Heyo。如果在另一个帖子中回答了这个问题，我会提前道歉。我搜索了网站，但没有找到答案。但是，最接近的相关问题是Ruby on Rails / PostgreSQL - Library not Loaded error when starting server- libq.5.dylib，但它从未得到解决，答案对我没有帮助。
我正在尝试在我的Mac OSX 10.6.8上运行PostgreSQL。我已经安装了Ruby 1.9.3p392和Rails 3.2.13。
由于我的10.6.8和PostGresApp需要10.7+，我尝试使用此处提供的手动安装程序（v9.2.3）安装PG：http://www.enterprisedb.com/products-services-training/pgdownload
我首先将它安装到默认路径：/Library/PostgreSQL/9.2/。然后我安装了pg gem（PATH=$PATH:/Library/PostgreSQL/9.2/bin sudo gem install pg）。当我尝试rails s启动我的localhost时，我收到了以下错误。
经过一番阅读后，我猜测它可能是一个路径错误，所以我删除了pg gem，然后使用了postgresql卸载程序。然后我重新安装了/users/stewartmccoy/Library/PostgreSQL/9.2/...中的pg，然后重新安装了pg gem。但我仍然得到同样的错误。
关于如何正确安装PostgreSQL并让我的rails服务器运行的任何想法？
stewart-mccoys-macbook:footy_subs stewartmccoy$ rails s
/Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392/gems/pg-0.14.1/lib/pg.rb:4:in `require': dlopen(/Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392/gems/pg-0.14.1/lib/pg_ext.bundle, 9): Library not loaded: libpq.5.dylib (LoadError)
Referenced from: /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392/gems/pg-0.14.1/lib/pg_ext.bundle
Reason: image not found - /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392/gems/pg-0.14.1/lib/pg_ext.bundle
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392/gems/pg-0.14.1/lib/pg.rb:4:in `<top (required)>'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392@global/gems/bundler-1.3.4/lib/bundler/runtime.rb:72:in `require'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392@global/gems/bundler-1.3.4/lib/bundler/runtime.rb:72:in `block (2 levels) in require'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392@global/gems/bundler-1.3.4/lib/bundler/runtime.rb:70:in `each'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392@global/gems/bundler-1.3.4/lib/bundler/runtime.rb:70:in `block in require'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392@global/gems/bundler-1.3.4/lib/bundler/runtime.rb:59:in `each'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392@global/gems/bundler-1.3.4/lib/bundler/runtime.rb:59:in `require'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392@global/gems/bundler-1.3.4/lib/bundler.rb:132:in `require'
from /Users/stewartmccoy/Code/footy_subs/config/application.rb:13:in `<top (required)>'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/commands.rb:53:in `require'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/commands.rb:53:in `block in <top (required)>'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/commands.rb:50:in `tap'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/commands.rb:50:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'
stewart-mccoys-macbook:footy_subs stewartmccoy$ gem uninstall pgSuccessfully uninstalled pg-0.14.1
stewart-mccoys-macbook:footy_subs stewartmccoy$ PATH=$PATH:/users/stewartmccoy/Library/PostgreSQL/9.2/bin sudo gem install pg
Password:
Fetching: pg-0.14.1.gem (100%)
Building native extensions. This could take a while...
Successfully installed pg-0.14.1
1 gem installed
Installing ri documentation for pg-0.14.1...
Installing RDoc documentation for pg-0.14.1...
stewart-mccoys-macbook:footy_subs stewartmccoy$ rails s
/Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392/gems/pg-0.14.1/lib/pg.rb:4:in `require': dlopen(/Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392/gems/pg-0.14.1/lib/pg_ext.bundle, 9): Library not loaded: libpq.5.dylib (LoadError)
Referenced from: /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392/gems/pg-0.14.1/lib/pg_ext.bundle
Reason: image not found - /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392/gems/pg-0.14.1/lib/pg_ext.bundle
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392/gems/pg-0.14.1/lib/pg.rb:4:in `<top (required)>'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392@global/gems/bundler-1.3.4/lib/bundler/runtime.rb:72:in `require'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392@global/gems/bundler-1.3.4/lib/bundler/runtime.rb:72:in `block (2 levels) in require'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392@global/gems/bundler-1.3.4/lib/bundler/runtime.rb:70:in `each'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392@global/gems/bundler-1.3.4/lib/bundler/runtime.rb:70:in `block in require'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392@global/gems/bundler-1.3.4/lib/bundler/runtime.rb:59:in `each'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392@global/gems/bundler-1.3.4/lib/bundler/runtime.rb:59:in `require'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392@global/gems/bundler-1.3.4/lib/bundler.rb:132:in `require'
from /Users/stewartmccoy/Code/footy_subs/config/application.rb:13:in `<top (required)>'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/commands.rb:53:in `require'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/commands.rb:53:in `block in <top (required)>'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/commands.rb:50:in `tap'
from /Users/stewartmccoy/.rvm/gems/ruby-1.9.3-p392/gems/railties-3.2.13/lib/rails/commands.rb:50:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'
答案 0 :(得分：6)
错误的关键部分是：
Library not loaded: libpq.5.dylib (LoadError)
这表明ruby在运行时找不到libpq。为了解决这个问题，您应该将DYLD_LIBRARY_PATH环境变量设置为指向PostgreSQL安装的lib目录，无论是全局还是用于启动Rails的包装脚本。有关详细信息，请参阅this superuser question。
Pg gem可以在编译和安装期间找到库，因为pg_config可执行文件在PATH上，并使用它来查找libpq。它似乎不存储在运行时使用的路径，因此您必须自己设置运行时动态链接器。
简单的包装器脚本（如果您不想修改全局环境）类似于：
#!/bin/bash
export DYLD_LIBRARY_PATH=/path/to/pg/lib
exec rails "$@"
“$ @”基本上意味着“将所有参数传递给此脚本，就像它们直接传递给这里一样”。它正确地保留了引用，实质上意味着rails命令无法告诉你没有直接运行它。
答案 1 :(得分：0)
类似的stackoverflow答案建议从PATH中删除Postgres.app，卸载pg gem，然后再次安装pg gem。
（我没有花时间仔细检查这是否适用于这个问题，但它解决了我遇到的一个问题，因为我找不到它所以我想传播解决方案。）