多行正则表达式匹配配置块 [英] Multiline regex to match config block

问题描述

我在尝试从文件中匹配某个配置块(多个)时遇到了一些问题.下面是我试图从配置文件中提取的块:

I am having some issues trying to match a certain config block (multiple ones) from a file. Below is the block that I'm trying to extract from the config file:

ap71xx 00-01-23-45-67-89
 use profile PROFILE
 use rf-domain DOMAIN
 hostname ACCESSPOINT
 area inside
!

有多个这样的，每个都有不同的 MAC 地址.如何跨多行匹配配置块?

There are multiple ones just like this, each with a different MAC address. How do I match a config block across multiple lines?

推荐答案

您可能遇到的第一个问题是，为了跨多行匹配，您需要将文件内容作为单个字符串处理，而不是逐行处理.例如，如果您使用 Get-Content 读取文件的内容，那么默认情况下它会为您提供一个字符串数组 - 每行一个元素.要跨行匹配您希望文件在单个字符串中(并希望文件不要太大).你可以这样做:

The first problem you may run into is that in order to match across multiple lines, you need to process the file's contents as a single string rather than by individual line. For example, if you use Get-Content to read the contents of the file then by default it will give you an array of strings - one element for each line. To match across lines you want the file in a single string (and hope the file isn't too huge). You can do this like so:

$fileContent = [io.file]::ReadAllText("C:\file.txt")

或者在 PowerShell 3.0 中，您可以使用带有 -Raw 参数的 Get-Content:

Or in PowerShell 3.0 you can use Get-Content with the -Raw parameter:

$fileContent = Get-Content c:\file.txt -Raw

然后你需要指定一个正则表达式选项来匹配跨行终止符，即

Then you need to specify a regex option to match across line terminators i.e.

• SingleLine 模式(. 匹配任何字符包括换行符)，以及
• 多行模式(^ 和 $ 匹配嵌入的行终止符)，例如
• (?smi) - 注意i"是忽略大小写

• SingleLine mode (. matches any char including line feed), as well as
• Multiline mode (^ and $ match embedded line terminators), e.g.
• (?smi) - note the "i" is to ignore case

例如:

C:\> $fileContent | Select-String '(?smi)([0-9a-f]{2}(-|\s*$)){6}.*?!' -AllMatches |
        Foreach {$_.Matches} | Foreach {$_.Value}

00-01-23-45-67-89
 use profile PROFILE
 use rf-domain DOMAIN
 hostname ACCESSPOINT
 area inside
!
00-01-23-45-67-89
 use profile PROFILE
 use rf-domain DOMAIN
 hostname ACCESSPOINT
 area inside
!

使用 Select-String cmdlet 进行搜索，因为您可以指定 -AllMatches 它将输出所有匹配项，而 -match运算符在第一次匹配后停止.有道理，因为它是一个布尔运算符，只需要确定是否存在 a 匹配.

Use the Select-String cmdlet to do the search because you can specify -AllMatches and it will output all matches whereas the -match operator stops after the first match. Makes sense because it is a Boolean operator that just needs to determine if there is a match.

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