正则表达式整理符号 [英] Regex collating symbols

问题描述

我试图了解校对符号"匹配是如何工作的，但我并没有得出结论.我知道这意味着匹配一个确切的序列，而不仅仅是匹配字符，即:

I tried to understand how 'collating symbols' match works but I did not come out this. I understood that it means matching an exact sequence instead of just the character(s), that is:

echo "ciiiao" | grep '[oa]'     --> output 'ciiiao'
echo "ciiiao" | grep '[[.oa.]]' --> no output
echo "ciiiao" | grep '[[.ia.]]' --> output 'ciiiao'

但是，第三个命令不起作用.我错了还是我误解了什么?

However, the third command does not work. Am I wrong or I misinterpret something?

我已阅读此正则表达式教程.

I have read this regexp tutorial.

推荐答案

POSIX正则表达式规范的元素，并且并不广泛支持.

Collating symbols are typically used when a digraph is treated like a single character in a language. They are an element of the POSIX regular expression specification, and are not widely supported.

例如，在某些语言中，"sh"被视为单个字符.假定语言环境文件已定义它(只有在当前语言环境中定义了校对符号，该符号才会起作用)，则将归类符号 [[.sh.]] 视为单个字符.同样，搜索.或 [^ a] 也可以匹配"sh".如果语言环境在字母中的"h"之后定义了"sh"，则 [g-i] 也将匹配"sh".

For example, in some languages "sh" is treated as a single character. Assuming the locale file defines it (a collating symbol will only work if it is defined in the current locale), the collating symbol [[.sh.]] is treated like a single character. Likewise, searching for . or [^a] could also match "sh." If the locale defined "sh" as following "h" in the alphabet, then [g-i] would also match "sh."

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