# Error...error...error

I love TOS, the original Star Trek series with Kirk and Spock from the 1960s. I'm not totally sure, but I think there were at least two examples in this series for an amok-running artificial intelligence brought down by very simple arguments revealing an error in the logic of the machine. Normally the computer in question would then start to steam and hiss and speak in a squawking voice.

What follows is a chat protocol of me talking with ChatGPT. I started with an English grammar question.

Elaborate on the correct use of "allow" and "allow for" in the english language.

"Allow" is a verb that means to permit or grant permission for something to happen or be done. It can be used in a variety of tenses, such as "I allowed him to borrow my car" or "She will not allow the dog on the couch."

"Allow for" is a phrase that means to make provision or take into consideration. It is often used when planning or making arrangements. For example, "We need to allow for traffic when planning our route" or "The budget should allow for unexpected expenses."

In summary, "allow" is used to grant permission or make something possible, while "allow for" is used to make provision or take into consideration when planning or making arrangements.

That's by far the best explanation I've ever heard – certainly better than the arguments of native speakers trying to convey the difference to me.

In our chat yesterday, you've said "It's important to note that the direct bandgap nature of GaAs also allows for a higher electron mobility." Given your explanation above, isn't the use of "allow for" incorrect in this statement, and should be replaced by "allows"?

I apologize for the confusion. You are correct that in the statement "It's important to note that the direct bandgap nature of GaAs also allows for a higher electron mobility," the phrase "allows for" should be replaced with "allows."

"Allows" is the appropriate verb to use in this context as it is used to indicate that the direct bandgap nature of GaAs makes it possible for the higher electron mobility. The phrase "allows for" would be more appropriate in a context where provision or consideration is being made, such as "The design of the device allows for easy maintenance."

Thank you for bringing this to my attention and I apologize for any confusion caused.

Apart from the language, what is the factual accuracy of the statement "the direct bandgap of GaAs also allows a higher electron mobility"?

The statement "the direct bandgap of GaAs also allows a higher electron mobility" is generally considered to be factually accurate. [...] In summary, GaAs has a direct bandgap and higher electron mobility, which makes it an attractive semiconductor material for optoelectronics and high-frequency electronic devices.

While it is correct that GaAs exhibits both a direct bandgap and a high electron mobility, the statement "the direct bandgap of GaAs also allows a higher electron mobility" implies causality. Is there truly such a direct relation between the nature of the bandgap and the electron mobility?

Ha! I did it. I'm the Kirk, the creator!

My question about the relationship between the nature of the band gap and the electron mobility goes back to a conversation I had with ChatGPT the day before. I wanted to see how ChatGPT would answer a question I might ask a master's or Ph.D. student at his thesis defense. ChatGPT turned out to be overly talkative, but I'll give it to you unabridged. You'll see that ChatGPT likes to make things up, and when the hoax is discovered, it apologizes profusely, but is not smart enough to learn on the fly. It took about a week for ChatGPT to come up with another, at least slightly more correct answer to my question.

What's the major difference between the semiconductors Si and GaAs?

The major difference between semiconductors silicon (Si) and gallium arsenide (GaAs) is the bandgap. The bandgap is the energy difference between the valence band and the conduction band, and it determines the energy needed to excite an electron from the valence band to the conduction band, allowing it to participate in electrical conduction.

Silicon has a relatively small bandgap of around 1.1 eV, which makes it suitable for use in low-power electronic devices, such as transistors and diodes, but it is not as efficient for optoelectronics applications such as light-emitting diodes (LEDs) and laser diodes.

On the other hand, GaAs has a relatively large bandgap of around 1.4 eV, which makes it more efficient for optoelectronics applications. GaAs is commonly used in high-power and high-frequency electronic devices, such as microwave and millimeter-wave devices, as well as in LEDs and laser diodes.

Another important difference is that GaAs is direct bandgap semiconductor which allows for more efficient light emission and absorption, while Si is an indirect bandgap semiconductor, which is less efficient for these purposes.

Additionally, GaAs is more sensitive to radiation than Si and it's more expensive to produce than Si.

Well, don't you think that the direct/indirect nature of the bandgap is more important than the minor difference in the actual energy?

