In this week's episode of Programming By Stealth, Bart Busschots continues his instruction on learning more about how to use the jq language to query JSON files. We get into the thick of it as Bart teaches us three important jq concepts: filter chaining, operators, and functions.

To get there we learn about the literal values in JSON and jq and how only null and false are false. Armed with that, Bart explains the `not` function and once we put those concepts together, this ridiculous command will make perfect sense:

`jq -n 'true and true | not' # false`

I got such a kick out of that when I first read it in the shownotes earlier this week that I posted my enjoyment of it on Mastodon, and one of the actual developers of `jq` commented that he was excited to learn we were covering jq in Programming By Stealth!

The `any` and `all` functions are nearly as silly sounding but are equally useful. By the end of the episode, we can successfully query the Nobel Prize JSON file to show us all of the prizes won by anyone with the surname "Curie".

We even have three fun challenges at the end of this episode.

You can find Bart's fabulous tutorial shownotes at pbs.bartificer.net.

Read an unedited, auto-generated transcript: CCATP_2023_12_09

Join our Slack at podfeet.com/slack and look for the #pbs channel, and check out our pbs-student GitHub Organization. It's by invitation only but all you have to do is ask Allison!

After the last episode of Programming By Stealth where Bart gave us an intro to jq and the problems it can solve, this week we start to get our feet wet by learning how to extract data from JSON files. We learn how to descend into dictionaries and arrays, and how to slice arrays. Learn how jq will output sarcasm about "Bart Busschots" if you don't learn how to ask it for raw output. We even learn how to extract data from multiple files at once and how to extract multiple values from our JSON files. Finally, we learn about exploding arrays and how to suppress errors.

I think I really love data manipulation because I loved this episode.

You can find Bart's fabulous tutorial shownotes at pbs.bartificer.net.

Read an unedited, auto-generated transcript: CCATP_2023_11_25

Join our Slack at podfeet.com/slack and look for the #pbs channel, and check out our pbs-student GitHub Organization. It's by invitation only but all you have to do is ask Allison!

After our annual break from Programming By Stealth that happens at an unknown time for an unknown length every single year, Bart and I are back with a new episode of Programming By Stealth. Bart introduces us to a language called jq _and_ a terminal command called `jq` which together are used to help query JSON files, see "pretty versions of them, and also to manipulate them.

We don't learn a lot of commands but Bart walks us through a few examples to help illustrate why we care, or shall I say, "the problem to be solved"? I'm sold on the idea having just mucked about in a config files for homebridge this week.

You can find Bart's fabulous tutorial shownotes at pbs.bartificer.net.

Read an unedited, auto-generated transcript: CCATP_2023_11_18

Join our Slack at podfeet.com/slack and look for the #pbs channel, and check out our pbs-student GitHub Organization. It's by invitation only but all you have to do is ask Allison!

Bart Busschots joins us for Programming By Stealth with the final installment of our miniseries on Bash. He explains a few new concepts, but the real value of this installment and especially his fabulous tutorial shownotes is that he compiles a lot of info into some tables for us to use as reference for the future. As with all good programming, Bart is scratching his own itch - he wanted a single place to go to know which brackets mean which and which ones do you have to cuddle vs. not cuddle. He also wanted a table of the order in which Bash processes the seven distinct expansions.

We're closing out Bash but Bart has a new miniseries on the horizon to look forward to.

You can find Bart's fabulous tutorial shownotes at pbs.bartificer.net.

In Programming By Stealth, we've come to the end of our journey with Bash. I'll be sad to have it complete because as I tell Bart in this episode, I've really enjoyed it. Next time he will do a final bow-tying episode where he brings everything we learned together in one set of notes as a handy reference guide.

In this episode, he explains how functions work in Bash, and after about the 12th time he repeated it, I understand that functions we create in Bash work just like built-in functions such as `ls` or `cat`.

After walking us through some easy-to-follow scripts to illustrate this and show us the syntax, we go into a harder concept: scope. We learn that Bash does scope differently from pretty much every other language, and so he teaches us how to avoid spooky action at a distance because of this different way of dealing with scope. Protecting ourselves isn't actually hard but it is very important to understand why we need to do this.

You can find Bart's fabulous tutorial shownotes at pbs.bartificer.net.

