HPR

Posted at 2026-05-17 19:14:19 relating to the show hpr4640 which was released on 2026-05-15 by Ahuka entitled Robert A. Heinlein

As you can tell I am a big fan so it was pleasure to start writing about him. But I am a fan of many of the older science fiction writers, and I have more to come on Heinlein as well as some other writers.

Posted at 2026-05-17 18:35:11 relating to the show hpr4637 which was released on 2026-05-12 by Vance entitled UNIX Curio #6 - at and batch

I happen to have a number of VMs set up that I use for testing, so I was able to do a quick check to see which distros have "at" and "batch" installed by default.

It turns out that Debian, Ubuntu, Raspberry Pi, Suse, and Alpine do not have it by default. Alma (a Red Hat clone), FreeBSD, and OpenBSD do.

While they can be installed later, it may be that they are not more commonly used now because you cannot rely on them being there as a standard feature.

I was struck by the thought that "batch" may be useful for things like testing software by being able to kick off a long series of tests that are run in the background while you get on with doing other things without these background tests affecting whatever else you are doing too much. Audio and video processing may possibly be the same.

Perhaps some other listeners could think up some creative ways of using "at" and "batch" and tell us about it in an episode in future. This sounds like it could lead to some interesting ideas.

Posted at 2026-05-17 18:08:18 relating to the show hpr4628 which was released on 2026-04-29 by Whiskeyjack entitled Nuclear Power Technology Follow Up

Thank you for your comment. Questions like the one that you asked are very helpful because they cause me to look into and think about things that I might otherwise have overlooked.

When doing the research to answer your question about MAGNOX reactor patents I was struck by some of the parallels between Open Source / Free Software and the early history of nuclear energy.

While this may seem like a stretch, in both fields we see how things like patents are more likely to hold technology back than they are to advance it, and how personal connections between people can matter more than the technology itself.

I have just finished the script for another follow up episode in this series and hope that people find this one interesting as well.

Posted at 2026-05-17 03:03:47 relating to the show hpr4637 which was released on 2026-05-12 by Vance entitled UNIX Curio #6 - at and batch

Nice to hear that others find "at" to be helpful! Perhaps some of these curios are not as obscure as I thought.

To delay running something on a personal system, I would probably be more likely to use "sleep [time] ; [command]" as a quick-and-dirty method. This would also put the output in the same terminal session. But I can see how "at" could be more elegant.

For rebooting, a lot of systems have the "shutdown" command (in looking around, it's far more common than I expected). This takes a time argument for when to execute the shutdown. So you could also use "shutdown -r 00:00" as a way to reboot your system at midnight (some implementations might differ on how the time is expressed). As with Perl, in the UNIX world often there's more than one way to do it!

Posted at 2026-05-17 00:24:23 relating to the show hpr4628 which was released on 2026-04-29 by Whiskeyjack entitled Nuclear Power Technology Follow Up

Liked too much. There are more nuances than I could expect. Thanks for answering my question!

Posted at 2026-05-17 00:22:01 relating to the show hpr4640 which was released on 2026-05-15 by Ahuka entitled Robert A. Heinlein

Great tips for writing. He chose well, ones without subjectivity, no further questions needed to answer with those pah-pum (direct) lines.

Nice to know Heinlein from your show. o/

Posted at 2026-05-16 19:41:04 relating to the show hpr4637 which was released on 2026-05-12 by Vance entitled UNIX Curio #6 - at and batch

I use at to schedule reboots for systems that have kernel updates installed, but I dont want to reboot right now.

Something like:
@midnight ENTER
reboot ENTER
CRTL-d

Posted at 2026-05-15 15:22:16 relating to the show hpr4618 which was released on 2026-04-15 by Whiskeyjack entitled Simple Podcasting - Episode 2 - Basic Filtering

I am glad you found this episode interesting, including the part about generating sine waves using FFMPEG.

I cover this topic again in hpr4658 Audio Revisited, which comes out on Wed 2026-06-10 and in which one of the topics I discuss is characterizing hardware such as speakers and microphones in order to understand their limits. It also helps to understand the limits of your own ears as well.

In that episode I also cover generating a "chirp" signal, which is a tone which sweeps across the audio frequency range from low to high, which is also useful in understanding hardware.

I can recall many years ago salesmen in stereo shops using special CDs which had these signals on them which they would use to demonstrate the capabilities of the high end speakers they were selling. If you have ever wanted to have such a thing for yourself, you can generate it using FFMPEG or Sox.

