Python: Open a file, search then append, if not exist

Question

I am trying to append a string to a file, if the string doesn\'t exit in the file. However, opening a file with a+ option doesn\'t allow me to do at once, because o

Answer 1

You can set the current position of the file object using file.seek(). To jump to the beginning of a file, use

f.seek(0, os.SEEK_SET)

To jump to a file's end, use

f.seek(0, os.SEEK_END)

In your case, to check if a file contains something, and then maybe append append to the file, I'd do something like this:

import os

with open("file.txt", "r+") as f:
    line_found = any("foo" in line for line in f)
    if not line_found:
        f.seek(0, os.SEEK_END)
        f.write("yay, a new line!\n")