HPR4251: Dave and MrX turn over a new leaf

Hacker Public Radio

This show has been flagged as Explicit by the host.

Introduction

Hosts:

• MrX
• Dave Morriss

We recorded this on Saturday September 14^th 2024. This time we were at Swanston Farm, a place we had previously visited for lunch in March 2024.

After lunch we adjourned to Dave's car (Studio N) in the car park, and recorded a chat. The details of why it is Studio N instead of Studio C is mentioned in the chat itself!

Preparing this show has taken longer than usual this time - apologies!

Topics discussed

• Studio change:
  • Sadly, since the last recording Studio C (Dave's 10-year old Citroën C4 Picasso) self-destructed. It was a diesel car and one of the fuel injectors failed and destroyed the engine management system as it died. It wasn't worth repairing!
  • The replacement is Studio N, a Nissan Leaf, which is an EV (electric vehicle). The price of nearly new EV cars is fairly good in the UK at this time in 2024, so it seemed like a good opportunity to get one.
  • Learning to own and drive an EV can be challenging to some extent:
    • "Range anxiety" and access to charging stations
    • Regenerative braking
    • Fast (DC) charging on the road is relatively expensive (£0.79p per kWh), but is convenient
    • Ideally, a home (AC) charger is required. It will be slower (7 kW per hour) but will be cheaper with a night tariff (£0.085 per kWh versus £0.25 per kWh normal rate)
    • There is potential, with solar panels and a battery, to use free electricity to charge an EV at home
  • MrX might like to move to an EV in the future

• YouTube channels:
  • Dave is subscribed to a channel called "The Post Apocalyptic Inventor (TPAI)" and recently shared one of the latest videos with MrX. The channel owner collects discarded items from scrapyards in Germany, or buys old bits of equipment, and gets them working again.
    • Milling Machine Adventure! Bring her Home! / Gantry Build
    • I built a CNC Plasma Cutting Table from Scrap!

• Databases:
  • MrX used dBase on DOS in the past, and received some training in databases.
  • In 2017 he obtained a large csv (comma-separated values) file from the OFCOM (Office of Communications, UK) website containing their Wireless Legacy Register, which contains licensees and frequencies with longitude and latitude values. A means of interrogating this file was sought, having found that spreadsheets were not really very good at handling files of this size (around 200,000 records).
  • MrX used the xsv tool, which was covered in shows hpr2698 and hpr2752 by Mr. Young. It allows a CSV file to be interrogated in quite a lot of detail from the command line. However, with a file of this size it was still quite slow.
  • In a discussion with Dave the subject of the SQLite database came up. Using the SQLite Browser it was simple to load this CSV file into a database and gain rapid access to its contents. SQLite databases may also be queried through a command-line interface which can also be run on a Raspberry Pi, phones, tablets and on a ChromeBook.

• The textimg tool:
  • This is a command to convert from colored text (ANSI or 256) to an image. Dave generates coloured text from his meal database (HPR show hpr3386 :: What's for dinner?, this being a later enhancement), then captures the output and sends it to a Telegram channel shared with his family.
  • Dave also exchanges weather data obtained from the site wttr.in with Archer72 on Matrix.
  • This is a useful tool for generating images from text, including any text colours. It can be installed from the GitHub copy, and maybe from some package repositories.

• Using coloured text in BASH (Dave responding to MrX):
  • I have used a function to define variables with colour names:
    • Call a function define_colours which defines (and exports) variables called red, green, etc.
    • Using red=$(tput setaf 1); export red
  • I use the colours in two ways:
    • Method 1: use these names in echo "${red}Red text${reset}"
    • Method 2: use another function coloured which takes two arguments, a colour name (as a string) and a message. The script encloses the message argument in a colour variable and a reset. The colour name argument is used in a redirection to turn red into the contents of the variable $red.
  • This probably needs a show to explain things fully.

• Terminal multiplexers:
  • Dave and MrX use GNU screen.
  • Both recognise that the alternative tmux might be better to use in terms of features, but are reluctant to learn a new interface!
  • Dave has noticed a new open-source alternative called zellij but has not yet used it.

• Variable weather:
  • Dealing with hot weather: YouTube, Techmoan channel PERSONAL AIRCON - Ranvoo Aice Lite Review
  • MrX had recently had a holiday in the Lake District where the weather was good.
  • In Scotland the weather has been wet and windy in the same period.

• Spectrum24, OggCamp:
  • MrX is attending his first OggCamp in Manchester. Dave will be attending too, as will Ken.
    • HPR has a table/booth at OggCamp.
  • Ken was recently at Spectrum24, an amateur radio conference in Paris.
    • Meshtastic an open source, off-grid, decentralized, mesh network built to run on affordable, low-power devices

• Old inkjet printers:
  • MrX has an Epson R300 printer where the black ink seems to have dried up.
  • Dave has an old HP Inkjet with the same type of problem. This printer has a scanner and FAX capability. An HPR show was done in 2015 describing how it was set up to use a Raspberry Pi to make it available on the local network.

• Propelling or mechanical pencils:
  • Dave had a Pentel GraphGear 1000 propelling (aka mechanical) pencil which was mentioned on HPR show 3197. This was dropped onto concrete, and didn't appear damaged at the time, but it apparently received internal damage and eventually fell apart.

Links

• Electric cars:
  • EV (electric vehicle)
  • Regenerative braking

• Databases
  • SQLite:
    • SQLite
    • SQLite Browser
    • An Easy Way to Master SQLite Fast
    • Open source SQLite Studio available for Linux SQLiteStudio
  • SQL:
    • Origins: The Birth of SQL & the Relational Database
    • Intricacies: MySQL JOIN Types Poster (Steve Stedman)
  • Design:
    • How to Fake a Database Design - Curtis Poe (Ovid)

• The textimg tool:
  • GitHub repository: textimg

• zellij:
  • Website: zellij
  • Github repository: zellij
  • Quote from the repo: Zellij is a workspace aimed at developers, ops-oriented people and anyone who loves the terminal. Similar programs are sometimes called "Terminal Multiplexers".

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