title: batch file - find string in files with substring of filename and replace it
body: <p>I would like to ask you, how can I do this:
  I have three files in folder, <code>car.txt</code>, <code>bus.txt</code>, <code>plane.txt</code>. File <code>car.txt</code> contains some text with string for example <code>test="in_car</code>" and I know, that I find word with prefix "<code>in_</code>" + word from filename "<code>car</code>" and if I find it, I want to replace it by word "<code>hello</code>". And for files <code>bus.txt</code> and <code>plane.txt</code> do same thing, find word <code>in_bus</code> and replace it by <code>hello</code> etc. And I know that prefix "<code>in_</code>" is only at this place.
  Please, can you help me?</p>
  
  <p>I try something like this: </p>
  
  <pre><code>for /R "../myFolder" %%f in (*.txt) do ( 
      set FILENAME=%%~nf
      set PREFIX=in_
      set REPLACETEXT=hello
      SET string=%%A
      set modified=!string:%PREFIX%%FILENAME%=%REPLACETEXT%!
  ) 
  </code></pre>
  
  <p>but it is not working and I don't know, how can I save it to current file (replace it in file)</p>