在Merb里如果要自定义异常，需要将自定义异常继承自一个Merb自身已存的异常，比如这样
class NotExists < Merb::ControllerExceptions::NotFound ; end
并且需要在使用该异常的Controller里进行声明（放在Application里自然会是一个不错的选择），再跑一下上面报错的程序应该就可以得到正确的结果啦~ BTW:为了这个我可查了好一会资料 ：）

以下是Merb对标准Http异常的封装
class Informational < Merb::ControllerExceptions::Base; end
class Continue < Merb::ControllerExceptions::Informational; self.status = 100; end
class SwitchingProtocols < Merb::ControllerExceptions::Informational; self.status = 101; end
class Successful < Merb::ControllerExceptions::Base; end
class OK < Merb::ControllerExceptions::Successful; self.status = 200; end
class Created < Merb::ControllerExceptions::Successful; self.status = 201; end
class Accepted < Merb::ControllerExceptions::Successful; self.status = 202; end
class NonAuthoritativeInformation < Merb::ControllerExceptions::Successful; self.status = 203; end
class NoContent < Merb::ControllerExceptions::Successful; self.status = 204; end
class ResetContent < Merb::ControllerExceptions::Successful; self.status = 205; end
class PartialContent < Merb::ControllerExceptions::Successful; self.status = 206; end
class Redirection < Merb::ControllerExceptions::Base; end
class MultipleChoices < Merb::ControllerExceptions::Redirection; self.status = 300; end
class MovedPermanently < Merb::ControllerExceptions::Redirection; self.status = 301; end
class MovedTemporarily < Merb::ControllerExceptions::Redirection; self.status = 302; end
class SeeOther < Merb::ControllerExceptions::Redirection; self.status = 303; end
class NotModified < Merb::ControllerExceptions::Redirection; self.status = 304; end
class UseProxy < Merb::ControllerExceptions::Redirection; self.status = 305; end
class TemporaryRedirect < Merb::ControllerExceptions::Redirection; self.status = 307; end
class ClientError < Merb::ControllerExceptions::Base; end
class BadRequest < Merb::ControllerExceptions::ClientError; self.status = 400; end
class MultiPartParseError < Merb::ControllerExceptions::BadRequest; end
class Unauthorized < Merb::ControllerExceptions::ClientError; self.status = 401; end
class PaymentRequired < Merb::ControllerExceptions::ClientError; self.status = 402; end
class Forbidden < Merb::ControllerExceptions::ClientError; self.status = 403; end
class NotFound < Merb::ControllerExceptions::ClientError; self.status = 404; end
class ActionNotFound < Merb::ControllerExceptions::NotFound; end
class TemplateNotFound < Merb::ControllerExceptions::NotFound; end
class LayoutNotFound < Merb::ControllerExceptions::NotFound; end
class MethodNotAllowed < Merb::ControllerExceptions::ClientError; self.status = 405; end
class NotAcceptable < Merb::ControllerExceptions::ClientError; self.status = 406; end
class ProxyAuthenticationRequired < Merb::ControllerExceptions::ClientError; self.status = 407; end
class RequestTimeout < Merb::ControllerExceptions::ClientError; self.status = 408; end
class Conflict < Merb::ControllerExceptions::ClientError; self.status = 409; end
class Gone < Merb::ControllerExceptions::ClientError; self.status = 410; end
class LengthRequired < Merb::ControllerExceptions::ClientError; self.status = 411; end
class PreconditionFailed < Merb::ControllerExceptions::ClientError; self.status = 412; end
class RequestEntityTooLarge < Merb::ControllerExceptions::ClientError; self.status = 413; end
class RequestURITooLarge < Merb::ControllerExceptions::ClientError; self.status = 414; end
class UnsupportedMediaType < Merb::ControllerExceptions::ClientError; self.status = 415; end
class RequestRangeNotSatisfiable < Merb::ControllerExceptions::ClientError; self.status = 416; end
class ExpectationFailed < Merb::ControllerExceptions::ClientError; self.status = 417; end
class ServerError < Merb::ControllerExceptions::Base; end
class InternalServerError < Merb::ControllerExceptions::ServerError; self.status = 500; end
class NotImplemented < Merb::ControllerExceptions::ServerError; self.status = 501; end
class BadGateway < Merb::ControllerExceptions::ServerError; self.status = 502; end
class ServiceUnavailable < Merb::ControllerExceptions::ServerError; self.status = 503; end
class GatewayTimeout < Merb::ControllerExceptions::ServerError; self.status = 504; end
class HTTPVersionNotSupported < Merb::ControllerExceptions::ServerError; self.status = 505; end

