Comments
Vance says: Thanks, everyone
RE: hpr4747::2026-10-13 UNIX Curio #13 - Replacements for cat by Vance00:25:46 Listen in ogg, opus, or mp3 format.
Wow, a lot going on here in the comments. I appreciate it!
Whiskeyjack: Can't believe I didn't think of 'tac' or 'rev' when putting this together. While they are not in POSIX, they are certainly widespread. I honestly have never encountered 'tsort' before - will look into it and see if I can make anything out of it.
candycanearter07: I haven't checked; some implementations of 'head' might support +1, but POSIX does not require it. I always thought of 'tail -f' as being well known, but maybe should revisit that. In practice, I generally use 'less' with the 'F' command instead of 'tail -f' these days, but sometimes it's not available.
Archer72 says: hpr4741 :: HPR Community News question
RE: hpr4717::2026-09-01 Visit with a blind Ham operator by Archer72from the series HAM radio.00:05:04 Listen in ogg, opus, or mp3 format.
Hi Ken and Kevie,
I heard your question about the antenna height in the Community News. The approximate antenna total height is indeed 15 metres, with the whip part of the antenna around 5 to 6 metres.
Cheers,
Archer72
archer72 says: xmanmonk
RE: hpr4747::2026-10-13 UNIX Curio #13 - Replacements for cat by Vance00:25:46 Listen in ogg, opus, or mp3 format.
Hi xmanmonk,
Do you have interests to hackers of your own?
If so, HPR would like an introductory show. :-)
Cheers,
Archer72
candycanearter07 says: head tail and grep
RE: hpr4747::2026-10-13 UNIX Curio #13 - Replacements for cat by Vance00:25:46 Listen in ogg, opus, or mp3 format.
cool ep!
i basically already use head and tail as cat for super long files that have important data at the start/end, also i use an alias to replace cat with batcat
ill also point out the same trick can be used with head since it also supports +1 to print up to the last line in the file
i think a curio on tail would be useful since one of its "hidden" functions (-f, or --follow) is so incredibly useful i wish it was talked about more its amazing for following log files
also also grep is slightly better than cat at catting every file in a directory, since you can use grep -r '' . to print everything recursively, as opposed to cat * which only prints non-hidden files in the current dir
Windigo says: Key phrase
RE: hpr4749::2026-10-15 murph gives a presentation talk about Hacker Public Radio at the OLF conference by murph00:37:45 Listen in ogg, opus, or mp3 format.
This was an overall fantastic introduction to HPR and the process of recording an episode, but I particularly loved the section about how to start recording - and how much preparation and thinking should go into it.
I think I need the phrase "think, to taste" engraved on a plaque.
0xf10e says: More knowledge
RE: hpr4726::2026-09-14 Trurl's intro show by Trurlfrom the series How I got into tech.00:38:45 Listen in ogg, opus, or mp3 format.
That's an interesting bit at the end: There's more knowledge than humanity can archive (right now).
I've wondered if mankind kinda needs to grow up to be ready for certain ideas which you can not force upon them to accept too early. Like Epicurus' description as everything being made of "atoms" or even Marx' socialist utopia (not the "actually existing socialism" type) becoming reality.
Whiskeyjack says: Style and delivery
RE: hpr4746::2026-10-12 Monotone by Lee00:11:42 Listen in ogg, opus, or mp3 format.
To get a good comparison, you would need to compare podcasts that are similar in terms of content. Style and delivery should match the subject, not adhere to some artificial average.
For example, a podcast that mainly consists of two people arguing about something will naturally have greater pitch variation than a podcast that is mainly about someone describing the intricate details of "sed" options.
Having someone speak in excited tones about the "--follow-symlinks" option would not improve the quality of the show from the user perspective.
Given that it is possible to measure pitch variation numerically, it would not surprise me if it were to be possible to process speech to artificially increase the pitch variation in order to normalize that figure, much like is done for audio loudness. That may make for an interesting experiment for someone. That could then be analyzed subjectively to see if the result sound unnatural in the context of the subject being discussed.
