ruby.rb

[root@localhost ~]# gem install fpm
Building native extensions.  This could take a while...
ERROR:  Error installing fpm:
	ERROR: Failed to build gem native extension.

    /usr/bin/ruby extconf.rb
mkmf.rb can't find header files for ruby at /usr/share/include/ruby.h


Gem files will remain installed in /usr/local/share/gems/gems/ffi-1.9.18 for inspection.
Results logged to /usr/local/share/gems/gems/ffi-1.9.18/ext/ffi_c/gem_make.out

[root@localhost ~]# yum list installed | egrep -i "ruby|gem|devel"
gettext-common-devel.noarch       0.18.2.1-4.el7             @rhel-7-server-rpms
gettext-devel.x86_64              0.18.2.1-4.el7             @rhel-7-server-rpms
glibc-devel.x86_64                2.17-106.el7_2.8           @rhel-7-server-rpms
kernel-devel.x86_64               3.10.0-327.36.3.el7        @rhel-7-server-rpms
libffi-devel.x86_64               3.0.13-16.el7              @rhel-7-server-rpms
libquadmath-devel.x86_64          4.8.5-4.el7                @rhel-7-server-rpms
libstdc++-devel.x86_64            4.8.5-4.el7                @rhel-7-server-rpms
ruby.x86_64                       2.0.0.598-25.el7_1         @rhel-7-server-rpms
ruby-irb.noarch                   2.0.0.598-25.el7_1         @rhel-7-server-rpms
ruby-libs.x86_64                  2.0.0.598-25.el7_1         @rhel-7-server-rpms
rubygem-bigdecimal.x86_64         1.2.0-25.el7_1             @rhel-7-server-rpms
rubygem-io-console.x86_64         0.4.2-25.el7_1             @rhel-7-server-rpms
rubygem-json.x86_64               1.7.7-25.el7_1             @rhel-7-server-rpms
rubygem-psych.x86_64              2.0.0-25.el7_1             @rhel-7-server-rpms
rubygem-rdoc.noarch               4.0.0-25.el7_1             @rhel-7-server-rpms
rubygems.noarch                   2.0.14-25.el7_1            @rhel-7-server-rpms
systemtap-devel.x86_64            2.8-10.el7                 @rhel-7-server-rpms