Ubuntu安装了ruby-dev，但仍然无法安装gem nokogiri

Question

I'm trying to install gem nokogiri by:

sudo gem install nokogiri

But I get this error:

ERROR:  Error installing nokogiri:
ERROR: Failed to build gem native extension.

current directory: /var/lib/gems/2.5.0/gems/nokogiri-1.8.4/ext/nokogiri
/usr/bin/ruby2.5 -r ./siteconf20181003-5678-1ub6p51.rb extconf.rb
mkmf.rb can't find header files for ruby at /usr/lib/ruby/include/ruby.h

I search on google and they said it because there are no ruby-dev. So I install ruby-dev by:

~$ sudo apt-get install ruby-dev
~$ dpkg -l | grep ruby-dev
ii  ruby-dev:amd64    2:2.3.0+1bbox1~xenial1         
      amd64        Header files for compiling extension modules for Ruby (default version)

And it install ruby-dev successfully but still get error before.

Answer 1

Thats the problem you dont have rails installed and also gem bundler. Can you please install it:

Run in terminal:

 gem install bundler

and after that:

gem install rails

Answer 2

install specific version of ruby

sudo apt-get install ruby2.5-dev

gem install nokogiri -v 1.8.4 -- --use-system-libraries