为什么在输入中找不到 Ruby 脚本（LoadError）？

Ruby 由 rbenv 安装。

$ ruby -v  
ruby 1.9.3p327 (2012-11-10 revision 37606) [i686-linux]

$ which ruby  
/home/user/.rbenv/shims/ruby

$ which sass  
/home/user/.rbenv/shims/sass

$ gem list
*** LOCAL GEMS ***

bigdecimal (1.1.0) 
bundler (1.2.4)
io-console (0.3)
json (1.5.4)
minitest (2.5.1)
rake (0.9.2.2)
rdoc (3.9.4)
sass (3.2.5)

这是我的 config.yml：

# Assetic Configuration
assetic:
    // ...

    ruby: /home/user/.rbenv/shims/ruby

    filters:
        cssrewrite: ~
        sass:
            bin: /home/user/.rbenv/shims/sass

        // ...

这是我得到的错误：

[message] An error occurred while running:
'/home/user/.rbenv/shims/ruby' '/home/user/.rbenv/shims/sass' '--load-path' '/path/to/symfony2/src/My/AnyBundle/Resources/public/css' '--cache-location' '/tmp' '/tmp/assetic_sassYbl6MI'

Error Output:
ruby: no Ruby script found in input (LoadError)

我的其他设置中的错误：

配置.yml：

# Assetic Configuration
assetic:
    // ...

    ruby: /home/user/.rbenv/shims/ruby

    filters:
        cssrewrite: ~
        sass: ~

        // ...

这是我得到的错误：

Error Output:
ruby: No such file or directory -- /usr/bin/sass (LoadError)

Sass 不起作用。引用 gem 是否有问题？

克隆 Rails 存储库后出现此错误：

$ rails server
c:/RailsInstaller/Ruby1.9.3/bin/ruby.exe: no Ruby script found in input (LoadError)

问题出在bin/rails and bin/rake。最上面一行是#!/usr/bin/env，但本来应该是#!/usr/bin/env ruby.