如何在Bash中使用正则表达式匹配空格? [英] How can I match spaces with a regexp in Bash?

问题描述

我希望下面的代码回显是"，但事实并非如此.由于某种原因，它与单引号不匹配.为什么?

I expect the code below to echo "yes", but it does not. For some reason it won't match the single quote. Why?

str="{templateUrl: '}"
regexp="templateUrl:[\s]*'"

if [[ $str =~ $regexp ]]; then
  echo "yes"
else
  echo "no"
fi

推荐答案

替换:

regexp="templateUrl:[\s]*'"

使用:

regexp="templateUrl:[[:space:]]*'"

根据man bash，=~运算符支持man 3 regex中定义的扩展正则表达式". man 3 regex说它支持POSIX标准，并向读者推荐man 7 regex. POSIX标准支持[:space:]作为空白的字符类.

According to man bash, the =~ operator supports "extended regular expressions" as defined in man 3 regex. man 3 regex says it supports the POSIX standard and refers the reader to man 7 regex. The POSIX standard supports [:space:] as the character class for whitespace.

GNU bash手册将受支持的字符类记录为如下:

The GNU bash manual documents the supported character classes as follows:

在"["和]"中，可以使用 语法[: class :]，其中 class 是以下定义的类之一 在POSIX标准中:

Within ‘[’ and ‘]’, character classes can be specified using the syntax [:class:], where class is one of the following classes defined in the POSIX standard:

数字alpha ASCII空白cntrl数字图下部打印
点空间上位词xdigit

alnum alpha ascii blank cntrl digit graph lower print
punct space upper word xdigit

我在GNU bash文档中唯一提到的\s是在提示(例如PS1)中而不是在正则表达式中无关地使用的.

The only mention of \s that I found in the GNU bash documentation was for an unrelated use in prompts, such as PS1, not in regular expressions.

[[:space:]]将匹配一个完全相同的空格字符. [[:space:]]*将匹配零个或多个空格字符.

[[:space:]] will match exactly one white space character. [[:space:]]* will match zero or more white space characters.

POSIX正则表达式提供了两类空白:[[:space:]]和[[:blank:]] :

POSIX regular expressions offer two classes of whitespace: [[:space:]] and [[:blank:]]:

• [[:blank:]]表示空格和制表符.这使其类似于:[ \t].

• [[:blank:]] means space and tab. This makes it similar to: [ \t].

[[:space:]]，除了空格和制表符之外，还包括换行符，换行符，换页符和垂直制表符.这使其类似于:[ \t\n\r\f\v].

[[:space:]], in addition to space and tab, includes newline, linefeed, formfeed, and vertical tab. This makes it similar to: [ \t\n\r\f\v].

使用字符类的主要优点是它们对于Unicode字体是安全的.

A key advantage of using character classes is that they are safe for unicode fonts.

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