Posted at 2026-05-14 19:59:46 relating to the show hpr4618 which was released on 2026-04-15 by Whiskeyjack entitled Simple Podcasting - Episode 2 - Basic Filtering

Very interesting show. One thing in particular I find useful for testing speakers is the command to genererate a sine wave at various frequencies. I've tried the ffmpeg command version.

Posted at 2026-05-13 03:43:37 relating to the show hpr4637 which was released on 2026-05-12 by Vance entitled UNIX Curio #6 - at and batch

IMO, at and batch still have plenty of uses in things like scripts. It does provide a POSIX way to schedule a task in the future, which could be useful for scripts that want to offset certain effects without having to run its own daemon. Something like batch could also be used with cron as a sort of "run at some point after this time" trick, so if you happen to be doing something intensive at that time then it can put it off until its more optimal.

Also, at can just be used to plain run some process a few hours from now, its pretty useful for like starting an intensive process overnight without having to remember to start it before going to bed

Posted at 2026-05-12 19:36:04 relating to the show hpr4424 which was released on 2025-07-17 by Archer72 entitled How I use Newsboat for Podcasts and Reddit

I found HPR through this old program called gPodder, its reccomended podcasts list has it in there and it seemed like a cool thing to tune into

Posted at 2026-05-12 17:18:20 relating to the show hpr4631 which was released on 2026-05-04 by HPR Volunteers entitled HPR Community News for April 2026

Thanks Dave for encouraging me to record an episode, I hope to able to do so soon. Currently I have very limited access to electronic devices (30 mins every 3 days), except for an MP3 player

Posted at 2026-05-12 17:16:07 relating to the show hpr4424 which was released on 2025-07-17 by Archer72 entitled How I use Newsboat for Podcasts and Reddit

I found about HPR from another podcast, I think it was called Linux UK LUG cast or something. It ended anyway

Posted at 2026-05-12 01:03:12 relating to the show hpr4607 which was released on 2026-03-31 by Vance entitled UNIX Curio #3 - basename and dirname

In a recent conversation, a friend pointed out that historical BSD versions were not necessarily developed or released in numerical order. Instead, 2.xBSD versions were created to run on the PDP-11 while 3BSD and 4.xBSD ran on the VAX (until support was added to 4.x for other processors); both evolved alongside each other.

In the audio for this episode, I implied that the 'basename' utility first appeared in BSD in version 2.9 (1983), while it actually was in 3BSD from 1979, shortly after Bell Laboratories' Seventh Edition UNIX came out. Similarly, I incorrectly said that the first BSD 'dirname' appeared in was 4.4 (1993), when it was in the Net/2 release from 1991. Sorry about that!

Probably others like me have fallen into the trap of assuming a larger version number always came later, but I should have paid closer attention to dates. (Discussion of the history does not appear in the show notes above, just the audio.)

P.S. Glad you are liking these, xmanmonk! More are on the way.

Posted at 2026-05-08 22:02:23 relating to the show hpr4587 which was released on 2026-03-03 by Vance entitled UNIX Curio #1 - Shell Archives

Glad you enjoyed it, Dave! I did work at one place that had a color thermal transfer printer and got to use it a couple times.

They also had a film recorder, though I never used it myself. This would put a computer-generated color image onto photographic film. After being developed by a photo lab, the resulting film slides could then be shown using an ordinary slide projector. Very fancy stuff, until digital projectors became available.

Posted at 2026-05-07 18:18:05 relating to the show hpr4587 which was released on 2026-03-03 by Vance entitled UNIX Curio #1 - Shell Archives

I'm way behind with listening to HPR episodes, so sorry for the late comment!

In the early 1990s the university I worked for (in Edinburgh) installed DECAthena, a commercial version of the MIT Athena Project. As a consequence I ended up with a DEC MIPS workstation on my desk running Ultrix.

We had a USENET feed by then and we would download stuff like pictures from various newsgroups, using a tool that I assume was shar. Files arrived as a series of posts with encoded contents, which we would reassemble in a newsreader and decode.

I had forgotten about this! Thanks for the reminder :-)

Printing coloured images was challenging in those days (for us anyway), and I recall we had a Thermal Wax printer to do it!

Dave

Posted at 2026-05-06 20:35:49 relating to the show hpr4634 which was released on 2026-05-07 by operat0r entitled Upgrade Failsause

Hi YourName,

We already received a report that there were problems with the audio, and as such we replaced the episode with another from operat0r from the back up queue.

As you are listening to this before it is released I assume it's coming from the Future Feed. You will need to refresh your cache on the podcatcher you are using for to get that episode. Thankfully this is only on the future feed, and the listeners to the main feed will get the updated episode without issue.