Whiskeyjack says: tac and rev
RE: hpr4747::2026-10-13 UNIX Curio #13 - Replacements for cat by Vance00:25:46 Listen in ogg, opus, or mp3 format.
If you use tac twice on a single file, you get the same output as the original file.
So:
tac sample.txt | tac > tactwice.txt
This does not work however if you do this with multiple files as the second operation is on the whole file instead of individual input files.
If you use rev twice on multiple files, then you get the same output as using cat.
rev *.txt | rev > rev.txt
Of course this only works for simple text files.
As a suggestion for a future episode, have you covered tsort yet?
xmanmonk says: Great!
RE: hpr4747::2026-10-13 UNIX Curio #13 - Replacements for cat by Vance00:25:46 Listen in ogg, opus, or mp3 format.
Another great episode! Certainly keeps the old brain thinking!
archer72 says: second that
RE: hpr4746::2026-10-12 Monotone by Lee00:11:42 Listen in ogg, opus, or mp3 format.
Hi candycanearter07,
I second the opinion that 'monotone' can be positive, as I conveys the information or story clearly.
Cheers,
Archer72
archer72 says: tee tip
RE: hpr4747::2026-10-13 UNIX Curio #13 - Replacements for cat by Vance00:25:46 Listen in ogg, opus, or mp3 format.
Hi Vance,
Thanks for the series and this particular thought experiment. It is one that I will go back to for shownotes reference.
A tip on 'tee' is to use 'tee -a myfile' which append to the stated file.
Cheers,
Archer72
candycanearter07 says: interesting!
RE: hpr4746::2026-10-12 Monotone by Lee00:11:42 Listen in ogg, opus, or mp3 format.
i dont understand a lot about audio processing but i think you explained it well! i dont get why HPR being more "monotone" is inherently a bad thing, since its pretty explicitly supposed to be people NOT specializing in entertainment (ie not already trained to speak upbeat) and it doesnt really matter if the actual content is interesting!
archer72 says: robots
RE: hpr4738::2026-09-30 Programmable Logic Controls - Episode 4 by Whiskeyjack00:29:37 Listen in ogg, opus, or mp3 format.
Hi Whiskeyjack,
I'll see what I can pull together, but it may take a while to jog my old memory. Though it has only been 3 years, I find that better notes would have been helpful.
Cheers,
Archer72
archer72 says: conference
RE: hpr4745::2026-10-09 BruCON interview 1: The BruCON organization by Kristofffrom the series Interviews.00:36:26 Listen in ogg, opus, or mp3 format.
Hi Kristoff,
Thank you sharing your experience at the conference. BTW, the audio in this interview sounded just right.
Cheers,
Archer72
archer72 says: Fellow radio enthusiast
RE: hpr4685::2026-07-17 Listening to SSB stations in the early 1980s by Lennart Benschopfrom the series HAM radio.00:15:12 Listen in ogg, opus, or mp3 format.
Hi Lennart and Lucinda,
Ask a Ham radio enthusiast, I have dabbled in shortwave and enjoyed the show. This is one that I will need to hear again. From Kentucky I have received RTÉ National Television and Radio on a single 30 foot wire.
https://www.rte.ie
Lucinda, what does a Field Scientist and Analog builder build and study? This would definitely be of interest to hackers. :-)
Cheers,
Archer72
Whiskeyjack says: Reply to Archer72 on robots
RE: hpr4738::2026-09-30 Programmable Logic Controls - Episode 4 by Whiskeyjack00:29:37 Listen in ogg, opus, or mp3 format.
Industrial robots have their own controllers which are distinct from PLCs in terms of how they work and are programmed. A very typical configuration for a complex manufacturing cell would be to have a PLC coordinating the overall cell plus controlling various parts of it which are not part of the robot.
The PLC would then tell the robot when to do its job, and the robot would tell the PLC when it was done in a handshake process.
Some robot manufacturers offer robot controllers which have PLC functionality integrated into them. I haven't worked with these, but it is a pretty straightforward feature to have.
In episode 8 in the series I talk about soft logic systems. You will see that running PLC type software on other hardware is in fact quite possible and all the same PLC concepts apply. If you understand PLCs, you will understand logic systems embedded in other controllers as well. You simply need to have an operating system running the different systems which can then communicate with one another and it can be possible to have robot controller software and PLC logic software running on the same embedded computer.