In Programming By Stealth 152A Bart and I decided to hold off on the middle of the lesson he'd written up. That middle bit where he said to "put a pin in it" was about the use of `xargs`. I'm really glad we did skip it in the last installment. It's a pretty useful concept and deserved a lot more attention than it would have if we'd tried to cram it into that episode. The other good news is that Bart learned a bit more about _how_ `xargs` does its magic, so he is better able to explain it, and he updated the shownotes with a lot more detail and a great worked example.

As a teaser, the big problem `xargs` was designed to solve is that there are times when we want the data from the standard input stream (STDIN) to be passed to another command as one or more arguments.

You can find Bart's fabulous tutorial shownotes at pbs.bartificer.net.

Read an unedited, auto-generated transcript: CCATP_2023_07_08

I don't always make the time to pre-read the shownotes for Programming By Stealth but I never regret when I do make the time. That was especially true this week. In this installment, Bart Busschots takes us through his solution to the challenge from PBS 151, which was to print a "pretty" multiplication table using the `printf` command.

Being Bart, he didn't just make the columns line up nicely, he took it up a notch and added ASCII characters that build a nice border and corners around his table.

The reason I said it was good I pre-read the shownotes is that while nearly everything he explains in this lesson was a reuse of things he's taught us before, the commands are so dense in Bash that it was particularly hard to read and comprehend. We had also taken 4 weeks between lessons which made it even harder to remember.

Because I told Bart ahead of time that I was going to be stopping him to ask lots of questions, we decided to skip the one main topic he had planned to explain - `xargs`. This means that the next installment will start with `xargs` as Programming By Stealth 152B using the same shownotes. I'm really glad we did it this way because instead of you having to listen to a confused and thus frustrated Allison, the lesson flows well with me having time to ask the right questions.

You can find Bart's fabulous tutorial shownotes at pbs.bartificer.net.

This week's Programming By Stealth wasn't a heavy lift but I managed to get confused a couple of times anyway so expect lots of questions from me in this one. Bart started the show by telling us about a clever tip from listener Jill of Kent about how to detect when the Terminal talking to and from STDIN, STDOUT, and STDERR. Then we learn about how to use the `printf` command to make nicely formatted output. I especially liked that part because I love me some organized output.

You can find Bart's fabulous tutorial shownotes at pbs.bartificer.net.

When Bart and I recorded PBS 150 on Bash Script Terminal Plumbing, neither of us was happy with it. I got very confused in the middle, and Bart decided that his original strategy might have been flawed in which he assumed everyone had heard Taming the Terminal and remembered everything taught more than 4 years ago. He completely rewrote the shownotes and we re-recorded the entire episode. It was ever so much more fun and I really understood what he was teaching this time through. He also realized after we recorded that there was a bit of information he hadn't taught us which was crucial to being able to complete the challenge he had set for us. If you understood PBS 150 the first time through and want to jump right to the new part, I put a chapter mark in the audio file that will take you to where he explains `/dev/tty`.

We're proud to have done this because we are both of the same mind that we need to stay committed to the quality of what we're creating here, both for the current listeners and the future learners.

***

Bart and I took a few minutes upfront to high-five each other for 150 episodes of the Programming By Stealth Podcast. Then we quickly got to work.

Back in the Taming the Terminal podcast (at [ttt.bartificer.net/...](https://ttt.bartificer.net/), Bart taught us about stream redirection, or what he likes to call Terminal Plumbing. This was a long time ago and many folks may not have listened to that great series. Bart takes us through it again but from the perspective of writing Bash scripts that can do everything we can do in the Terminal. We learn about Standard Input (STDIN), Standard Output (STDOUT), and Standard Error (STDERR). We also learn how to bifurcate STDOUT and STDERR to produce desired results. He walks us through how to use the symbols `>`, `<`, and our friend the pipe `|` to redirect output from commands and files. I did get stuck for quite a while in a few spots here and there. Bart continues to try to convince me that if I'm confused, at least one other learner is as well, so hopefully making Bart find different ways to explain these things to help me will help you.

You can find Bart's fabulous tutorial shownotes at pbs.bartificer.net.

Join our Slack to talk to other Programming By Stealth learners by going to podfeet.com/slack.