I am a novice with ruby and the command line.

**Ruby -v:** ruby 2.3.7p456 (2018-03-28 revision 63024) [universal.x86\_64-darwin18]

**Mac:** Mojave 10.14.2

I am trying to open my Jekyll blog on my localhost, something which hasn't given me issues previously. However I ran

```
bundle exec jekyll serve

```

and get this error:

```
Could not find eventmachine-1.2.7 in any of the sources
Run `bundle install` to install missing gems.

```

As suggested, I then run

```
bundle install

```

and get this error:

```
    Ignoring ffi-1.9.25 because its extensions are not built.  Try: gem pristine ffi --version 1.9.25
Ignoring http_parser.rb-0.6.0 because its extensions are not built.  Try: gem pristine http_parser.rb --version 0.6.0
Fetching gem metadata from https://rubygems.org/...........
Using rake 10.5.0
Using public_suffix 3.0.3
Using addressable 2.5.2
Using bundler 2.0.1
Using colorator 1.1.0
Using concurrent-ruby 1.0.5
Fetching eventmachine 1.2.7
Installing eventmachine 1.2.7 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    current directory: /Users/name/Desktop/GitHub/blog/vendor/bundle/ruby/2.3.0/gems/eventmachine-1.2.7/ext
/System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/bin/ruby -r ./siteconf20190212-57509-l19d0i.rb extconf.rb
--with-cppflags=-I/usr/local/opt/openssl/include
checking for main() in -lcrypto... *** 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/$(RUBY_BASE_NAME)
    --with-ssl-dir
    --without-ssl-dir
    --with-ssl-include
    --without-ssl-include=${ssl-dir}/include
    --with-ssl-lib
    --without-ssl-lib=${ssl-dir}/lib
    --with-openssl-config
    --without-openssl-config
    --with-pkg-config
    --without-pkg-config
    --with-cryptolib
    --without-cryptolib
/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:535:in `block in try_link0'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/2.3.0/tmpdir.rb:89:in `mktmpdir'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/2.3.0/mkmf.rb:532:in `try_link0'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/2.3.0/mkmf.rb:556:in `try_link'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/2.3.0/mkmf.rb:765:in `try_func'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/2.3.0/mkmf.rb:997:in `block in have_library'
    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:992:in `have_library'
    from extconf.rb:8:in `block in check_libs'
    from extconf.rb:8:in `each'
    from extconf.rb:8:in `all?'
    from extconf.rb:8:in `check_libs'
    from extconf.rb:95:in `<main>'

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

/Users/name/Desktop/GitHub/blog/vendor/bundle/ruby/2.3.0/extensions/universal-darwin-18/2.3.0/eventmachine-1.2.7/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in
/Users/nbame/Desktop/GitHub/blog/vendor/bundle/ruby/2.3.0/gems/eventmachine-1.2.7 for inspection.
Results logged to
/Users/name/Desktop/GitHub/blog/vendor/bundle/ruby/2.3.0/extensions/universal-darwin-18/2.3.0/eventmachine-1.2.7/gem_make.out

An error occurred while installing eventmachine (1.2.7), and Bundler cannot continue.
Make sure that `gem install eventmachine -v '1.2.7' --source 'https://rubygems.org/'` succeeds before bundling.

In Gemfile:
  jekyll was resolved to 3.8.3, which depends on
    em-websocket was resolved to 0.5.1, which depends on
      eventmachine

```

I have tried:

* Using **gem install eventmachine -v '1.2.7' --source '<https://rubygems.org/>'** which gives me the "ERROR: Failed to build gem native extension."
* **brew install coreutils** as recommended [here](https://stackoverflow.com/questions/37602947/bcrypt-ruby-3-1-2-gemextbuilderror-error-failed-to-build-gem-native-extens)
* Every answer to [this question](https://stackoverflow.com/questions/30818391/gem-eventmachine-fatal-error-openssl-ssl-h-file-not-found)
* The answers [here](https://stackoverflow.com/questions/52514791/after-upgrading-to-macos-mojave-gem-update-is-failing) relating to Mojave and gem update failing
* **gem pristine ffi --version 1.9.25** because it suggested so in the error message

My mkmf.log log is below

```
"xcrun clang -o conftest -I/System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/include/ruby-2.3.0/universal-darwin18 -I/System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/include/ruby-2.3.0/ruby/backward -I/System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/include/ruby-2.3.0 -I. -I/usr/local/opt/openssl/include  -g -Os -pipe -DHAVE_GCC_ATOMIC_BUILTINS conftest.c  -L. -L/System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib -L.     -lruby.2.3.0  -lpthread -ldl -lobjc "
In file included from conftest.c:1:
In file included from /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/include/ruby-2.3.0/ruby.h:33:
/System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/include/ruby-2.3.0/ruby/ruby.h:24:10: fatal error: 'ruby/config.h' file not found
#include "ruby/config.h"
         ^~~~~~~~~~~~~~~
1 error generated.
checked program was:
/* begin */
1: #include "ruby.h"
2: 
3: int main(int argc, char **argv)
4: {
5:   return 0;
6: }
/* end */

"pkg-config --exists openssl"
package configuration for openssl is not found

```