HPR Comments

Archer72 says: re: Suggestion for Linux Curio

RE: hpr4707::2026-08-18 UNIX Curio #12 - expr by Vance
00:24:27 Listen in ogg, opus, or mp3 format.
ASCII Star Wars is another.

There is a command to telnet to towel.blinkenlights.nl

Here Star Wars plays in a terminal.

Trollercoaster says: Suggestion for Linux Curio

RE: hpr4707::2026-08-18 UNIX Curio #12 - expr by Vance
00:24:27 Listen in ogg, opus, or mp3 format.
I've been enjoying your episodes of Linux Curio - and they're on my favlist.

But you are way too serious. Maybe an episode on the fun gems of the linux terminal could be cool. I'm pretty sure we all know cowsay already, but I once remember I saw a choo choo train too.
Maybe there are other perfectly useless but fun linux commands out there?

Vance says: Thanks for the ideas

RE: hpr4707::2026-08-18 UNIX Curio #12 - expr by Vance
00:24:27 Listen in ogg, opus, or mp3 format.
First off, I just want to give fair warning that the future cadence is likely to be closer to one a month rather than one every two weeks. Someone else has already submitted hpr4717 so there will be some extra time between episodes. That will be true for other future episodes as I have mostly exhausted subjects I am familiar with, so these will need more research than past ones.

I appreciate the value in adding some more levity, but it's difficult as my nature tends to be more serious. The next episode (still being written) is a bit more frivolous, but not really humorous so far - will think about how I might re-write it to bring that in.

Good point about looking in different places - it recently occurred to me that I should be more open to utilities outside POSIX. I have identified a few that came from BSD and gained widespread use despite never being standardized, which might be interesting.

I'm surprised to hear that "xeyes" is even present on a system using Wayland. Of course the design of Wayland means "xeyes" cannot track the mouse pointer when it's outside the "xeyes" window, kind of defeating the point. Like with BSD, I'll start looking more into X-related programs to see if there are any that would be a good fit.

Very much appreciate the input, glad you are enjoying these!

Vance says: dc

RE: hpr4707::2026-08-18 UNIX Curio #12 - expr by Vance
00:24:27 Listen in ogg, opus, or mp3 format.
Thank you both! Whiskeyjack, you do have a good point. Thirty years ago when I was first learning about UNIX, 'dc' was often included in introductory materials, which is why I said it isn't obscure. However, I probably didn't fully appreciate how the situation has changed since then.

To be blunt, I'm still not a fan of RPN or 'dc' and I don't feel very motivated to dig any deeper into it. But I suppose one never knows; maybe one day it might catch my interest. Actually, regarding the HP calculator I described, its case was as fascinating to me as the device itself - it was the first place I had ever seen Velcro hook-and-loop, which in the 1970s seemed magical!

Whiskeyjack says: HPR4707 Unix curio - Stack Machines

RE: hpr4707::2026-08-18 UNIX Curio #12 - expr by Vance
00:24:27 Listen in ogg, opus, or mp3 format.
I prefer using normal infix notation over RPN, but one of the easiest ways of making an interpreter is to create what is called a "stack machine" which does everything on a stack. Data values get pushed onto a stack, and operators work on the values in the stack. Forth is probably the best known stack oriented programming language.

RPN translates very easily to a stack machine, and dc clearly works with a stack because it gives the error "dc: stack empty" if you make an error such as not providing enough arguments.

I don't know the history of either HP calculators or dc, but I suspect that both may have used RPN more for the reason that it was easiest to implement it that way than because anyone thought it was better from a human perspective.

In episode 4 of my series on industrial controls (HPR4738) I talk about the stack based boolean logic interpreter in the Siemens S5 series PLCs. The concept is fundamental to most industrial controls, although it is often hidden from view.

The Postscript language used in PDF files is also a stack based programming language, so the concept is fairly widely used.

I find the subject of stack based interpreters to be fascinating even though they are not my preferred way of writing programs.

Whiskeyjack says: HPR4707 Unix curio - dc

RE: hpr4707::2026-08-18 UNIX Curio #12 - expr by Vance
00:24:27 Listen in ogg, opus, or mp3 format.
Having just read some of the background of dc, I would have thought that it would have been worth a "Unix Curio" episode all on its own.

It is obscure in that most people probably didn't know that it exists, it uses RPN notation, which few people use, it didn't become part of the POSIX standard, and it has an interesting relationship to the more commonly used bc.

I might be worth making this a subject of a future Unix Curio.

Whiskeyjack says: Obscure X Window programs

RE: hpr4707::2026-08-18 UNIX Curio #12 - expr by Vance
00:24:27 Listen in ogg, opus, or mp3 format.
Don't forget the obscure X Window programs as well. People did a lot of silly things with the X Window system that seem to have faded away and been forgotten. I'm not sure it is even possible to do some of these things with Wayland.

Here's a few:
XEyes
XNeko
XRoach
XSnow
GLXGears

I notice that XEyes is installed on my PC running Ubuntu 24.04, but I have no recollection of installing it, so perhaps it comes by default. I had no idea it was there until I just tried it now.

It doesn't seem to work quite correctly with Wayland, as it is confined to a single window.

Some of the others can still be installed, but I haven't tried that.

Where these things came from and why they were created could be an interesting story if someone were to research it.

Whiskeyjack says: Reply to Vance on episode research

RE: hpr4707::2026-08-18 UNIX Curio #12 - expr by Vance
00:24:27 Listen in ogg, opus, or mp3 format.
Vance - I have done two 8 part series and one 4 part series so far.

I find that researching, writing, and recording several closely related subjects at the same time is much less work than an equal number of unrelated episodes. To put it another way, my series are much less work on a per episode basis than the same number of unrelated episodes done sequentially.

I also try to target a length of about 20 minutes at most, although I find myself going over that sometimes. If it gets longer than that, then I look for ways to split it up.

By writing, editing, recording, and reviewing in batches, I can have several months worth of material recorded ahead of when it is released. For example, my current series runs until the end of November, which gives me plenty of time to research a couple of more related episodes that I have planned.

I'm not sure how it would work out with your Unix Curios, but if you can try to plan out working on related subjects together at once (e.g. X Window oddities) and then split the material into separate episodes, you may find that to be much less work than preparing and recording them one at a time.

Of course you are doing this for fun and so will do whatever you wish whenever you wish, but perhaps the above will give you some ideas that can help.

candycanearter07 says: re: Suggestion for Linux Curio

RE: hpr4707::2026-08-18 UNIX Curio #12 - expr by Vance
00:24:27 Listen in ogg, opus, or mp3 format.
the train one is called "sl" (steam locomotive) and is specifically designed to prank you for typing ls too fast

the go-to silly program that theres a million articles about is "hollywood", and "genact" is another silly one that infinitely outputs garbage that looks productive, but at that point thats straying from the built in programs so it probably wouldnt be covered in THIS series. maybe you could make a secondary series about interesting non-standard packages that may or may not be useful

candycanearter07 says: re: re: Suggestion for Linux Curio

RE: hpr4707::2026-08-18 UNIX Curio #12 - expr by Vance
00:24:27 Listen in ogg, opus, or mp3 format.
id argue that that is more of a internet thing than a command line thing at that point?

xmanmonk says: Another great show

RE: hpr4707::2026-08-18 UNIX Curio #12 - expr by Vance
00:24:27 Listen in ogg, opus, or mp3 format.
I typically use bc or the kde calculator, but there was some stuff here I either forgot or didn't know! Thanks for the info!

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HPR4707: UNIX Curio #12 - expr