If you have some experience with industrial robots or with their drive systems, perhaps you could do an episode on them for the rest of us?
Kevin O'Brien says: Some additional information
RE: hpr4703::2026-08-12 Ebooks and Audiobooks by Ahuka00:07:59 Listen in ogg, opus, or mp3 format.
Your prices on Kobo readers look accurate to me. In fact I paid 169.59 US for the Kobo I ordered, which includes Michigan Sales Tax. Then when it was delivered the Fed Ex delivery guy said I needed to pay over $300.00 US for the tariff. I don't recall the precise amount because I never paid it. I told Fed Ex to take it back and refused delivery. It may have been a mistake by Customs, but that is what happened.
archer72 says: lightning safety
RE: hpr4762::2026-11-03 Surviving the Strike: A Host’s Tale of Lightning by operat0r00:11:45 Listen in ogg, opus, or mp3 format.
Hi operat0r,
Have you considered using a lightning proximity app? There is one that I have been using (not FOSS), My Lightning Tracker Pro, that I was introduced to by a fellow Ham operator.
https://play.google.com/store/apps/details?id=com.jrustonapps.mylightningtrackerpro
The only purchase in the app is a small donation to remove ads.
The FOSS version that I have yet to try is Blitzortung Lightning Monitor
https://f-droid.org/packages/org.blitzortung.android.app
Cheers,
Archer72
Archer72 says: PLC relevance
RE: hpr4738::2026-09-30 Programmable Logic Controls - Episode 4 by Whiskeyjack00:29:37 Listen in ogg, opus, or mp3 format.
Hi,
When I started listening to this series, I remembered that in a previous job being told that PLC's were not relevant anymore. And this was at a company that dealt with spindle and servo drives for industrial robots. Little did he know that I was moving to Toyota country (Kentucky), where PLC's were widely used. While I am not in the industry at the moment, this has still been an intriguing and timeless series. I would also think that robotics and PLC's would go hand in hand.
Thanks for all the effort in these episodes.
Cheers,
Archer72
Antoine says: Yahp.
RE: hpr4739::2026-10-01 Happy by shower # 3 by Antoine00:04:54 Listen in ogg, opus, or mp3 format.
Hey, Candycanearter07.
I feel for you. Hope it does good. Yahp.
(I always read your name as candy-cane-eater, like someone who eats something sweet. Only now I paid attention that it's not eater. But I don't know what arter is, and it is not earter, because someone from earth would be earther.) Only thought out loud.
Kevin O'Brien says: I enjoyed doing it
RE: hpr4703::2026-08-12 Ebooks and Audiobooks by Ahuka00:07:59 Listen in ogg, opus, or mp3 format.
I like being able to point people to resources other than Amazon.
Whiskeyjack says: Background noise in interview
RE: hpr4742::2026-10-06 OLF Call for presentations open by Ken Fallon00:53:53 Listen in ogg, opus, or mp3 format.
There have been a few comments on background noise in the interview in HPR4742.
Background noise outdoors and in public spaces in general are probably inevitable unless you have a professional grade sound crew and equipment. I did not personally find the background noise in this episode to be a problem in terms of understanding it and I see nothing wrong with it.
If anyone has a similar sort of recording, do not let this sort of noise discourage you from posting it. We will listen to it and enjoy it if the content is good.
I don't know what sort of, if any, filtering was done for this episode. However, too much filtering can be worse than no filtering at all as it can distort the voice signal plus it can actually inject more background noise than it removes. I am not implying this is the case here, I am just pointing out that there are limits to what you can do when recording in a difficult location or in post-processing.
I address filtering in my series on Simple Podcasting, which are HPR4608, 4618, 4638, and 4648.
In HPR4658 - Audio Revisited, I collect and compare a series of sound samples under various conditions with various equipment and then apply various audio filters. This shows that filtering comes down to making a balanced judgment on reducing background noise versus introducing distortion in the voice signal.
However, I am not familiar with auphonic.com. Perhaps Ken Fallon could to an episode on his experience using that method and how well he felt it worked. That would perhaps help other contributors in similar circumstances.
