Articles

Updated: 26 September 2025

Notes

1. https://developer.mozilla.org/en-US/docs/Web/API/Geolocation_API
2. Cloudflare:
• HTTP_CF_IPCOUNTRY
• HTTP_CF_IPCITY
• HTTP_CF_CONNECTING_IP
3. Peek the client timezone / locale

Updated: 17 September 2025

Selling Partner API

The Selling Partner API is a REST-based API that helps Amazon selling partners (i.e. sellers or vendors) programmatically access their data on orders, shipments, payments, and much more.

https://developer-docs.amazon.com/sp-api/

Amazon Business APIs

Amazon Business APIs are REST-based APIs. These APIs help Amazon Business customers programmatically access data on their orders, shipments, payments, and much more. They can also be used to create customized Amazon Business-like discovery and shopping experiences on authorized and Amazon-approved third-party sites.

1. Application Management API
2. Document API
3. Ordering API
4. Product Search API
5. Reconciliation API
6. Reporting API
7. User Management API

https://developer-docs.amazon.com/amazon-business/

Product Advertising API

Amazon’s Product Advertising API, is a web service that gives application programmers access to Amazon’s product catalog data. It enables products to be listed and/or sold through third-party websites and applications.

https://webservices.amazon.com/paapi5/documentation/

Updated: 10 January 2025

The bash script. Outputs a sorted and unique list of email addresses

#!/bin/bash

curl --silent https://lots-of-emails.example.com | \
grep -Po --file=email-regex.txt | sort | uniq

The --file option to grep reads the pattern to find from a file.

See here for an example email matching regex.

Updated: 09 September 2025

The number of options for getting started with Latex on Ubuntu is little overwhelming! This is what I did:

Install texlive at approx 250MB

sudo apt install texlive

You might also need texlive-latex-extra

sudo apt install texlive-latex-extra

Then, from this answer on StackOverflow, create file test.tex

\documentclass[a4paper,12pt]{article}
\begin{document}

The foundations of the rigorous study of \emph{analysis}
were laid in the nineteenth century, notably by the
mathematicians Cauchy and Weierstrass. Central to the
study of this subject are the formal definitions of
\emph{limits} and \emph{continuity}.

Let $D$ be a subset of $\bf R$ and let
$f \colon D \to \mathbf{R}$ be a real-valued function on
$D$. The function $f$ is said to be \emph{continuous} on
$D$ if, for all $\epsilon > 0$ and for all $x \in D$,
there exists some $\delta > 0$ (which may depend on $x$)
such that if $y \in D$ satisfies
\[ |y - x| < \delta \]
then
\[ |f(y) - f(x)| < \epsilon. \]

One may readily verify that if $f$ and $g$ are continuous
functions on $D$ then the functions $f+g$, $f-g$ and
$f.g$ are continuous. If in addition $g$ is everywhere
non-zero then $f/g$ is continuous.

\end{document}

Create a .dvi file

latex test.tex

xdvi is an open-source computer program for displaying TeX-produced .dvi files under the X Window System on Linux.

Optionally, view the output file with xdvi

xdvi test.dvi &

Produce a pdf

pdflatex test.tex

Updated: 06 July 2024

Non-identifying

Consider books and owners. A book can exist without an owner or change it’s owner. The relationship between a book and owner is non-identifying. The primary key of the parent is included in the child but not as part of the child’s primary key.

Identifying

Consider books and chapters. A chapter only exists when a book exists. The relationship between a book and its chapters is an identifying relationship. The primary key of the parent is included in the primary key of the child entity.

Updated: 08 April 2024

See https://www.atlassian.com/git/tutorials/dotfiles
See https://news.ycombinator.com/item?id=11070797

Create a bare repo in directory dfs

git init --bare $HOME/dfs/.gitdfs

Create a handy alias in your .bashrc file

gitdfs='git --git-dir=$HOME/dfs/.gitdfs --work-tree=$HOME'

Set a flag for this repo only, which hides untracked files

gitdfs config --local status.showUntrackedFiles no

Now, any file in $HOME can be versioned with normal commands

gitdfs status
gitdfs add .vimrc
gitdfs commit -m "Track my .vimrc file"
gitdfs push

Show the files tracked so far

gitdfs ls-tree -r the_branch --name-only