下記がError文になります。
sudo gem install compass -n /usr/local/bin/
上記等色々試したのですがインストール出来ず。。。
ご教授頂けると幸いです。

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MacBook-Pro:~ WEB20-150129$ sudo gem install compass
Password:
Building native extensions. This could take a while...
ERROR:  Error installing compass:
    ERROR: Failed to build gem native extension.

    current directory: /Library/Ruby/Gems/2.3.0/gems/ffi-1.9.25/ext/ffi_c
/System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/bin/ruby -r ./siteconf20180929-7168-fcft1p.rb extconf.rb
checking for ffi.h... *** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
    --with-opt-dir
    --without-opt-dir
    --with-opt-include
    --without-opt-include=${opt-dir}/include
    --with-opt-lib
    --without-opt-lib=${opt-dir}/lib
    --with-make-prog
    --without-make-prog
    --srcdir=.
    --curdir
    --ruby=/System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/bin/$(RUBY_BASE_NAME)
    --with-ffi_c-dir
    --without-ffi_c-dir
    --with-ffi_c-include
    --without-ffi_c-include=${ffi_c-dir}/include
    --with-ffi_c-lib
    --without-ffi_c-lib=${ffi_c-dir}/lib
    --with-libffi-config
    --without-libffi-config
    --with-pkg-config
    --without-pkg-config
/System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/2.3.0/mkmf.rb:456:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
    from /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/2.3.0/mkmf.rb:571:in `block in try_compile'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/2.3.0/mkmf.rb:524:in `with_werror'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/2.3.0/mkmf.rb:571:in `try_compile'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/2.3.0/mkmf.rb:1091:in `block in have_header'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/2.3.0/mkmf.rb:942:in `block in checking_for'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/2.3.0/mkmf.rb:350:in `block (2 levels) in postpone'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/2.3.0/mkmf.rb:320:in `open'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/2.3.0/mkmf.rb:350:in `block in postpone'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/2.3.0/mkmf.rb:320:in `open'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/2.3.0/mkmf.rb:346:in `postpone'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/2.3.0/mkmf.rb:941:in `checking_for'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/2.3.0/mkmf.rb:1090:in `have_header'
    from extconf.rb:16:in `<main>'

To see why this extension failed to compile, please check the mkmf.log which can be found here:

  /Library/Ruby/Gems/2.3.0/extensions/universal-darwin-18/2.3.0/ffi-1.9.25/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in /Library/Ruby/Gems/2.3.0/gems/ffi-1.9.25 for inspection.
Results logged to /Library/Ruby/Gems/2.3.0/extensions/universal-darwin-18/2.3.0/ffi-1.9.25/gem_make.out

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