如何在 bash 脚本中使用正则表达式? [英] How do I use regular expressions in bash scripts?

问题描述

我想使用正则表达式检查变量是否具有有效年份.阅读 bash 手册 我知道我可以使用运算符=~

I want to check if a variable has a valid year using a regular expression. Reading the bash manual I understand I could use the operator =~

查看下面的示例，我希望看到不正常"，但我看到的是正常".我做错了什么?

Looking at the example below, I would expect to see "not OK" but I see "OK". What am I doing wrong?

i="test"
if [ $i=~"200[78]" ]
then
  echo "OK"
else
  echo "not OK"
fi

推荐答案

在 3.1 和 3.2 之间发生了变化:

It was changed between 3.1 and 3.2:

这是对自 bash-3.1 发布以来添加到 bash-3.2 的新特性的简要描述.

This is a terse description of the new features added to bash-3.2 since the release of bash-3.1.

引用 [[ 命令的 =~ 运算符的字符串参数现在会强制字符串匹配，就像其他模式匹配运算符一样.

Quoting the string argument to the [[ command's =~ operator now forces string matching, as with the other pattern-matching operators.

所以使用它而不使用引号:

So use it without the quotes thus:

i="test"
if [[ $i =~ 200[78] ]] ; then
    echo "OK"
else
    echo "not OK"
fi

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