TIL

This is a running list of things that I’ve learned. Sometimes they are particular technical facts. I’m a neophyte in a lot of areas; so of these things will seem quite mundane. Sometimes they are more conceptual. Maybe someone will find them useful. Maybe that someone is my future self.

Wednesday, February 17, 2021

A couple of terms that deal with perceptual distortions and cognitive bias:

  • apophenia - a tendency to see connections between two unrelated things.
  • pareidolia - the faulty perception of a pattern in an image, e.g. seeing a face in a geologic formation on Mars.

Pareidolia is a specific form of apophenia.

Friday, January 29, 2021

Custom aliases in oh-my-zsh

With oh-my-zsh, you can store custom aliases in multiple (?per application) file under .oh-my-zsh/custom giving them .zsh file extensions.1

¶For example, in my hugo.zsh file, I have:

alias hnewtil="/Users/alan/Documents/blog/ojisan/scripts/newtil.sh"
alias gtojisan="cd /Users/alan/Documents/blog/ojisan; ls -l;"

Executing inline Python in a shell script

It’s possible using the -c command.2

python -c 'import foo; foo.bar()'

  1. https://scottwhittaker.net/posts/oh-my-zsh-custom-aliases/ ↩︎

  2. https://stackoverflow.com/questions/16908236/how-to-execute-python-inline-from-a-bash-shell ↩︎

Thursday, January 28, 2021

A bunch of Unix date scripting things

Unix shell scripting is not one of my better-know areas of programming, but it’s on my list of things to learn. Some interesting bits about the date function.1

  1. Want the long date, like Thursday, January 28, 2021? → date +"%A, %B %d, %Y"
  2. Want something like the above but with abbreviated month Thursday, Jan 28, 2021? → date +"%A, %b %d, %Y"
  3. Time zone in the format of "-05:00” on macOS is:
#!/bin/bash

tz=$(date +"%z" | sd '(\d{2})(\d{2})' '$1:$2')
echo $tz
  1. Long date in the format of 2021-01-28T05:30:48-05:00 that is use by Hugo2:
tz=$(date +"%z" | sd '(\d{2})(\d{2})' '$1:$2')
md_date=`date +"%Y-%m-%dT%H:%M:%S"`
  1. Speaking of dates, this reference has very detailed information on date and time in the Unix shell.
  2. Date in the format of 2021-01-28 is date +"%Y-%m-%d"

Unix slurp command output into a variable

In the UNIX shell, slurping the output of the command into a variable is done this way:3

OUTPUT=$(ls -1)
echo "${OUTPUT}"

MULTILINE=$(ls \
   -1)
echo "${MULTILINE}"

Append or overwrite a file in Unix shell

You can either append to a file or overwrite the contents from the shell.4

To append to a file, it’s echo "hello" >> file.txt whereas to overwrite the contents of a file, it’s echo "hello" > file.txt

Function Symbol
Append >>
Overwrite >

  1. This all pertains to the macOS flavour of the Unix shell. There are important differences, seemingly in the date function, for example. ↩︎

  2. I should know what that format is called, but I don’t. I think it’s ISO 8601. Also, this requires sd. If you don’t have it, you’d need sed instead. ↩︎

  3. Source - Stack Overflow ↩︎

  4. Source - Stack Overflow ↩︎

Wednesday, January 27, 2021

W3schools.com has a CSS library that’s quite nice. I often use Bootstrap; but I like some of the visual features here better. For example, I like their tags because they have more flexible use of colour.


If you want to fetch from a Python dictionary, but you need a default value, this is how you do it:

upos_badge = {'noun': 'lime','verb': 'amber', 'adv': 'blue',}
badge_class_postfix = upos_badge.get(value.lower(), 'light-grey')

I recently learned about DeepL as an alternative to Google Translate. It seems really good.