I don't use a single text file, but I do keep notes with text files. I created a little bash script to help me do that.

I type 'note' in the terminal and it opens up a new file at ~/notes/$year/$month/$day/note.md in vim in insert mode with a timestamp already inserted for me.

https://github.com/dcchambers/note-keeper

I do kind of like the idea of having a single file for searchability, but I do already have powerful search of my `notes` directory with grep.