Question

I have this:

(gc "$env:a.txt") -replace 'aaa', 'bbb'

I want to pipe it someway so it’ll print the lines that were changed (after the change), and only them (without simply searching for 'bbb', of course..). How ?

Edit:

I forgot to mention that I want to change the file in the process, which makes it harder (but I want to see, as a "sanity feedback", only the updated lines):

(gc "a.txt") -replace 'aaa', 'bbb' | something-here-?? | sc a.txt

Do I have to do that in two steps or there’s a way to pipe them all ?

Answer 1

For what you want, to show what is being changed and replace content of file, you can do:

gc test.txt | %{ 
    if($_ -match "this") {
        $replaced = $_ -replace "this","that"
        write-host $replaced
        $replaced
    } else{
        $_
    }

} | sc test2.txt

If you just want to see diff after replacing, you can use compare-object