Whiskeyjack says: Reply to Archer72 on 8052AH Basic
RE: hpr4748::2026-10-14 Programmable Logic Controls - Episode 5 by Whiskeyjack00:21:13 Listen in ogg, opus, or mp3 format.
Thank you for the comment, Archer72. I have added a note to my podcast TODO list to make an episode on Basic Modules and on the 8052AH Basic chip in general.
It should come out after episode 8 in the current series.
If you have any other PLC related topics that you would like me to address, please post a comment below one of the episodes. I have made several episodes on other topics in response to listener questions or comments.
Archer72 says: Re: An HPR listener: Events.
RE: hpr4742::2026-10-06 OLF Call for presentations open by Ken Fallon00:53:53 Listen in ogg, opus, or mp3 format.
Hi,
I second Ken on the idea of taking the raw audio and processing out the fume extractor noise. This process would make a great episode, or even a few on how to filter out specific noise such as this.
Archer72
Archer72 says: Basic modules
RE: hpr4748::2026-10-14 Programmable Logic Controls - Episode 5 by Whiskeyjack00:21:13 Listen in ogg, opus, or mp3 format.
Hi Whiskeyjack,
In the community show comments, you mention knowledge of the 8052AH Basic chip, which would make a great follow-up show.
Archer72
Whiskeyjack says: Second reply to mechatrocity and archer72
RE: hpr4708::2026-08-19 Programmable Logic Controls - Episode 1 by Whiskeyjack00:19:52 Listen in ogg, opus, or mp3 format.
If you like the series on PLCs, the best thing to do is to comment on each episode as it comes out. This will help to bring it to the attention of more listeners.
If there is something in particular in an episode that you would like to hear more about, then post a comment requesting a follow up on that subject. I will then do a follow up episode dealing with those questions if I am able to answer them.
In one of my previous series, I ended up doing an additional two follow up episodes dealing with listener questions.
Whiskeyjack says: Reply to mechatrocity and archer72
RE: hpr4708::2026-08-19 Programmable Logic Controls - Episode 1 by Whiskeyjack00:19:52 Listen in ogg, opus, or mp3 format.
I think that adding a tag at this point would be up to the HPR janitors, as the full 8 parts of the series is already uploaded.
Perhaps the community news presenters could offer their suggestions on this when they read the community news at the end of the month.
If you don't wish to wait that long, you may try raising the issue on the mailing list.
archer72 says: Re: Adding a PLC tag
RE: hpr4708::2026-08-19 Programmable Logic Controls - Episode 1 by Whiskeyjack00:19:52 Listen in ogg, opus, or mp3 format.
Hi mechatrocity,
I second adding a 'PLC' tag and also 'Programmable Logic Controls'. It wouldn't take up much in the data table. ;-)
Also, I believe there is still a place on the HPR Hub to add needed tags.
Archer72
Dave Morriss says: Didn't know 'dc'; knew of 'expr' but never got on with it!
RE: hpr4707::2026-08-18 UNIX Curio #12 - expr by Vance00:24:27 Listen in ogg, opus, or mp3 format.
Hi Vance,
I'm getting caught up on HPR shows, and just heard this one. Sorry I'm late!
I'd never come across 'dc' before, but in the 1970's I built a Sinclair Scientific calculator (from a kit), and it used RPN (and was very slow). I have installed 'dc' today in fact, and it feels a bit nostalgic using it.
I have encountered 'expr', but never found it all that useful. As you say, the later developments in shells like '$((42*2))' have made doing arithmetic a lot simpler. I'm primarily a Bash user to tend to prefer "Bashisms".
Thanks for the detailed analysis of the subject.
Dave
mechatrocity says: Adding a PLC tag to these episodes and creating a 'series'
RE: hpr4708::2026-08-19 Programmable Logic Controls - Episode 1 by Whiskeyjack00:19:52 Listen in ogg, opus, or mp3 format.
Love this episode as an intro, and I'd like to share it with other SW people who don't understand what PLCs are!
Can we create and add a 'PLC' tag to this series for easy searching?
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