linux

• May 24, 2020. Why even own a Raspberry Pi? tags: linux, 100days

  When I first got my Raspberry Pi, I was convinced it’ll be my personal smart home device. I was thinking of all the neat projects I’d do with the hardware bits. You know, the GPIO pins and the USB ports. Not to mention the onboard wifi card, which would save me from having unsightly wires taped around my apartment.

  It’d be just like an Arduino but also Linux.

  Software is the worst

  Arduino is really easy because everything’s set up for you. You don’t need to worry about versions or support because you’re pretty sure that your Arduino supports Arduino code.

  Not so with Raspberry Pi and Linux distros. As soon as you’re worrying about a Linux machine, you have a million moving parts that all depend on each other.

  To get to the point, I spent weeks trying to figure out how to interface with the GPIO pins. There are a handful of GPIO python libraries. I think I tried a C library as well. None of them worked. I’m pretty sure it was a firmware problem, or something involving kernel extensions.

  At that point, I gave up trying.

  Having a personal Linux server is pretty great

  So instead of a smart home toy, my personal Pi is just a general-purpose Linux server. I have a Syncthing relay running on it, as well as various game servers. It’s also a music library (which plays via Bluetooth) and a general-purpose database server. At some point it was running a Discord bot and a Phoenix site. If I wanted to, I could run a Pi-hole, or seed torrents, or do whatever you people do with a general-purpose headless Linux box.

  Most importantly, it’s a nice playground for various Linux toying and misdeeds. A lot of my often-used commands.md notes were a direct result of Pi hacking.

  It’s pretty great, even if only because I don’t need to rent any more Amazon EC2 boxes (for whenever I need a 24/7 Linux box).

  Is it worth it?

  No. Yes. My expectations for the Raspberry Pi weren’t exactly met, but I’ve gotten enough use and learning out of it to justify the $35 price tag.

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  I’m writing this as part of #100DaysToOffload. You can directly check out other participating blogs or take part yourself.

  tagged: linux, 100days Why even own a Raspberry Pi? (permalink) (tweet)
  

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• modified June 25, 2020. commands.md tags: linux

  I keep around a file called commands.md which is a gigantic list of tiny how-tos. Whenever I catch myself spending forever finding the right commands to run, I add to this list.

  Here are some of those how-tos that I find myself referencing all the time. (newest first)

  Compress pngs

  for file in *.png; do pngcrush -ow "$file"; done

  Compress gifs

  gifsicle -O3 --colors 256 --batch -i *.gif

  Setting up swap

  Storing 1024 * 1M of swap in /var/swap.1

  sudo /bin/dd if=/dev/zero of=/var/swap.1 bs=1M count=1024
  sudo chmod 0600 /var/swap.1
  sudo /sbin/mkswap /var/swap.1

  Enable:

  sudo /sbin/swapon /var/swap.1

  Add to /etc/fstab to start swap on boot:

  /var/swap.1   swap    swap    defaults        0   0

  (from https://stackoverflow.com/a/17173973)

  Set a debugger breakpoint before page reload

  addEventListener('beforeunload',()=>{debugger})

  Patch pip packages from source

  e.g. for https://github.com/rkern/line_profiler:

  git clone https://github.com/rkern/line_profiler.git
  find line_profiler -name '*.pyx' -exec cython {} \;
  # do some edits
  cd line_profiler && pip install . --user 

  Installing AUR package from source (PKGBUILD file)

  make sure the base-devel group is installed

  sudo pacman -S base-devel

  then e.g. for https://aur.archlinux.org/packages/bluez-utils-compat/:

  git clone https://aur.archlinux.org/bluez-utils-compat.git
  # -s installs build deps, -r uninstalls them after build
  makepkg -sr
  # -i installs
  makepkg -i

  other flags you can add to makepkg -sr:

  -A   to ignore architecture restriction
  -c   to remove build files after a successful build

  bash script: cd to where the script is

  cd "${0%/*}"

  imagemagick change image white to transparency

  mogrify -transparent white image.png

  with fuzzy matching:

  mogrify -transparent white -fuzz 10% image.png

  install packages in octave

  e.g. to install symbolic:

  pkg -forge install symbolic
  pkg load symbolic

  add to ~/.octaverc to load on startup:

  pkg load symbolic

  tagged: linux commands.md (permalink) (tweet)