Bash 正则表达式 =~ 运算符 [英] Bash regex =~ operator

问题描述

=~ 运算符叫什么?是不是只用来比较右边和左边?

为什么在运行测试时需要双方括号?

即.[[ $phrase =~ $keyword ]]

谢谢

解决方案

1. <块引用>

   =~ 运算符叫什么?

   我不确定它有没有名字.bash 文档 只是将其称为 =~ 运算符.

2. <块引用>

   是否仅用于比较右侧和左侧?

   右侧被认为是扩展的正则表达式.如果左侧匹配，则运算符返回 0，否则返回 1.

3. <块引用>

   为什么在运行测试时需要双方括号?

   因为=~是[[表达式]]复合命令的操作符.

What is the operator =~ called? Is it only used to compare the right side against the left side?

Why are double square brackets required when running a test?

ie. [[ $phrase =~ $keyword ]]

Thank you

解决方案

1. What is the operator =~ called?

   I'm not sure it has a name. The bash documentation just calls it the =~ operator.

2. Is it only used to compare the right side against the left side?

   The right side is considered an extended regular expression. If the left side matches, the operator returns 0, and 1 otherwise.

3. Why are double square brackets required when running a test?

   Because =~ is an operator of the [[ expression ]] compound command.

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