Ken

Posted at 2026-05-06 20:05:43 relating to the show hpr4634 which was released on 2026-05-07 by operat0r entitled Upgrade Failsause

I guess I had the mic in my ear but it was not working so you got the mic in my pocket I guess ... sorry folks

Posted at 2026-05-05 09:00:00 relating to the show hpr4631 which was released on 2026-05-04 by HPR Volunteers entitled HPR Community News for April 2026

Sorry if you feel under pressure. Take your time, hope it goes better soon.

Posted at 2026-05-04 18:47:39 relating to the show hpr4631 which was released on 2026-05-04 by HPR Volunteers entitled HPR Community News for April 2026

thanks for the episode suggestion about the process programs but i still dont really want to work on any episodes im still recovering from the stuff that happened feb/march

Posted at 2026-05-04 05:13:02 relating to the show hpr4631 which was released on 2026-05-04 by HPR Volunteers entitled HPR Community News for April 2026

Ken Fallon had said in response to something that I had said in HPR 4628 with regards to me wanting to avoid subjects that some people may view as being politically controversial. He had made the same statement in the previous community news with regards to a comment that I had made in response to another listener.

I first want to clarify that HPR 4628 was recorded and uploaded before Ken had stated this the first time, so when I said this in HPR 4628 it was without the benefit of his earlier clarification on this.

My assumptions were based on what I observed as being the community practice of posting fairly low stress topics that people can relax to and not getting into flame wars. I had assumed this was an unwritten rule that had arisen through common practice.

I was going to attempt to very briefly answer in this comment brian-in-ohio's question on the relative safety of different types of electric power generation. However the answer was getting long enough that I suspect that one of the community news presenters would probably tell me to put it in an episode. I will therefore make a short episode on it and submit it after the episodes I currently have in the schedule.

Spoiler alert however, so far as I can determine, the data upon which to make any sort of objective relative ranking of electric power generation sources simply does not exist in a form which would allow an apples to apples comparison across all industries.

The net result is that any discussion of this topic comes down to belief and opinion rather than provable fact.

I will however attempt to provide some context in which to think about these questions.

Posted at 2026-04-30 18:58:50 relating to the show hpr4627 which was released on 2026-04-28 by Vance entitled UNIX Curio #5 - Faster, Pussycat! Kill! Kill!

Vance: The Ctrl-Alt-Esc keybind is actually calling a binary, xkill, and it's pretty easy to just set a keybind in your desktop enviroment to call it. On my system, its bound to shift+alt+x, since its really easy to hit with only my left hand.

Also, I figured those weren't POSIX but they're still useful for day to day terminaling and little personal scripts

Posted at 2026-04-29 20:58:44 relating to the show hpr4627 which was released on 2026-04-28 by Vance entitled UNIX Curio #5 - Faster, Pussycat! Kill! Kill!

Antoine: Not sure if they still support it, but under some window managers you used to be able to press Ctrl-Alt-Esc and the cursor would turn into a large X or a skull and crossbones. You could then click on a window to kill the program that owned it. Similarly, Ctrl-Alt-Backspace would end the entire X session. I think this is no longer common and it might not even be possible under Wayland.

candycanearter07: Very cool, thanks! I've used 'killall' a bunch but was not aware of 'pgrep', 'pkill', and 'pidwait'. They look to have some neat capabilities - maybe you could consider doing an episode on them? (Of course, none of these are in POSIX, so you wouldn't want to use them in a script unless you knew the systems it would be used on have those utilities.)

Posted at 2026-04-29 15:14:31 relating to the show hpr4627 which was released on 2026-04-28 by Vance entitled UNIX Curio #5 - Faster, Pussycat! Kill! Kill!

I didn't know about kill -0, thats a cool POSIX way to check if a process is existing or not. In most of my scripts, I used the p* commands instead (pgrep, pkill, pwait) since usually getting a specific process by pid didn't matter and they all support passing a pidfile directly with -F

Posted at 2026-04-29 11:57:27 relating to the show hpr4627 which was released on 2026-04-28 by Vance entitled UNIX Curio #5 - Faster, Pussycat! Kill! Kill!

Nothing to aggregate, only to say– loved learning about Kill. In my first times of Linux, maybe a problem of mine, I had to use it almost daily (in the main purpose, not knowing until now that the command can pause or only return the running status (: ).
I found it magical, because the ctrl+alt+del of Windows was not always responsive in times of trouble, but, in Linux, accessing a terminal to uss "killall X" (or whatever program) was always possible.
Thank you, Vance, 4dshow.

