby -r ./siteconf20180727-4443-m9s83b.rb extconf.rb mkmf.rb can't find header files for ruby at /usr/share/include/ruby.h

extconf failed, exit code 1

Gem files will remain installed in /usr/local/share/gems/gems/mysql2-0.5.2 for inspection. Results logged to /usr/local/lib64/gems/ruby/mysql2-0.5.2/gem_make.out [root@localhost ~]# gem install mysql2 -v 0.5.1 Fetching: mysql2-0.5.1.gem (100%) Building native extensions. This could take a while... ERROR: Error installing mysql2: ERROR: Failed to build gem native extension.

current directory: /usr/local/share/gems/gems/mysql2-0.5.1/ext/mysql2 /usr/bin/ruby -r ./siteconf20180727-4452-1pfveel.rb extconf.rb mkmf.rb can't find header files for ruby at /usr/share/include/ruby.h

extconf failed, exit code 1

Gem files will remain installed in /usr/local/share/gems/gems/mysql2-0.5.1 for inspection. Results logged to /usr/local/lib64/gems/ruby/mysql2-0.5.1/gem_make.out