Nick Taylor

Posted on Oct 22, 2021

October 22nd, 2021: What did you learn this week?

#weeklylearn #discuss #weeklyretro

It's that time of the week again. So wonderful devs, what did you learn this week? It could be programming tips, career advice etc.

![Information flowing through your brain](https://media.giphy.com/media/qKltgF7Aw515K/giphy.gif)

Feel free to comment with what you learnt and/or reference your TIL post to give it some more exposure.

#todayilearned

Summarize a concept that is new to you.

Top comments (29)

Heiker • Oct 22 '21 • Edited

I used xargs this week.

It looks like the open command can't take data from the standard input, so I ended up using something like this.

some_command | xargs -r -I{} open {}

For those who don't know, xargs (with the right arguments) can act like the map method on javascript arrays. So you can imagine the above doing something like this:

some_command().map(arg => open(arg))

grendel • Oct 23 '21

xargs can come in handy in a pinch, but it's usually unnecessary and the way it generates arguments can cause some complications. I can't think of a case where xargs would be more appropriate than Command Substitution or a while read loop, e.g.:

open "$(some_commands)" #thus you fully control word-splitting

some_commands | \
  while IFS= read -r line; do #unsetting IFS here prevents word-splitting
    some_other_commands "$line"
    even_some_more_commands "$line"
    #vars declared in here are not valid afterwards,
    #since they are declared inside the pipeline subshell
    #and its environment does not hoist
    #This includes $line
  done

#alternatively, using process substitution:
while IFS= read -r line; do
  some_other_commands "$line"
  #variables set here remain valid afterwards
  #since this while-loop is not in a subshell
  #thus the last $line will remain set afterwards
done < <(some_commands)

With process substitution and the mapfile builtin, you can even populate an array and iterate over that:

mapfile -t arr < <(some_commands)
#synonym: readarray -t arr < <(some_commands)

for elem in "${arr[@]}"; do
  some_stuff_with "$elem"
done
# or:
for ((i=0; i<${#arr[@]}; i++)); do
  some_stuff_with "${arr[$i]}"
done

Nick Taylor • Oct 22 '21

Nice!

grendel • Oct 23 '21

When I have pushed to my remote from another machine, and made commits but forgot to pull first, I learned that to avoid an ugly and unnecessary merge commit, git pull --rebase is probably safer than trying to get around it with various combinations of git stash and git reset, because it yeeted one of my passwords away by accident :v

I also learned how (not) to set up nginx as a reverse-proxy to docker containers and how to use Jekyll

Nick Taylor • Oct 23 '21

Lisa Cee • Oct 23 '21

This week I learned about Frontity, a React framework for WordPress. WordPress still serves as the backend and database, but you can make components for the frontend with React. While Frontity isn't going to work for my planned project (I couldn't figure out how to add TailwindCSS into the mix), it's a tool that I'm glad I have played with.

Nick Taylor • Oct 23 '21

TIL!

Ben Halpern • Oct 22 '21 • Edited

I dug into signed exchanges a bit today. I was vaguely familiar before, but it clicked.

Nick Taylor • Oct 22 '21

Amrin • Oct 22 '21

crap i didn't learn anything new this week.

Nick Taylor • Oct 22 '21

No worries friend!

Amrin • Oct 22 '21

Thanks Nick ;)

Ben Halpern • Oct 22 '21

😮

Andrew McIntosh • Oct 22 '21

(Re)learning some PHP for a side project. It's been a few years and I never really knew PHP well in the first place. Getting reused to the syntax and learning about PHP 8 changes.

Nick Taylor • Oct 22 '21

Abu Mushonnip • Oct 23 '21

Well I just got insight and interested to learn new technology, that is ASP.NET Core 6 rc.2 which will be stable release in November.
This is my first time learn .NET stuff, Do you have any learning resources, suggestion or advice about it? (this is also my first time learn C#)
My past experience in web development is just Laravel and Django