Posted at 2026-04-28 17:16:54 relating to the show hpr4618 which was released on 2026-04-15 by Whiskeyjack entitled Simple Podcasting - Episode 2 - Basic Filtering

I already have the 5 second audio sample that I need from your HPR 4637 episode from the MP3 release, but I thought it would be polite to ask you first before using it as we were already corresponding in these comments.

I have most of the script written for a new HPR episode and will begin recording the dialogue and making the audio samples used to illustrate each point. I will describe in detail what I did to the sample from your podcast in that episode and show a before and after example.

This new episode is entirely inspired by comments from listeners, and your comment describing a click problem provided a very interesting subject for discussion in it. Thank you for your feedback on this.

Posted at 2026-04-28 00:43:11 relating to the show hpr4618 which was released on 2026-04-15 by Whiskeyjack entitled Simple Podcasting - Episode 2 - Basic Filtering

Thanks for your ideas! Looking at the Ogg/Opus/MP3 files on HPR, I see that they have some additional noise during pauses that makes the click removal filter in Audacity less effective. On the original WAV file, I *was* able to remove most of the tapping noise by applying that filter to pauses with a Threshold value of 50 and a Max Spike Width of 30. Trying the same values on pauses in the MP3 file was less effective, but did improve things a little bit.

I agree that applying the click filter to the sections where I'm speaking produces undesirable distortion. It would be possible to manually highlight just the pauses and remove clicks from each one, but that would be tedious. I considered blanking out those areas, but it would be just as tedious and I thought it might sound weird for there to be total silence.

However, your suggestion of using ffmpeg's agate filter would eliminate the problem of having to manually highlight the pauses. I see that it doesn't totally zero out the waveform, just reduces it, so it shouldn't sound weird.

I would be happy to send you a WAV or FLAC file to play around with, and you are welcome to use as much of this episode as you like in your own work. E-mail me at the address on my host page.

Initial testing seems to indicate that it was likely my mobile phone that caused the problem to begin with. If that is the case, it's easy enough to get rid of the problem at its source by moving it away from the microphone (it was in my shirt pocket) or just turning it off.

Posted at 2026-04-27 00:48:11 relating to the show hpr4618 which was released on 2026-04-15 by Whiskeyjack entitled Simple Podcasting - Episode 2 - Basic Filtering

I had a look at your HPR 4637 episode to see what the "clicks" were like. I did some experiments to try to find a technique which could remove the clicks.

The "click removal" effect in Audacity does nothing useful to deal with this. The same was true for most of a number of other common filter techniques that I tried. The ones which did have an effect on the clicks introduced noticeable distortion in the voice which was more of a problem than the clicks.

What does work is the "noise gate" effect (which is agate in ffmpeg). You set a threshold in dB and any part of the signal which falls below that level is suppressed to zero. In other words, quiet parts of the audio are made quieter. I set a threshold of -20dB and all of the clicks were completely removed without introducing distortion in the voice signal.

In a few spots, short initial syllables on a few sentences were also cut out, but I didn't spend any time adjusting parameters to get it perfect. I suspect that another solution to this would be to not apply the effect on those few parts of the audio where this happens.

Would it be alright with you if I used a short (5 second) clip of your podcast as a noise sample in my own upcoming episode on audio filtering? This is not a noise problem that I can easily recreate and it would make for an interesting problem and solution to address.

The more I look at things the more I am convinced that there is no one size fits all solution to audio problems, only collections of tools that we can keep in our toolboxes.

Posted at 2026-04-26 23:55:45 relating to the show hpr4616 which was released on 2026-04-13 by Trollercoaster entitled Thoughts about age control and further suggestions

Hey, Trollercoaster, I'm a member of the Legislative in Atlantis. (The underwater one.) Nevertheless, we are going to emerge soon, the making of the e-banners can begin.
(Our language is the Atlantean, we don't understand if not it — the translation, if you can read it, is in real time, by scanning of the legitimate eyes that should see the message.)

Parlament members can't roll for the Executive though. Never. You, if you can read, may come to the Palace. If so, please just let me know so I can wake both eyes of the editorial whales for the making of your Presidential Propaganda.

Ahibvederti! **–end_of_italic_atlantean_intimate_translatxxxx___**

Posted at 2026-04-25 15:37:22 relating to the show hpr4616 which was released on 2026-04-13 by Trollercoaster entitled Thoughts about age control and further suggestions

Hello Antoine,

please notify me in what state you are going to submit that proposal. I will move to that state and run around with a banner "Antoine for president!"

Hey Candycanearter07,
I don't get it. Do you hate hackers?