ruby GEM_HOME 和 GEM_PATH 有什么区别？
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What's the difference between GEM_HOME and GEM_PATH?
提问by Michiel de Mare
RubyGems is a package manager for the Ruby programming language that provides a standard format for distributing Ruby programs and libraries (in a self-contained format called a "gem"), a tool designed to easily manage the installation of gems, and a server for distributing them. It is analogous to EasyInstall for the Python programming language. RubyGems is now part of the standard library from Ruby version 1.9.
RubyGems 是 Ruby 编程语言的包管理器，它提供了用于分发 Ruby 程序和库的标准格式（以称为“gem”的自包含格式）、旨在轻松管理 gems 安装的工具以及用于分发它们。它类似于 Python 编程语言的 EasyInstall。RubyGems 现在是 Ruby 1.9 版标准库的一部分。
That said, what's the difference between GEM_HOME and GEM_PATH?
也就是说， GEM_HOME 和 GEM_PATH 之间有什么区别？
回答by Michiel de Mare
GEM_PATH provides the locations (there may be several) where gems can be found.
GEM_PATH 提供了可以找到宝石的位置（可能有几个）。
GEM_HOME is where gems will be installed (by default).
GEM_HOME 是安装 gem 的地方（默认情况下）。
(Therefore GEM_PATH should include GEM_HOME).
（因此 GEM_PATH 应该包括 GEM_HOME）。
回答by Green
Also interesting notice. At least on Wndows XP, don't know about other platforms.
还有有趣的通知。至少在 Wndows XP 上，不知道其他平台。
Set GEM_HOMEin Windows:
GEM_HOME在 Windows 中设置：
C:\>set GEM_HOME=C:\sbox\ruby\dump\.gems
Now let's check this.
现在让我们检查一下。
1) In Windows ENVs. All OK, as expected:
1) 在 Windows 环境中。一切正常，正如预期的那样：
C:\>set
...
GEM_HOME=C:\sbox\ruby\dump\.gems
...
2) With gem env. Notice it puts GEM_HOMEalong with GEM_PATHs but at the first place:
2) 与gem env。请注意，它GEM_HOME与GEM_PATHs放在一起，但首先是：
C:\>gem env
RubyGems Environment:
- RUBYGEMS VERSION: 2.0.3
- RUBY VERSION: 2.0.0 (2013-02-24 patchlevel 0) [i386-mingw32]
- INSTALLATION DIRECTORY: C:/sbox/ruby/dump/.gems
- RUBY EXECUTABLE: C:/Ruby200/bin/ruby.exe
- EXECUTABLE DIRECTORY: C:/sbox/ruby/dump/.gems/bin
- RUBYGEMS PLATFORMS:
- ruby
- x86-mingw32
- GEM PATHS:
- C:/sbox/ruby/dump/.gems
- C:/Documents and Settings/User/.gem/ruby/2.0.0
- C:/Ruby200/lib/ruby/gems/2.0.0
- GEM CONFIGURATION:
- :update_sources => true
- :verbose => true
- :backtrace => false
- :bulk_threshold => 1000
- REMOTE SOURCES:
- https://rubygems.org/
3) Now with bundle env:
3）现在bundle env：
C:\>bundle env
Bundler 1.3.4
Ruby 2.0.0 (2013-02-24 patchlevel 0) [i386-mingw32]
Rubygems 2.0.3
GEM_HOME C:\sbox\ruby\dump\.gems
GEM_PATH
GEM_PATHis empty, it means default value. But from where does it take the default value? See gem env.
GEM_PATH为空，表示默认值。但是它从哪里取默认值呢？见gem env。
