❯ jekyll serve
Configuration file: /Users/mh/workspaces/myeong-han.github.io/_config.yml
            Source: /Users/mh/workspaces/myeong-han.github.io
       Destination: /Users/mh/workspaces/myeong-han.github.io/_site
 Incremental build: disabled. Enable with --incremental
      Generating...
                    done in 0.266 seconds.
 Auto-regeneration: enabled for '/Users/mh/workspaces/myeong-han.github.io'
/Users/mh/.gem/ruby/3.1.3/gems/jekyll-3.9.3/lib/jekyll/commands/serve/servlet.rb:3:in `require': cannot load such file -- webrick (LoadError)
	from /Users/mh/.gem/ruby/3.1.3/gems/jekyll-3.9.3/lib/jekyll/commands/serve/servlet.rb:3:in `<top (required)>'
	from /Users/mh/.gem/ruby/3.1.3/gems/jekyll-3.9.3/lib/jekyll/commands/serve.rb:184:in `require_relative'
	from /Users/mh/.gem/ruby/3.1.3/gems/jekyll-3.9.3/lib/jekyll/commands/serve.rb:184:in `setup'
	from /Users/mh/.gem/ruby/3.1.3/gems/jekyll-3.9.3/lib/jekyll/commands/serve.rb:102:in `process'
	from /Users/mh/.gem/ruby/3.1.3/gems/jekyll-3.9.3/lib/jekyll/commands/serve.rb:93:in `block in start'
	from /Users/mh/.gem/ruby/3.1.3/gems/jekyll-3.9.3/lib/jekyll/commands/serve.rb:93:in `each'
	from /Users/mh/.gem/ruby/3.1.3/gems/jekyll-3.9.3/lib/jekyll/commands/serve.rb:93:in `start'
	from /Users/mh/.gem/ruby/3.1.3/gems/jekyll-3.9.3/lib/jekyll/commands/serve.rb:75:in `block (2 levels) in init_with_program'
	from /Users/mh/.gem/ruby/3.1.3/gems/mercenary-0.3.6/lib/mercenary/command.rb:220:in `block in execute'
	from /Users/mh/.gem/ruby/3.1.3/gems/mercenary-0.3.6/lib/mercenary/command.rb:220:in `each'
	from /Users/mh/.gem/ruby/3.1.3/gems/mercenary-0.3.6/lib/mercenary/command.rb:220:in `execute'
	from /Users/mh/.gem/ruby/3.1.3/gems/mercenary-0.3.6/lib/mercenary/program.rb:42:in `go'
	from /Users/mh/.gem/ruby/3.1.3/gems/mercenary-0.3.6/lib/mercenary.rb:19:in `program'
	from /Users/mh/.gem/ruby/3.1.3/gems/jekyll-3.9.3/exe/jekyll:15:in `<top (required)>'
	from /Users/mh/.gem/ruby/3.1.3/bin/jekyll:25:in `load'
	from /Users/mh/.gem/ruby/3.1.3/bin/jekyll:25:in `<main>'

# Gemfile에 부족한 dependency 추가
bundle add webrick

$ jekyll

-bash: jekyll: command not found

- RUBYGEMS VERSION: 1.3.4
  - RUBY VERSION: 1.8.7 (2010-01-10 patchlevel 249) [universal-darwin10.0]
  - INSTALLATION DIRECTORY: /Volumes/HDD/DADU/gems
  - RUBY EXECUTABLE: /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby
  - EXECUTABLE DIRECTORY: /Volumes/HDD/DADU/gems/bin
  - RUBYGEMS PLATFORMS:
    - ruby
    - universal-darwin-10
  - GEM PATHS:
     - /Volumes/HDD/DADU/gems
     - /Volumes/HDD/DADU/.gem/ruby/1.8
     - /Library/Ruby/Gems/1.8
     - /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8
  - GEM CONFIGURATION:
     - :update_sources => true
     - :verbose => true
     - :benchmark => false
     - :backtrace => false
     - :bulk_threshold => 1000
  - REMOTE SOURCES:
     - http://gems.rubyforge.org/