Bash Perl正则表达式无法正确转义

Question

我有以下命令：

grep -PoRn '(?!.+?\.trigger[\(\s]+[\'\"])([a-zA-Z\:]+)(?>![\'\"])' .

但是它抛出了这个：

-bash: ![\'\"]: event not found

为什么？ 我的正则表达式有单引号。 我在Perl上使用-P ，我已经避免了单引号和双引号，但是运气不好。

Bash版本是Ubuntu上的4.2.25(1)-release版本。

有任何想法吗？ 干杯!

Answer 1

发生这种情况是因为历史记录扩展发生在单引号内。

您可以使用$''格式解决此问题：

grep -PoRn $'(?!.+?\.trigger[\(\s]+[\'\"])([a-zA-Z\:]+)(?>![\'\"])' .

从bash手册页：

   Words of the form $'string' are treated specially.  The word expands to
   string,  with backslash-escaped characters replaced as specified by the
   ANSI C standard.  Backslash escape sequences, if present,  are  decoded
   as follows:
          \a     alert (bell)
          \b     backspace
          \e
          \E     an escape character
          \f     form feed
          \n     new line
          \r     carriage return
          \t     horizontal tab
          \v     vertical tab
          \\     backslash
          \'     single quote
          \"     double quote
          \nnn   the  eight-bit  character  whose value is the octal value
                 nnn (one to three digits)
          \xHH   the eight-bit character whose value  is  the  hexadecimal
                 value HH (one or two hex digits)
          \uHHHH the  Unicode (ISO/IEC 10646) character whose value is the
                 hexadecimal value HHHH (one to four hex digits)
          \UHHHHHHHH
                 the Unicode (ISO/IEC 10646) character whose value is  the
                 hexadecimal value HHHHHHHH (one to eight hex digits)
          \cx    a control-x character

Answer 2

! 被视为历史扩展的开始。 您可以使用以下方法暂时关闭此功能

set +H  # Turn history expansion off
grep -PoRn '(?!.+?\.trigger[\(\s]+[\'\"])([a-zA-Z\:]+)(?>![\'\"])' .
set -H  # Turn history expansion back on

您可以检查$-参数以查看是否设置了H选项，而不是无条件关闭和打开它：

[[ $- = *H* ]]; hist_on=$?   # Is history expansion enabled?
(( hist_on )) && set +H      # Turn it off if it is
grep ...
(( hist_on )) && set -H      # Turn it back on if it was

如果您能够在子Shell中运行命令，则只需关闭该子Shell的历史记录扩展即可； 当前外壳中的原始设置（打开或关闭）将保持不变。

( set +H; grep ... )