There are approximately 17 million software applications and web sites out there
built to manage your to do list. But if you're comfortable at the command line
and you don't want to depend on someone else's data format or someone else's
server, there's an age-old method that's perfect for tracking your stuff: plain
text.

Keep on top of all your tasks and projects in a simple file called todo.txt.
With a few helper scripts, you can slice, dice, sort, distribute, pipe and munge
your lists any way you please. As it should be.

See also: https://github.com/todotxt/todo.txt-cli