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运行：OSX 10.9.4，Ruby 2.1.5，Rails 4.1.8（但项目子文件夹中为4.1.6）错误：无法在OSX上创建gem本机扩展（捆绑安装）10.9.4
我在项目子文件夹中安装gem存在问题。捆绑安装似乎失败在jquery-rails 3.1.2。在Stackoverflow找不到解决方案，所以询问是否有人知道如何解决？
下面是输出：
Macintosh:~ asanchez$ cd Projects
Macintosh:Projects asanchez$ ls
rails-2
Macintosh:Projects asanchez$ cd rails-2
Macintosh:rails-2 asanchez$ bundle install
Fetching gem metadata from https://rubygems.org/.........
Installing rake 10.3.2
Using i18n 0.6.11
Using json 1.8.1
Using minitest 5.4.3
Using thread_safe 0.3.4
Using tzinfo 1.2.2
Installing activesupport 4.1.6
Using builder 3.2.2
Using erubis 2.7.0
Installing actionview 4.1.6
Using rack 1.5.2
Using rack-test 0.6.2
Installing actionpack 4.1.6
Using mime-types 2.4.3
Using mail 2.6.3
Installing actionmailer 4.1.6
Installing activemodel 4.1.6
Using arel 5.0.1.20140414130214
Installing activerecord 4.1.6
Installing sass 3.2.19
Installing bootstrap-sass 3.3.1.0
Installing coffee-script-source 1.8.0
Installing execjs 2.2.2
Installing coffee-script 2.3.0
Using thor 0.19.1
Installing railties 4.1.6
Installing coffee-rails 4.0.1
Installing font-awesome-sass 4.2.2
Using hike 1.2.3
Using multi_json 1.10.1
Installing jbuilder 2.2.5
Installing jquery-rails 3.1.2
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
/Users/asanchez/.rvm/rubies/ruby-2.1.5/bin/ruby -r ./siteconf20141202-33892-1jyqcz2.rb extconf.rb
checking for pg_config... no
No pg_config... trying anyway. If building fails, please try again with
--with-pg-config=/path/to/pg_config
checking for libpq-fe.h... no
Can't find the 'libpq-fe.h header
*** 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:
\t --with-opt-dir
\t --with-opt-include
\t --without-opt-include=${opt-dir}/include
\t --with-opt-lib
\t --without-opt-lib=${opt-dir}/lib
\t --with-make-prog
\t --without-make-prog
\t --srcdir=.
\t --curdir
\t --ruby=/Users/asanchez/.rvm/rubies/ruby-2.1.5/bin/ruby
\t --with-pg
\t --without-pg
\t --with-pg-config
\t --without-pg-config
\t --with-pg_config
\t --without-pg_config
\t --with-pg-dir
\t --without-pg-dir
\t --with-pg-include
\t --without-pg-include=${pg-dir}/include
\t --with-pg-lib
\t --without-pg-lib=${pg-dir}/lib
extconf failed, exit code 1
Gem files will remain installed in /Users/asanchez/.rvm/gems/ruby-2.1.5/gems/pg-0.17.1 for inspection.
Results logged to /Users/asanchez/.rvm/gems/ruby-2.1.5/extensions/x86_64-darwin-13/2.1.0/pg-0.17.1/gem_make.out
An error occurred while installing pg (0.17.1), and Bundler cannot continue.
Make sure that `gem install pg -v '0.17.1'` succeeds before bundling.而且，这里的输出，当我检查的Rails版本：
Macintosh:rails-2 asanchez$ rails --version
Rails 4.1.6
Macintosh:rails-2 asanchez$ cd ..
Macintosh:Projects asanchez$ rails --version
Rails 4.1.8