Hacker Public Radio

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This series is dedicated to exploring little-known—and occasionally useful—trinkets lurking in the dusty corners of UNIX-like operating systems.

As the zeroth entry of this series, we'll have a little introduction to what it is supposed to be about and why you might want to listen. So that you don't leave without getting at least one piece of useful information, it will end with a little curio that you might find helpful someday.

Back in 2010, I was the editor of the newsletter, titled The Open Pitt, for the Western Pennsylvania Linux Users Group in Pittsburgh. We distributed it as a two-page PDF, so had to have enough material to fill each issue. Because we were having some trouble getting contributions, I started writing columns in a series called "UNIX Curio" to occupy the empty space. They were inspired in large part by examples I had seen of people re-inventing ways to do things when utilities for the same purpose had already existed for a long time.

The obvious question is: just what is a UNIX Curio? Let's start with the first word, UNIX. While a lot of people write it "Unix" instead, I have chosen to put it in all capitals because that is the way The Open Group, which controls the trademark and the certification process to use it, spells the word
1
. The history of UNIX is complex (search online for more details
2
)—the short version is that many variants emerged, often introducing incompatibilities. Even within AT&T/Bell Laboratories, two major branches came out. The Research UNIX lineage, which includes Seventh Edition (sometimes called Version 7), was often used in universities and government while System III and its more popular successor System V were clearly intended as commercial products
3
. The University of California's BSD was also very influential. My intention is to talk about things that are relatively common; ideally, they would be present on a large majority of systems so you can actually
use
them.

Luckily, there were people who recognized the value in compatibility, so in the mid-1980s they initiated the development of the POSIX standards
4
. Publication of these not only caused commercial UNIX versions to aim for conformance—it gave Free Software implementations of utilities and operating systems a stable base to shoot for rather than having to chase multiple moving targets. As a result, today's GNU/Linux, FreeBSD, NetBSD, and OpenBSD systems generally behave as specified in POSIX, even if they haven't officially earned the UNIX or POSIX labels, so I treat them as part of the UNIX world.

Moving on to the second word, "curio," it just means "an object of curiosity, often one considered novel, rare, or bizarre." There are many well-used utilities in the UNIX world, but people forget about others because they are only useful in specific circumstances. And when those circumstances arise, these obscure ones don't always get remembered. One purpose of this series is to point out some of them and describe where they can be appropriately put to use.

With the flexible tools available on UNIX systems and the ability to string them together, it shouldn't be surprising that people come up with new ways to accomplish a task. I don't want to claim that these curios are always the
best
way to do something, just that it can be helpful to know they exist and see the way someone else solved the problem. Also, if you're using an unfamiliar system, sometimes programs you are accustomed to employing might not be installed so it's good to know about options that are widely available.

So why am I the person to talk about this subject? I am
not
a UNIX graybeard with decades of professional computing experience. If I did grow a beard, it would only be partially gray, and my working life has been spent in the engineering world mainly around safety equipment. Sadly, there I have been forced to use Windows almost exclusively. However, in my academic and personal pursuits, I have been involved with using UNIX and Linux for more than 30 years, so I do have a bit of a historical perspective. For some reason, when I encounter an unusual or obscure tool, I want to learn more about it, especially so if I find it to be useful in some way. After gaining that information, I might as well share it with you. In addition, I have been involved with Toastmasters International, a public speaking organization, for about 15 years so I have experience in presenting things orally. I was inspired to turn this article series into podcasts by murph
5
, who delivered a presentation at the 2025 OLF Conference describing how and why to contribute to Hacker Public Radio
6
.

The show notes for curios 1 through 3 will consist of the articles as they were originally written (though with references added). Because some examples, especially code, can be difficult to understand when they are read out loud, the podcasts will sometimes present the information in a different way. Show notes for this curio 0 and for curios 4 and later will be written with the podcast format in mind, so they will more closely match what I say.

Let's end with an actual curio to kick off the series. Have you ever needed a quick reminder about whether the file you're looking for can be found under the /usr or /var directories? On many UNIX systems,
man hier
will give you an overview of how the file hierarchy is organized. This manual page is not a standard, but was present in Seventh Edition UNIX
7
and many descendents, direct and indirect, including every Linux distribution I have ever used. There
are
attempts to standardize the layout; in the Linux world, the Filesystem Hierarchy Standard (FHS)
8
, now hosted by Freedesktop.org
9
, intends to set a path to be followed. It should be noted that systemd has its own idea of how things should be laid out based on the FHS; if it is in use, try
man file-hierarchy
instead as it will likely be a more accurate description.

