我继承了Ruby on Rails项目。它是全部压缩的，所以作为第一步，我想让它在我的桌面Mac上运行：
脚本/服务器
=＆GT;启动WEBrick ...
/Library/Ruby/Gems/1.8/gems/activerecord-2.2.2/lib/active_record/connection_adapters/abstract/connection_specification.rb:74:in establish_connection': Please install the postgresql adapter: gem install activerecord-postgresql-adapter`（没有这样的文件到load - pg）（RuntimeError）
所以，我尝试安装activerecord-postgresql-adapter gem然后得到这个：
$ sudo gem install activerecord-postgresql-adapter
Password:
Building native extensions. This could take a while...
ERROR: Error installing activerecord-postgresql-adapter:
ERROR: Failed to build gem native extension.
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby extconf.rb mkmf.rb在/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/ruby.h找不到ruby的头文件
Gem文件将保留在/Library/Ruby/Gems/1.8/gems/pg-0.14.1中以供检查。 结果记录到/Library/Ruby/Gems/1.8/gems/pg-0.14.1/ext/gem_make.out
如何安装此必需的gem？
由于