hi
my persian keyboard language not working now so i sending this question with english language.
when i want to install wpscan with gem command in ubuntu system i get this error and wpscan not installed
# gem install wpscan
Fetching: mini_portile2-2.4.0.gem (100%)
Successfully installed mini_portile2-2.4.0
Fetching: nokogiri-1.10.3.gem (100%)
Building native extensions. This could take a while...
ERROR: Error installing wpscan:
ERROR: Failed to build gem native extension.
current directory: /var/lib/gems/2.5.0/gems/nokogiri-1.10.3/ext/nokogiri
/usr/bin/ruby2.5 -r ./siteconf20190628-3740-sij5d9.rb extconf.rb
mkmf.rb can't find header files for ruby at /usr/lib/ruby/include/ruby.h
extconf failed, exit code 1
Gem files will remain installed in /var/lib/gems/2.5.0/gems/nokogiri-1.10.3 for inspection.
Results logged to /var/lib/gems/2.5.0/extensions/x86_64-linux/2.5.0/nokogiri-1.10.3/gem_make.out
whats problem?