On Linux, download and install the diary from the Open Build Service:

📦 stable
🌜 nightly

On MacOS, install with Homebrew: brew install diary

Check the README for further build options.

Set the EDITOR environment variable to your favourite text editor:

export EDITOR=vim

Run the diary, with the folder for the text files as first argument:

diary ~/.diary

Or, set the environment variable DIARY_DIR to the desired directory. The text files in this folder will be named 'yyyy-mm-dd'.