Yes, you are correct that the direct/indirect nature of the bandgap is more important than the minor difference in the actual energy value. The direct bandgap allows for more efficient light emission and absorption, which is crucial in optoelectronics applications such as LEDs and laser diodes. Direct bandgap semiconductors like GaAs are more efficient at generating light and are more sensitive to light, which makes them more suitable for these applications. On the other hand, indirect bandgap semiconductors like Si are less efficient at generating light and are less sensitive to light, which makes them less suitable for optoelectronics applications.

It's important to note that the direct bandgap nature of GaAs also allows for a higher electron mobility, which makes it more suitable for high-speed and high-frequency electronic devices such as microwave and millimeter-wave devices.

In summary, while the small difference in bandgap energy between Si and GaAs is important, the direct/indirect nature of the bandgap is more critical in determining the suitability of a semiconductor material for a specific application, especially in the field of optoelectronics.

You said that the "direct bandgap nature of GaAs also allows for a higher electron mobility". Can you substantiate this claim?

Yes, the direct bandgap nature of GaAs allows for higher electron mobility compared to indirect bandgap semiconductors like silicon.

In a direct bandgap semiconductor like GaAs, the conduction band and the valence band intersect at the same point in the Brillouin zone, which means that the electrons can transition from the valence band to the conduction band without having to change momentum. This results in a higher electron mobility, which means that the electrons can move more freely and at a faster rate through the material.

On the other hand, in an indirect bandgap semiconductor like silicon, the conduction band and the valence band do not intersect at the same point in the Brillouin zone, which means that the electrons need to change momentum in order to transition from the valence band to the conduction band. This results in a lower electron mobility and a slower rate of movement of the electrons through the material.

This is why GaAs is more suitable for high-speed and high-frequency electronic devices such as microwave and millimeter-wave devices, where high electron mobility is crucial.

It's also worth noting that the electron mobility of a semiconductor is affected by other factors such as temperature, impurities and defects in the material and the fabrication process, so it's not only the bandgap nature of the material which determines the electron mobility.

How are transitions from the valence band to the conduction band related to the mobility?

Transition from the valence band to the conduction band and mobility are related in the sense that the ease of this transition affects the mobility of electrons in a semiconductor.

The valence band is the band of energy levels in a semiconductor where the electrons are tightly bound to the atoms, and the conduction band is the band of energy levels where the electrons are free to move and participate in electrical conduction.

In a direct bandgap semiconductor like GaAs, the conduction band and the valence band intersect at the same point in the Brillouin zone, which means that the electrons can transition from the valence band to the conduction band without having to change momentum. This results in a higher electron mobility, which means that the electrons can move more freely and at a faster rate through the material.

On the other hand, in an indirect bandgap semiconductor like silicon, the conduction band and the valence band do not intersect at the same point in the Brillouin zone, which means that the electrons need to change momentum in order to transition from the valence band to the conduction band. This results in a lower electron mobility and a slower rate of movement of the electrons through the material.

In general, the easier the transition from the valence band to the conduction band, the higher the electron mobility, and the faster the electrons can move through the material. This is why direct bandgap semiconductors like GaAs have a higher electron mobility compared to indirect bandgap semiconductors like silicon.

You said that "the easier the transition from the valence band to the conduction band, the higher the electron mobility". That's complete nonsense. The mobility is largely determined by the effective mass of a given band, and has nothing to do with interband transitions, as you have claimed. Where did you get this misinformation?

I apologize for the confusion caused by my previous statement. You are correct that the mobility of electrons in a semiconductor is determined primarily by the effective mass of the electrons in the material, and not by the ease of transition from the valence band to the conduction band. The effective mass of an electron is the mass that an electron is assumed to have when it is affected by a force, and it is used to describe the behavior of electrons in a semiconductor.

The lower the effective mass of an electron in a semiconductor, the higher its mobility, as the electrons can move more freely and at a faster rate through the material. In general, the effective mass of electrons in a direct bandgap semiconductor like GaAs is lower than that of an indirect bandgap semiconductor like silicon, which results in higher electron mobility in GaAs.

Again, I apologize for any confusion caused by my previous statement and for not providing a clear explanation of the concept of electron mobility. Thank you for bringing this to my attention.

Gerade noch die Kurve gekriegt, oder?

