Programming

Safari on macOS offers a means of deleting saved site-specific data (cache, cookies, etc.) under Settings > Private > Manage Website Data.... Your options from there include searching for and deleting specfic content vs. vapourising everything. The latter option is the safest from a privacy and security perspective; but if you’re interested in focusing on specific cookies and other privacy leaks, you have to search one-by-one. The following script can be used to manage automate this.

While working on a project that requires querying the Anki database directly outside of the Anki desktop application, I encountered an interesting issue with sqlite3 collations. This is is just a short post about how I went about registering a collation in order to execute SQL queries against the Anki db.

The problem

Let’s try a simple query. Open the Anki database:

I use ArchiveBox extensively to save web content that might change or disappear. While a REST API is apparently coming eventually, it doesn’t appear to have been merged into the main fork. So I cobbled together a little application to archive links via a POST request. It takes advantage of the archivebox command line interface. If you are impatient, you can skip to the full source code. Otherwise I’ll describe my setup to provide some context.

So this is a little esoteric, but it meets a need I encountered; and it may meet yours if you use Espial, Keyboard Maestro and are on macOS.

For several years I’ve been using Espial a bookmark manager that looks and feels like Pinboard, but is both self-hosted and drama-free¹. Espial is easy to setup, stores its data in a comprehensible sqlite database and has an API, which comes in handy when it came to solving the problem I encountered.

Although FreeRTOS¹ is an indispensible tool for working on anything more than the simplest application on ESP32, there are some difficulties to master, such as multitasking. Multitasking using FreeRTOS is accomplished by creating tasks with xTaskCreate() or xTaskCreatePinnedToCore(). In both of these calls, one of the parameters is uxStackDepth which is the allocated stack size for the task. The FreeRTOS documentation on the subject is clear about the units for uxStackDepth:

This isn’t an exhaustive list, just a handful of date-related snippets I use in scripts.

Month name to integer

When you need to convert a month name to its integer representation (e.g. ‘April’ → 04):

#!/bin/bash

month="April"
numeric_month=$(date -j -f "%b" "$month" "+%m" 2>/dev/null)
if [ -n "$numeric_month" ]; then
    echo "$numeric_month"
else
    echo "Invalid month abbreviation"
fi

# prints "04"``

It also works with abbreviated months like “Apr”.

If you have gdate installed, then it’s easier:

Hazel is a centrepiece of my automation suite on macOS. I rely on it to watch directories and take complex actions on files contained within them. Recently I discovered an issue with files that are locked in the Finder. If files that otherwise match all the rules are locked, then Hazel will attempt to execute the rules. But the locked status may preclude execution. For example, I began seeing frequent Hazel notifications popups such as:

Obsidian is pretty reckless with file creation dates. If you modify a note in Obsidian, it updates the file creation date. This renders Dataview queries that rely on it useless. For an introduction to this issue, see this lengthy thread on the Obsidian forums.

Workarounds

There are a several solutions to this problem.

1. YAML-based dates

One can include a cdate (or similar) field in the note’s front matter and just direct the Dataview query against that, e.g. LIST FROM "" WHERE startswith(cdate,"2023-05-29") SORT file.ctime asc. This works, but of course it requires you to always place that field ahead of your note content. Some people like that; others not so much.

If you modify a file in-place using sed with the -i option, you will get a file that has a new file creation date. On macOS 13.3.1, this is absolutely 100% true, although you will read claims otherwise. I ran into this problem while implementing a Hazel rule that updates YAML automatically in my Obsidian notes.

Background

I have use YAML frontmatter in my Obsidian notes. It looks like:

---
uid:     20221120152124
aliases: [20221120152124, AllAboutShell]
cdate:   2022-11-20 15:21
mdate:   2023-05-18 05:14
type:    zettel
---

My goal is to update the mdate field whenever the file changes. Hazel is the perfect tool for this, so I set about writing a rule that covers this case. The heart of the rule is a shell script action that writes the modification date:

I use Hazel extensively for automating file management tasks on my macOS systems. Recently I found that Hazel aggressively matches an invisible system file that appears whenever you use a custom file or folder icon. I’ll describe the problem and present a workaround.

In a handful of directories, I have a rule that prevents users (me) from adding certain file types. So the rule just matches any file that is not an image, for example, and deletes it. This is all well and good until to try to add a custom icon to this directory. Since the file Icon? that gets created as a result is not an image, the Hazel rule dutifully deletes it.