How to modify a text file?

Question

I\'m using Python, and would like to insert a string into a text file without deleting or copying the file. How can I do that?

Answer 1

Depends on what you want to do. To append you can open it with "a":

 with open("foo.txt", "a") as f:
     f.write("new line\n")

If you want to preprend something you have to read from the file first:

with open("foo.txt", "r+") as f:
     old = f.read() # read everything in the file
     f.seek(0) # rewind
     f.write("new line\n" + old) # write the new line before