Text substitution (reading from file and saving to the same file) on linux with sed

I want to read the file "teste", make some "find&replace" and overwrite "teste" with the results. The closer i got till now is:

$cat teste
I have to find something
This is hard to find...
Find it wright now!

$sed -n 's/find/replace/w teste1' teste

$cat teste1
I have to replace something
This is hard to replace...

If I try to save to the same file like this:

$sed -n 's/find/replace/w teste' teste

or:

$sed -n 's/find/replace/' teste > teste

The result will be a blank file...

I know I am missing something very stupid but any help will be welcome.

UPDATE: Based on the tips given by the folks and this link: https://learnbyexample.github.io/learn_gnused/in-place-file-editing.html here's my updated code:

sed -i -e 's/find/replace/g' teste

Solution

On Linux, sed -i is the way to go. sed isn't actually designed for in-place editing, though; historically, it's a filter, a program which edits a stream of data in a pipeline, and for this usage you would need to write to a temporary file and then rename it.

The reason you get an empty file is that the shell opens (and truncates) the file before running the command.