Developing software in the Real World

Quick script to (re)create my python virtualenv

When working on rst2pdf, I use pyenv as I've written about before. Recently, I've found myself needing to recreate virtualenvs for various Python versions and then recreate them to easily reset the list of packages installed into them via pip. To my my life easier, I created a script that I can run from the command line:

This creates a new virtualenv called rst2pdf-dev-py3.9 from Python version 3.9.5, upgrade pip and install pytest, pytest-xdist… continue reading.

A few Git tips

I don't do that much that's clever with git, but I've found the following helpful. Automatically prune When you do a git fetch or git pull, you can ask it to remove remote tracking branches for a branch that has been removed on the remote by using the –prune flag. This can be automated globally with:

and if you only want it for a specific repository, you can use:

One line log I… continue reading.

Using MailHog via Docker for testing email

I recently needed to modify the emails that a client project sends out. It was set up to send via SMTP and so the easiest way to do this for me was to add a local MailHog instance and point the application at it. Manually running via Docker The quickest and easiest way to do this is via Docker. Manually, we can do:

This will run MailHog with the SMTP port exposed on localhost… continue reading.

Recursive PHP lint

There are many scripts that recursively execute php -l on a set of files or directories. This is mine:

I store it in ~/bin and usually run it like this:

There are a few interesting bash tricks that I picked up when I wrote this. Firstly, you need to set IFS to break on new line rather than space otherwise the find command doesn't work with spaces in file names. I also discovered… continue reading.

Prevent an external drive from auto mounting on macOS

I have an external drive attached to the USB hub on my Thunderbolt Display that I use to clone my laptop's internal drive every night using the schedule feature of SuperDuper!. At the appointed time, SuperDuper! will mount the external drive, clone the internal drive and then unmount the external drive again which is very convenient. However, whenever I plug in my laptop, the drive automatically mounts. This doesn't particularly worry me, but when I… continue reading.

Ignoring mass reformatting commits with git blame

I've recently merged a PR by Stephen to rst2df that reformats the entire codebase to align with PEP 8. As rst2pdf is over a decade old, this has resulted in a lot of changes to the files which now have Stephen's name attached. This affects git blame. For example:

Stephen is now implicated as having changed this for loop, but all he did was run the tool that reformatted it. –ignore-rev to the rescue!… continue reading.

Turn off foreign key checks when restoring a mysql file dump

I recently received a MySQL dump file where the various tables in it had foreign keys to each other. I usually restore with this command: mysql –login-path=rob < dump.sql but this generated the error: ERROR 1217 (23000) at line 288805: Cannot delete or update a parent row: a foreign key constraint fails It turns out that the easiest way to solve this is to use the –init-command switch to set foreign keys off for this… continue reading.

Extracting the base name of a file in Bash

I have a handy bash script that transcodes videos using Don Meton's video_transcoding tools. This script was written in a hurry and one limitation it had was that it re-transcoded any source file even if the output file already existed. The script looked like this:

What it should do is only run transcode.sh if the output file doesn't exist, so I updated it. Parameter expansion to the rescue! I needed to extract the base… continue reading.

Using Docker to create a MySQL server

When working on test code on my computer, I usually use the built-in PHP server (php -S) which works nicely. Every so often, I need access to MySQL and I use Docker to temporarily create a MySQL server for me. This is how I do it. The magic command is:

This creates a Docker container called "mysql" on port 3306. We pass three environment variables: MYSQL_USER, MYSQL_PASSWORD & MYSQL_DATABASE which are our credentials and… continue reading.

Getting started writing an Alexa Skill

We now have 4 Amazon Echo devices in the house, and, inspired by a demo LornaJane gave me at DPC, I have decided to write some skills for it. This article covers what I learnt in order to get my first Swift skill working. Our bins are collected by the council every other week; one week it's the green recycling bin and the other week, it's the black waste bin. Rather than looking it up,… continue reading.