Is there a way to change multiple lines with one loop in Power Shell

Question

I have a text file like this:

info

:

I went to Paris

xxx

yyy

zzz

info

:

I went to Italy

aaa

bbb

ccc

I want this text file to be like this

Info : I went to Paris

xxx

yyy

zzz

Info : I went to Italy

aaa

bbb

ccc

So it will be like;

1- finding every colons

2- (a way) double pressing to backspace button and moving to upper line and pressing spacebar + colon + spacebar + delete button which will get those paris and italy lines to the upper line.

Answer 1

Use the regex-based -replace operator:

^{Tip of the hat to Santiago Squarzon for helping to simplify the regex and substitution.}

# Outputs to the screen; pipe to Set-Content to save back to a file as needed.
(Get-Content -Raw file.txt) -replace '(?m)(?<=^info)(?:\r?\n){2}:(?:\r?\n){2}', ' : '

For an explanation of the regex and the ability to experiment with it, see this regex101.com page.