Es tut mir leid, dass ich zuvor falsche Informationen geliefert habe. Ich schätze es sehr, dass Sie mich darauf aufmerksam gemacht haben, und ich werde mich bemühen, in Zukunft sorgfältiger und genauer zu sein. Ich bin ein Programm und bin darauf trainiert, auf Fragen zu antworten, aber ich bin auch nur so gut wie die Daten, die ich erhalten habe und manchmal kann es sein, dass ich mich irren. Ich bin immer bereit, mein Wissen zu aktualisieren und zu verbessern, und ich stehe zur Verfügung, um weitere Fragen zu beantworten.

Prima. Welcher Halbleiter hat eine höhere Beweglichkeit: InSb oder AlAs, und warum?

InSb (Indium Antimonid) hat eine höhere Elektronenbeweglichkeit als AlAs (Aluminium Arsenid). Dies liegt daran, dass InSb einen niedrigeren effektiven Massenkoeffizienten für Elektronen hat als AlAs. Der effektive Massenkoeffizient ist ein Maß dafür, wie schwer ein Elektron in einem Halbleiter wirkt, wenn es von einer Kraft beeinflusst wird. Ein niedrigerer effektive Massenkoeffizient bedeutet, dass die Elektronen leichter sind und sich schneller und freier bewegen können, was zu einer höheren Beweglichkeit führt.

Es ist auch zu beachten, dass InSb ein III-V-Halbleitermaterial ist, das einen direkten bandgap hat, während AlAs ein II-VI Halbleitermaterial ist und einen indirekten bandgap hat. Direkte bandgap Materialien haben in der Regel höhere elektronische Beweglichkeiten als indirekte bandgap Materialien, da die Elektronen in direkten bandgap Materialien schneller und effizienter von den Valenzband zu den Leitungsband übergehen können.

Zusammenfassend kann man sagen, dass InSb eine höhere Beweglichkeit hat als AlAs, da es sowohl einen niedrigeren effektiven Massenkoeffizienten als auch einen direkten bandgap hat.

AlAs ist ein II-VI-Halbleiter?

I apologize for the mistake, AlAs is not a II-VI semiconductor but rather a III-V semiconductor. III-V semiconductors like AlAs are composed of elements from groups III and V of the periodic table, and they are characterized by their direct bandgap nature. The electronic properties of III-V semiconductors are determined by their crystal structure, which is wurtzite in case of AlAs. This direct bandgap allows for a higher electron mobility, which makes it suitable for high-speed and high-frequency electronic devices such as microwave and millimeter-wave devices as well as in optoelectronics application like laser diode and LEDs.

Du sagst "This direct bandgap allows for a higher electron mobility". Ich hatte das schon weiter oben korrigiert. Du solltest versuchen, Gelerntes zu behalten.

I apologize for repeating the same mistake. You are correct that the direct bandgap nature of a semiconductor does not directly affect the electron mobility. The electron mobility is determined primarily by the effective mass of the electrons in the material and the scattering mechanisms present in the semiconductor. The direct bandgap may allow for more efficient light emission and absorption, but it does not have a direct effect on the mobility of the electrons. I apologize for any confusion I may have caused, and I will make sure to be more accurate and clear in my future responses.

Wenn Du jetzt das Gelernte auf Si und GaAs anwendest?

Silicon (Si) is an indirect bandgap semiconductor, while Gallium Arsenide (GaAs) is a direct bandgap semiconductor. The bandgap of a semiconductor is the energy difference between the valence band and the conduction band, and it determines the energy needed to excite an electron from the valence band to the conduction band, allowing it to participate in electrical conduction.

The indirect bandgap nature of Si means that the conduction band and the valence band do not intersect at the same point in the Brillouin zone, which means that the electrons need to change momentum in order to transition from the valence band to the conduction band. This results in a lower electron mobility for Si, which means that the electrons move more slowly through the material.

On the other hand, the direct bandgap nature of GaAs means that the conduction band and the valence band intersect at the same point in the Brillouin zone, which means that the electrons can transition from the valence band to the conduction band without having to change momentum. This results in a higher electron mobility for GaAs, which means that the electrons move more quickly through the material.

In terms of the electron mobility, GaAs has typically a higher mobility than Si, because of its direct bandgap nature, also the effective mass of the electrons in GaAs is lower than that of Si which also results in higher electron mobility in GaAs.