I hope this gives you a good idea of what to expect in future episodes. The first one will be about shell archives, so keep an eye on Hacker Public Radio's schedule for it to appear.

References:

The Open Group Trademarks
https://www.opengroup.org/trademarks

History of Unix
https://en.wikipedia.org/wiki/History_of_Unix

The Unix Tutorial, Part 3
https://archive.org/details/byte-magazine-1983-10/page/n133/mode/2up

POSIX Impact
https://sites.google.com/site/jimisaak/posix-impact

Correspondent: murph
https://hackerpublicradio.org/correspondents/0444.html

OLF Conference - December 6th, 2025
https://www.youtube.com/watch?v=hyEunLtqbrA&t=25882

File system hierarchy
https://man.cat-v.org/unix_7th/7/hier

Finding a successor to the FHS
https://lwn.net/Articles/1032947/

Freedesktop.org now hosts the Filesystem Hierarchy Standard
https://lwn.net/Articles/1045405/

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Thorium Reactors

01 Introduction

In this episode we will describe the use of thorium in nuclear power, including what thorium is, how it differs from uranium, and what sort of reactors can use it.

03 What is thorium

05 How thorium differs from uranium

07 Sources of Thorium

09 Why there is interest in using thorium as a fuel

10 Abundance of Thorium

11 Some Countries Have a Lot of It

12 Thorium Breeder Reactors are Simpler than Uranium Breeder Reactors

14 Supposed Lower Nuclear Weapons Potential

16 What is Thorium Breeding

20 Breeding Ratio

21 What sorts of reactors can use thorium

22 PHWRs - Heavy Water Reactors (Including CANDU)

24 HTR - High Temperature Gas Cooled Reactors

26 MSR - Molten Salt Reactors

29 Light Water Reactors (PWR, BWR)

31 Fast Neutron Reactors

32 The Challenges Facing Thorium Fuelled Reactors

37 Thorium in India - An Example Use Case

39 Why is India Pursuing Using Thorium?

40 How a Thorium Fuel Cycle Would Work in India

43 Current Status

46 Conclusion

Thorium is an abundant material that is seen as an alternative to uranium in nuclear power.

Experimental thorium power reactors date back to at least the 1960s.

No new reactor technology is required to use thorium.

Existing well proven reactor designs which have been in use for decades can use thorium as fuel.

The common light water reactor designs that popular in some countries however are not well suited to using thorium.

Initial interest in thorium was mainly driven by a perception that uranium would be in short supply in future, and slow neutron thorium reactors were cheaper and simpler than fast neutron uranium reactors.

However, huge new high grade supplies of uranium were found in a number of countries, causing uranium prices to fall and reducing interest in finding alternatives.

While some R&D continues on thorium fuel in a number of countries, the mainstream of development continues to be on uranium based fuel.

Some countries with abundant thorium reserves though maintain a major interest in thorium, with India being the prime example.

In the next episode we will describe small modular reactors.

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These are the commands mentioned in the You may need to use
"sudo" to run these commands depending on how your system is
configured.

strace uptime

strace ls 2>&1 | grep open

strace -e openat ls /

strace ls /does/not/exist

strace -o ls-trace.log ls

strace -ff -o pid12345-trace.log -p 12345



HISTORY


The original strace was written by Paul Kranenburg for SunOS and
was inspired by its trace utility. The SunOS version of strace was
ported to Linux and enhanced by Branko Lankester,
who also wrote the Linux kernel support. Even though Paul released
strace 2.5 in 1992, Branko's work was based on Paul's strace 1.5
release from 1991.



In 1993, Rick Sladkey took on the project. He merged strace 2.5
for SunOS with the second release of strace for Linux, added many
features from SVR4's truss(1), and produced a ver‐
sion of strace that worked on both platforms. In 1994 Rick ported
strace to SVR4 and Solaris and wrote the automatic configuration
support. In 1995 he ported strace to Irix (and
became tired of writing about himself in the third person).



Beginning with 1996, strace was maintained by Wichert Akkerman.
During his tenure, strace development migrated to CVS; ports to
FreeBSD and many architectures on Linux (including
ARM, IA-64, MIPS, PA-RISC, PowerPC, s390, SPARC) were introduced.



