Search for paragraphs without specific patterns

[vbd]

Input

row 1
row 2

row 1

row 1
row 2
row 3
row 4
row 5
row 6

row 1
row 2
row 3
row 4
row 5

How is it possible to search for a paragraph consisting only of 1 line, without a specific pattern of charachters?
Should return only

row 1

And if it is possible how would I do so for a paragraph consisting excatly of 5 lines?
Should return

row 1
row 2
row 3
row 4
row 5

I mix both cases here because I think the regex, if possible, will look very differently.

Thanks in advance.

Update:
I tried something like: https://regex101.com/r/VXKAAN/1 but I'm really not good at regex.

[BurntSushi]

ripgrep is a line oriented tool. So it's generally not the right tool for this sort of task. By "line oriented tool," what I mean is that its basic mode of operation is to iterate over lines in a file and print only the ones that match. What you want to do requires something more powerful: the ability to reason about lines more holistically than that. ripgrep does not give you that arbitrary power.

With that said, ripgrep does have a -U/--multiline flag that will let you employ such reasoning in a limited way. To achieve what you want, for 1 and 5 lines, respectively:

$ rg -U '(?-m)(^|\n\n)(?P<paragraph>.+($|\n)){1}($|\n)' -o
input
4:row 1

$ rg -U '(?-m)(^|\n\n)(?P<paragraph>.+($|\n)){5}($|\n)' -o
input
13:row 1
14:row 2
15:row 3
16:row 4
17:row 5

EDIT: Obviously, this only works if you're using \n as line endings. But if you're on Windows, it's likely that your lines end with \r\n instead of just \n. So you'll need to replace \n with \r\n in the regex above. And possibly use the --crlf flag.

[vbd]

At first thank you very much for your help.

I tested it my windows pc but It didn't work. I tried it in CMD and Powershell. Did replace the ' with " for first debugging.
In powershell:
rg -U '(?-m)(^|\n\n)(?P<paragraph>.+($|\n)){1}($|\n)' -o input
returns no error, no result

In CMD:
rg -U '(?-m)(^|\n\n)(?P<paragraph>.+($|\n)){1}($|\n)' -o input
returns "file can't be found" (in german: Das System kann die angegebene Datei nicht finden.)

rg -U "(?-m)(^|\n\n)(?P<paragraph>.+($|\n)){1}($|\n)" -o input
returns no error, no result

Any idea what I am missing?

[BurntSushi]

Well, you need to make sure input is a real file... Otherwise, I don't know, I don't use Windows. Sorry. It works for me.

[vbd]

input is a real file.
Just tested it on cygwin bash, also did not work.

File is named input, to be able to upload I named it input.txt.

input.txt

Thanks for your help anyway.

[BurntSushi]

Sigh. Windows uses \r\n for line endings. Not \n. So you need '(?-m)(^|\r\n\r\n)(?P<paragraph>.+($|\r\n)){5}($|\r\n)'. And maybe the --crlf flag to handle some edge cases.

[vbd]

I am so stupid, I have overlooked it once again ... I created a file for testing purposes on my windows box. The source files are from a linux machine.
Thank you so so so much. It works like a charm.