Can you move the cursor while appending a file?

Question

I know how to use seek() to move where Python will read a file. Is there any way to do this when in append mode when editing a file? (I have tried using r+ and a+ for read and write, but r+ overwrites the character in the specified position and a+ still seems to insert text at the end of the file)

file1.py:

filetwo = open("file2.txt", "a")
filetwo.seek(13)
filetwo.write("5")
filetwo.close()

file2.txt:

1, 2, 3, 4, 6, 7, 8, 9, 10

@JeffUK No, I have edited my question to explain why it doesn't work for me. Thanks! — Elliot Harrell, Feb 20 '22 at 20:49
Open the file as `a+` https://stackoverflow.com/questions/1466000/difference-between-modes-a-a-w-w-and-r-in-built-in-open-function — ti7, Feb 20 '22 at 20:50
The concept of files does not have something like an "insert". — Thomas Weller, Feb 20 '22 at 20:51
@ti7 I tried this but it seems to still insert the text at the end of the file. — Elliot Harrell, Feb 20 '22 at 20:52

score 2 · Accepted Answer · answered Feb 20 '22 at 20:54

The concept of files does not have something like an "insert" in any file system I know (but one could probably design such a file system). To achieve an insert you have to

read the existing file up to the point where you want to insert
write that content into a new file
write the content that you want to insert into the new file
read the rest from the existing file
write that rest into the new file
delete the existing file
rename the new file to the same name as the old file

Can you move the cursor while appending a file?

1 Answers1