powershell - find and delete lines without string pattern in text files

Question

I'm trying to find out how to use powershell to find and delete lines without certain string pattern in a set of files. For example, I have the following text file:

111111
22x222
333333
44x444

This needs to be turned into:

22x222
44x444

given that the string pattern of 'x' is not in any of the other lines.

How can I issue such a command in powershell to process a bunch of text files?

thanks.

Answer 1

dir | foreach { $out = cat $_ | select-string x; $out | set-content $_  }

该dir命令列出当前目录下的文件；foreach遍历每个文件；cat将文件和管道读入select-string；select-string查找包含特定模式的行，在本例中为“x”；结果select-string存储在$out; 最后，用 .$out写入同一个文件set-content。

我们需要临时变量$out，因为您不能同时读取和写入同一个文件。

Answer 2

这将处理工作目录中的所有 txt 文件。检查每个文件内容，并且只允许传递其中包含“x”的行。结果被写回文件。

Get-ChildItem *.txt | ForEach-Object{
    $content = Get-Content $_.FullName | Where-Object {$_ -match 'x'}
    $content | Out-File $_.FullName
}