Let's say I have two terminals open.

In one terminal I do:

./todo
1 something
2 otherthing

In another terminal I do:

./todo -r 1

Now there is only 1 otherthing remaining.

I close the second terminal, walk away, and return.

Forgetting I had run that, with the output of the first terminal's command still in front of me, I run:

./todo -r 1

... in order to remove 1 something.

Instead of doing so, however, it removes 2 otherthing which is now known as 1 otherthing.

This is a problem because it causes a silent failure to recall the item, which is the sole and whole purpose of the program.

I would suggest either assigning a static ID when inserting, deriving the ID from the string, or using a lightweight DB like sqlite in order to manage ID assignment.