You may be confusing the concept of (text) file with the processes that manipulate them.
Notepad is a program, of which you can create a process. A file, on the other hand, is just a structure on your hard drive.
From a programming standpoint, Notepad doesn't edit files. It:
- reads a file into computer memory
- modifies the content of that memory
- writes that memory back into a file (which could be similarly named, or otherwise - which is known as the "Save as" operation).
Your program, just as any other program, can manipulate files, just as notepad does. In particular, you can perform exactly the same sequence as Notepad:
my_file= "myfile.txt" #the name/path of the file
with open(file, "rb") as f: #open the file for reading
content= f.read() #read the file into memory
content+= "mytext" #change the memory
with open(file, "wb") as f: #open the file for writing
f.write( content ) #write the memory into the file