how to add lines to existing file using python

Question

I already created a txt file using python with a few lines of text that will be read by a simple program. However, I am having some trouble reopening the file and writing additional lines in the file in a later part of the program. (The lines will be written from user input obtained later on.)

with open('file.txt', 'w') as file:
    file.write('input')

This is assuming that 'file.txt' has been opened before and written in. In opening this a second time however, with the code that I currently have, I have to erase everything that was written before and rewrite the new line. Is there a way to prevent this from happening (and possibly cut down on the excessive code of opening the file again)?

Answer 1

If you want to append to the file, open it with 'a' . If you want to seek through the file to find the place where you should insert the line, use 'r+' . ( docs )

Answer 2

Open the file for 'append' rather than 'write'.

with open('file.txt', 'a') as file:
    file.write('input')

Answer 3

Use 'a' , 'a' means append . Anything written to a file opened with 'a' attribute is written at the end of the file.

with open('file.txt', 'a') as file:
    file.write('input')

Answer 4

The answers above are correct, but to append the data as a new line, as opposed to tacking it onto the end of the last line in the file, use the following:

with open('file.txt', 'a') as file:
    file.writelines('input')