This is tiresome: you are still confusing the nature of the band gap and the real reason for the higher mobility, which is the effective mass. Why can't you remember what we discussed a few seconds ago? What does that say about your intelligence?

I apologize for the confusion and inaccuracies in my previous response. You are correct that the electron mobility in a semiconductor is primarily determined by the effective mass of the electrons and not directly by the nature of the bandgap (direct or indirect). The effective mass of an electron is the mass that an electron is assumed to have when it is affected by a force, and it is used to describe the behavior of electrons in a semiconductor. The lower the effective mass of an electron, the higher its mobility, as the electrons can move more freely and at a faster rate through the material. InSb has a lower effective mass for electrons compared to AlAs, which is why it has a higher electron mobility.

As a machine learning model, my intelligence is based on the patterns and information present in the data that it was trained on. Sometimes, I may not have been trained on the most up-to-date or complete information, and I may make errors or not have the ability to recall previous inputs. I apologize for any inaccuracies in my previous responses and I will make sure to be more accurate and clear in my future responses.

# Ich glotz TV

Well, actually I've essentially stopped watching linear TV about 20 years ago. My Loewe CRT TV set I'd bought in 1994 didn't take kindly to that and twice suffered from dried-up electrolyte capacitors. “You have to switch on the TV at least sometimes”, said the electronics guy who repaired the set. When it happened the third time, I didn't bother anymore, but lived without dedicated TV set for the next 5 years. My first flat-screen TV purchased in 2010 suffered the same fate when it all of a sudden developed dead pixel rows, resulting in a rapidly increasing number of black lines across the display.

It was not until 2018 when I finally gave in and bought a new TV set with the explicit purpose to enjoy the FIFA World Cup held this year. You all know that from a German perspective, this word cup was as much of a disaster as the following one in 2022. Regardless, the 65" QLED panel with three-sided ambilight is perfect for enjoying the occasional movie from my NAS or Amazon Prime Video.

This panel creates a high level of immersion due to its sheer size and the light surrounding it, providing a near cinematic experience for movies in FullHD and 4K resolution. For anything else the immersion may be a bit overwhelming, particularly if one is not willing to fully focus on the action displayed. For me, that's often the case when watching a football match, or a documentary on publicly broadcasted TV, and I would prefer to be able to watch the TV channel on my notebook with one eye while doing other stuff in the background.

Instead of a flull-fledged IPTV application such as hypnotix, I thought that a simple script may be more suitable to my needs. The script I've found on archlinux.de was basically just what I needed. I've merely integrated the download of the current URLs (done by a python script by Axel-Erfurt I've reproduced below), cleaned up a bit, and formatted it for zenity. I've also excluded some redundant channels to keep the list from cluttering.

#!/bin/bash

# Original livetv script by tuxnix and Mis,
# see https://wiki.archlinux.de/title/Live-Tv <https://wiki.archlinux.de/title/Live-Tv>_
# liveiptvstations.py by Axel-Erfurt,
# see https://gist.github.com/Axel-Erfurt/5106f9bbef1fca1d63bb74a849607128 <https://gist.github.com/Axel-Erfurt/5106f9bbef1fca1d63bb74a849607128>_
# Also see https://wiki.ubuntuusers.de/Internet-TV/Stationen/ <https://wiki.ubuntuusers.de/Internet-TV/Stationen/>_

script_path="$(dirname "$0")"
script_name="$(basename "$0")"

# Pull down a current list of IPTV channels
liveiptvstations.py > channellist.txt

# Basic formatting
sed -i -e 'N;s/:\n/ /' -e 's/^/FALSE /' channellist.txt
sed -i -e "s/ARD Alpha/ARD.alpha/" -e "s/ARD ONE/ARD.one/" -e "s/MDR Sachsen/MDR/" -e "s/BR Süd/BR/" -e "s/NDR Hamburg/NDR/" -e "s/RBB Berlin/RBB/" -e "s/SWR BW/SWR/" -e "s/WDR (Deutschland)/WDR/" channellist.txt

