CLI gem install fails

[conspacer]

hi @mtuckergd . This is an interesting project, esp, being able to export private channels in Slack. Are you maintaining this project?
If so, Ill output some feedback on an install fail.
If not, disregard and have a nice day :)

[mtuckergh]

Hi! I would say "maintaining" is a very loose term, but if you can give me repro steps on your install problem I can certainly try to take a look at it.
Thanks for your interest!

[conspacer]

System: Debian 'Jessie' x64 (headless)

Command
sudo gem install slack_export

Output

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

    /usr/bin/ruby2.1 mkrf_conf.rb
Building native extensions.  This could take a while... 
/usr/lib/ruby/2.1.0/rubygems/ext/builder.rb:89:in `run': ERROR: Failed to build gem native extension. (Gem::Ext::BuildError) 
    /usr/bin/ruby2.1 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/2.1.0/gems/unf-0.2.0.beta2/ext/gems/gems/unf_ext-0.0.7.2 for inspection.
Results logged to /var/lib/gems/2.1.0/gems/unf-0.2.0.beta2/ext/gems/extensions/x86_64-linux/2.1.0/unf_ext-0.0.7.2/gem_make.out 
        from /usr/lib/ruby/2.1.0/rubygems/ext/ext_conf_builder.rb:38:in `block in build'
        from /usr/lib/ruby/2.1.0/tempfile.rb:324:in `open'                              
        from /usr/lib/ruby/2.1.0/rubygems/ext/ext_conf_builder.rb:17:in `build'         
        from /usr/lib/ruby/2.1.0/rubygems/ext/builder.rb:161:in `block (2 levels) in build_extension'
        from /usr/lib/ruby/2.1.0/rubygems/ext/builder.rb:160:in `chdir'                 
        from /usr/lib/ruby/2.1.0/rubygems/ext/builder.rb:160:in `block in build_extension'
        from /usr/lib/ruby/2.1.0/rubygems/ext/builder.rb:159:in `synchronize' 
        from /usr/lib/ruby/2.1.0/rubygems/ext/builder.rb:159:in `build_extension'
        from /usr/lib/ruby/2.1.0/rubygems/ext/builder.rb:198:in `block in build_extensions' 
        from /usr/lib/ruby/2.1.0/rubygems/ext/builder.rb:195:in `each' 
        from /usr/lib/ruby/2.1.0/rubygems/ext/builder.rb:195:in `build_extensions' 
        from /usr/lib/ruby/2.1.0/rubygems/installer.rb:677:in `build_extensions' 
        from /usr/lib/ruby/2.1.0/rubygems/installer.rb:232:in `install'  
        from /usr/lib/ruby/2.1.0/rubygems/resolver/specification.rb:78:in `install' 
        from /usr/lib/ruby/2.1.0/rubygems/request_set.rb:206:in `block in install_into' 
        from /usr/lib/ruby/2.1.0/rubygems/request_set.rb:198:in `each'                  
        from /usr/lib/ruby/2.1.0/rubygems/request_set.rb:198:in `install_into'          
        from /usr/lib/ruby/2.1.0/rubygems/request_set.rb:119:in `install'               
        from /usr/lib/ruby/2.1.0/rubygems/dependency_installer.rb:389:in `install'      
        from mkrf_conf.rb:15:in `<main>' 

rake failed, exit code 1 

Gem files will remain installed in /var/lib/gems/2.1.0/gems/unf-0.2.0.beta2 for inspection.
Results logged to /var/lib/gems/2.1.0/extensions/x86_64-linux/2.1.0/unf-0.2.0.beta2/gem_make.out