Source: bsdmainutils
    Maintainer: Debian Bsdmainutils Team 
    [...]
    Description-en: display a calendar and the date of Easter
    [...] This utility displays a
    simple calendar in a traditional or an alternative and more advanced layout,
    and the date of Easter.

https://github.com/viviparous/showcal

https://turnturnturn.me/

> someone should rewrite it in a decent language

was coded in BAGS (bash, awk, grep, sed) and Postscript circa 1987 [1], and it's still working almost 40 years later in 2026 !

Perhaps it was in fact coded decently. And licensed decently as well. ^_^

[1]

    AUTHOR:
        Patrick Wood
        Copyright (C) 1987 by Pipeline Associates, Inc.
        Permission is granted to modify and distribute this free of charge.

Quite interesting how people are so different.

For a long time, I just had some "future log" pages (actually I tend to have 3-4 years worth) at the start of each book, where I have 3 months per page so I can drop in important future events (like booking a holiday 12 months out), birthdays etc (although I only copy these forward annually) and then a "month ahead" page at the start of each page where I had a line per day. I found that I wasn't really using most of these lines though because mostly only the weekends were useful for me.

I switched to having a 9 month-view where I have a line per week, and the left page is the weekend and the right page for weekdays. I pen in the dates for every weekend day, and tend to only fill in the dates on the weekdays when I have something to add on a specific day. I only ever write in pencil on these pages apart from the dates in pen, so blocks can be erased easily, and I tend to use corner square brackets to highlight start and ends of longer special periods like holidays. It's a bit annoying not having a full 12-month view, but I also like the fact that because it starts at some key event, then it usually crosses the year boundary. I tend to use these as future planning rather than recording events, and if it gets messy with too much rubbing out or crossing out, then I'll just start a new one from current (or occasionally a couple of weeks back) and put a note on the old page linking to the page number with the new calendar, and a note on the new one linking to the last.