In 2002, responsibility for strace maintenance was transferred to
Roland McGrath. Since then, strace gained support for several new
Linux architectures (AMD64, s390x, SuperH), bi-
architecture support for some of them, and received numerous
additions and improvements in system calls decoders on Linux;
strace development migrated to Git during that period.



Since 2009, strace has been actively maintained by Dmitry Levin.
During this period, strace has gained support for the AArch64,
ARC, AVR32, Blackfin, C-SKY, LoongArch, Meta, Nios
II, OpenRISC 1000, RISC-V, Tile/TileGx, and Xtensa architectures.
In 2012, unmaintained and apparently broken support for non-Linux
operating systems was removed. Also, in 2012
strace gained support for path tracing and file descriptor path
decoding. In 2014, support for stack trace printing was added. In
2016, system call tampering was implemented.



For the additional information, please refer to the NEWS file and
strace repository commit log.


Links


https://strace.io

https://en.wikipedia.org/wiki/Strace

https://www.man7.org/linux/man-pages/man1/strace.1.html

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We start with
Orwellian depictions of the future
read about in the 1950/60s. Working in the 1970s at companies such as
British Telecom
and the L
urgie
. We hear about
telex
,
mainframes
with
magnetic tape
,
type-writers
, and the upskilling of the workforce by the
labour-exchange
. How did a cold and lack of a home telephone lead to businessmen arriving in a foreign land sans camels? Why were
filing cabinets
replaced by
databases
(or were they)? We hear about gaming from a home made version of
Pong
all the way to
Alone in the Dark
. Then modern times: we hear about some favourite
youtube
streams and discover that living in the 2020s is (just about) possible without a
smartphone
.

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In our next look at the game mechanics for Civilization V we examine several related topics: Diplomacy, Spies, and Religious Pressure. They are all ways to interact with other players without the force of arms being involved. And we will discuss the Diplomatic Victory, which is a new victory type added in Civilization V and can be fun to play.

Playing Civilization V, Part 8 - Diplomacy

Other Players

With other players you have a relationship based on their approach to you. They are:

Neutral – This is not Friendly nor is it Hostile. Trades you make with them will be fair from their point of view

Friendly – They like you, and will accept requests from you more often. Trades will be slightly in your favor from their point of view.

Afraid – This only happens if you have a a very substantial advantage in strength, so this is rare. They will readily accept requests from you, and trades will be in your favor

Guarded – They are suspicious and defensive, and will be more likely to be unfriendly. Trades will be harder to achieve, and favor them rather than you.

Deceptive – They will pretend to be friendly, but they are plotting against you. They may bribe other players to declare war on you. They will not accept requests for help, and trades will be hard to achieve.

Hostile – They hate you, and are completely open about it. Trade deals, if you can get them, will be heavily against you.

War – This means they have decided to go to war with you. But they need the right conditions, so they may pretend to be Friendly, Neutral, Guarded, or Hostile while they wait for those conditions to mature.

These are not set in stone, as you can modify how the other player feels towards you by your actions. If you have friends in common that will improve your relationship, or if you have enemies in common. Agreeing to their requests will also improve things. But if you cannot agree, just say so. The worst negative modifier is when you agree to do something, and then do the opposite. Saying no is also negative, but not as bad. Finally, remember that negatives will erode over time if they are not reinforced. If you want a very detailed look at the mechanics and details of this, check out https://civ-5-cbp.fandom.com/wiki/Detailed_Guide_to_Diplomacy.

City-States

City-States are also important diplomatic partners. We’ll cover all of the benefits in a different section, but here I want to focus on how they enable the Diplomatic Victory. At a certain point the United Nations will be born out of the World Congress, and when this happens a Diplomatic Victory is possible. This will occur when any player reaches the Information Era, or whenever half of the players have reached the Atomic Era. Diplomatic Victory requires that you get the votes of a certain number of delegates to the United Nations. Each player gets delegates based on their population, and there are also some additional delegates you can earn, such as through building the World Wonder Forbidden Palace which gives you two additional delegates. Anyone planning for a Diplomatic Victory should consider building this Wonder as mandatory.