使用Array的实现
str = "imabase64encode"
base64_str = [str].pack(”m”)
original = base64_str.unpack(”m”)

使用Base64的实现
require "base64"
enc = Base64.encode64('Send reinforcements')
plain = Base64.decode64(enc)
请注意方法pack(’m')、unpack(’m')以及encode64和decode64的用法

建议使用Array方式的实现,在Ruby1.9中将会去除Base64这个类库

see more http://en.wikipedia.org/wiki/Basic_access_authentication

Linux系统终端提示符的特征由系统环境变量PS1定义。通过命令echo $PS1查看当前设置。

PS1的值由一系列静态文本或\和转义字符序列组成，如:
PS1=”\u@\H \w$ ”

比较有用的转义序列有：
\a ASCII 响铃字符（也可以键入 \007）
\d “Wed Sep 06″ 格式的日期
\e ASCII转义字符
\h 主机名
\H 完整的主机名
\j 在此 shell 中通过按 ^Z 挂起的进程数
\l 此 shell 的终端设备名（如 “ttyp1″）
\n 换行符
\r 回车符
\s shell 的名称（如 “bash”）
\t 24小时制时间
\T 12小时制时间
\@ 带有 am/pm 的 12 小时制时间
\v bash 的版本（如 2.04）
\V Bash 版本（包括补丁级别）
\u 用户名
\w 当前工作目录（绝对路径）
\w 当前工作目录（basename）
\! 当前命令在历史缓冲区的位置
\$ 如果当前用户是super user，则插入字符#；否则插入字符$
\\ 反斜杠
\[ 出现在不移动光标的字符序列之前
\] 出现在非打印字符之后
\xxx 插入一个用三位数 xxx（用零代替未使用的数字，如 “\007″）表示的 ASCII 字符

可以通过设置PS1变量使提示符成为彩色。在PS1中设置字符序列颜色的格式为：
\[\e[F;Bm\]
其中“F”为字体颜色，编号30~37；“B”为背景色，编号40~47。
可通过“\e[0m''关闭颜色输出；特别的，当B为1时，将显示加亮加粗的文字，详细请看下面的颜色表与代码表。

颜色表

前景 背景 颜色
---------------------------------------
30 40 黑色
31 41 紅色
32 42 綠色
33 43 黃色
34 44 藍色
35 45 紫紅色
36 46 青藍色
37 47 白色

代码 意义
-------------------------
0 OFF
1 高亮显示
4 underline
5 闪烁
7 反白显示
8 不可见

如果想要设置终端提示符的样式只要把$PS1在~/.bahrc指定即可比，比如我的设置如下：
PS1="${debian_chroot:+($debian_chroot)}\u@\h\$"
export PS1
效果：
[raecoo@laptop]$

在测试过程中为Action添加了before,end过滤器,过滤器内中的日志反馈得知前置过滤器正确执行,后置过滤压根没反应,Action里的日志也一样默默无闻,郁闷,找了半天的原因,愣是没发现,后来直接上Maillist发现也有人提类似的问题.有人反馈是merb-action-args引起的问题.随即在dependencies.rb中将它注释掉,重启App发现OK了,问题确实在此.

看起来这个小玩意还不完善,我也顺手把测试环境补在了Maillist里,希望社区尽快有相关的patch出来,以下是测试环境

Ubuntu 8.10
ruby 1.8.7 (2008-08-11 patchlevel 72) [i486-linux]
merb (1.0.6.1)
merb-action-args(1.0.6.1)