But each City-State gets one delegate, and if you are allied with them their delegate is yours. The mechanics of City-State relationships is that they love gifts, and cash is always the best. So anyone planning a Diplomatic Victory would be well-advised to focus on building a large Treasury. You will know when a World Leader vote is coming up in the United Nations, and can make cash drops on any City-States that are not already allied with you before the vote. But watch out that another player doesn’t do the same thing after you and snipe away some of your allies. Also, you can place your spies in City-States to rig elections, and that is another way to get them to ally with you.

Spies and Espionage

Spies are simply awarded to you whenever any player enters the Renaissance Era. After that you receive another spy each time to advance to another Era. So you can in general have as many as 5 Spies, but if you build the National Intelligence Agency you get one more. This is a National Wonder, and should be a mandatory build if you are going for a Diplomacy victory. And England starts with 1 extra Spy, so if you play as England you could get as many as 7 Spies.

Spies can be used for offense or defense. If you station one of your spies in one of your cities it can operate as a counter-spy, and may thwart or even kill an enemy spy. If you are well ahead in technology, that might be a good use, since other players will be trying to steal your tech. But if you are behind, you might want to use your spies to steal tech from other players. You may be successful in this, but the theft does not go unnoticed, and other player may use one of his spies to counter your operation. If you spy is killed, you will get another one in 3-5 turns, but if your spy was a high-rank spy with promotions, that is a serious loss, so you may want to move that spy elsewhere for a while.

Diplomats

When you assign a spy to the capital of another player you can designate them as a Diplomat. They will take a few turns (depends on game speed, but around 6 turns on normal speeds) to get set up. This is called “Making Introductions”, but the point is that if you need an effective diplomat, don’t wait until the last minute. Diplomats can be useful in several ways. Early on, they allow you to trade votes in the World Congress. And they will bring you intelligence about intrigues, and you can then share that with other players. And it can also give you a view of the other player’s City Screen. Once you have researched Globalization your Diplomats can help with a Diplomatic Victory because each one counts as one additional vote in the United Nations for World Leader.

You can change a spy into a Diplomat and vice versa just by moving the Spy/Diplomat from its current location to another location, which will trigger the ability to change the job assignment. This means that when you first get Spies, and they cannot yet be used to get additional Delegate votes as Diplomats, you can assign them to City-States, where they can help you get alliances. Then as you start to research Globalization, move them to the capitals of other players and turn them into Diplomats. This of course assumes you want to win a Diplomatic victory. If instead you are going for a Science victory and are ahead in Science, it is probably best to station them in your own cities to do counter-intelligence work. If you are ahead in Science, other players will be trying to steal tech from you.

Religious Pressure

If you have researched all of the Piety Social Policy Tree, you will have option to choose a Reformation Belief to add to your religion. One of these, Underground Sect, allows your spies to exert religious pressure against the city they have been sent to. However, this effect is fairly small. If there is not a Follower of your religion in the city, it seems to do nothing. But in combination it can flip cities to your religion. Start by sending in a Missionary to spread your religion, then your spy can add to that. And you should also combine that with a trade route to add additional religious pressure. And by gradually moving your spies, missionaries, and trade routes from city to city, you can make your religion dominant in a region.

Diplomatic Victory

This can be a fun way to win, and I have done it. If you want to get a leg up, start with a Civ that gives you advantages, such as Greece or Venice (although my last diplomatic Victory was achieved with Ethiopia, which is generally regarded as a military/domination Civ. You can win any victory type with any civ, and it can be fun to “play against type”). Greece gets an advantage from relations with City-States, which are key to a Diplomatic Victory because each one gets a vote for World Leader. And Venice is interesting because you cannot build settlers. But you can use cash to puppet City-States, and you can purchase units in puppeted City-States as well. Cash is king in the Venice strategy, and you will want to get as many Trade Routes as possible. The first two should send Food to Venice to help boost your population. Since you will only ever have one city as Venice you will want to max it out. All trade routes after that should focus on cash. Use your cash to purchase or upgrade military units, and employ a defensive strategy. You want enough military to deter any aggression against you, but you should avoid making any hostile moves against others if possible. Remember, this is a strategy for a Diplomatic Victory. If you want to go to war, don’t choose Venice. Instead choose one of the Domination Civs, like the Zulus or the Mongols.

Links:

https://civ-5-cbp.fandom.com/wiki/Detailed_Guide_to_Diplomacy

https://www.palain.com/gaming/civilization-v/playing-civilization-v-part-8/

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