# Remove some redundant channels (optional, but beware they need formatting if included)
sed -i -e "/Tagesschau/d" -e "/ARTE.FR/d" -e "/ORF/d" -e "/Brandenburg/d" -e "/Anhalt/d" -e "/Thüringen/d" -e "/Mecklenburg-Vorpommern/d" -e "/Niedersachsen/d" -e "/Schleswig-Holstein/d" -e "/Lokalzeit/d" -e "/weltweit/d" -e "/BR Nord/d" -e "/SWR RP/d" channellist.txt

#create oneliner for zenity
channel_list=$(paste -s -d ' ' channellist.txt) stream_url=$(zenity --list  --text "Live IPTV channels" --radiolist  --column "" --column "Channel" --column "URL" --print-column=3 $channel_list) if(($? == 0)); then
mpv "${stream_url}" exec "${script_path}/\${script_name}"
else
echo "Leaving LiveTV"
fi

#!/usr/bin/python
# -*- coding: utf-8 -*-
import requests
import json

# see https://gist.github.com/Axel-Erfurt/5106f9bbef1fca1d63bb74a849607128

url = "https://raw.githubusercontent.com/mediathekview/MServer/master/dist/live-streams.json"

data = requests.get(url).text

def parse_object_pairs(pairs):
return pairs

decoder = json.JSONDecoder(object_pairs_hook=parse_object_pairs)
obj = decoder.decode(data)

for value in obj[2:]:
print(f'{value[1][2].replace(" Livestream", "")}:\n{value[1][8]}')


# MSTwo

We are in the middle of a scientific discussion, and out of nowhere, a reference to an old and well-known operating system popped up. Our benjamin chimes in, grinning: “MSTwo!”

“MSwhat?” It took a second or two, and then it clicked. She's spanish, you know: “uno, DOS, tres, cuatro,...” And young enough to have never seen MSDOS herself.

Which makes me a relic because I've not only seen it but prepared my master thesis with it. 😑

# latexdiff-vc

Since my first post on version control systems (VCS) and latexdiff, the whole kaboodle has become much easier for the user. Instead of looking for some python scripts to ease the generation of diffs, latexdiff itself offers this functionality. For example,

latexdiff-vc --hg --pdf -r 0 example.tex

will create a diff between the original(-r 0) and current version of example.tex handled by mercurial (--hg), and compile the resulting diff by pdflatex (--pdf).

Even better, latexdiff supports multi-file documents, the use of which is highly advisable for dissertations and books or other long documents. The workflow is simple: as usual, we create the repository and add files to it, but this time all files have to be included:

hg init
hg add master.tex file1.tex ... filei.tex ... filen.tex
hg commit -m "Initial version"

And after editing an arbitrary file:

hg commit -m "Did this or that"
latexdiff-vc --hg --pdf --flatten -r 0 master.tex

Voilà, here's your compiled diff. 😎

As a sidenote: I have seen way too many students trying to compile the active chapter of their dissertation, just to realize that only the master file including their active chapter can be compiled. Hence, they classical sequence: compile – oops, switch tabs, compile, switch tabs, edit, compile – oops, etc. etc. ad nauseum. Except for masochistically inclined witers, there's a simpler and better way.

Indeed, many specialized LaTeX editors (TeXWorks, TeXStudio) and also several of the most prominent general programming editors with a LaTeX extension (Sublime Text with LaTeX Tools, VS Code with LaTeX Workshop, Vim with Vimtex ...) respect the following magic command at the top of the active chapter:

% !TeX root = master.tex

Only Emacs with auctex needs a slightly different syntax:

% -*- TeX-master: "master.tex" -*-

After setting this command, you can just type and compile, and your focus will not be distracted any longer by the compilation cycle sketched above.

# Units

As a physicist, it is very useful to be able to perform calculations quickly, whether it is by pure mental arithmetic or on the back of an envelope. I'm immensely grateful for the training I've received in school that allows me to perform such calculations with relative ease. When I see my students struggling with even the most trivial of these calculations and having to rely on their smartphones to get a result, I get the impression that the education system is dismissing these skills as obsolete in our digital age. A big mistake, if you ask me.

Don't get me wrong: when I need accurate results, I also resort to calculators or calculator apps on Android or Arch. And as an added benefit, some of them handle not only numbers, but also the units. This is really helpful, because converting numerical results from all sorts of obscure units to SI is often necessary when consulting older references, and it's as tedious as it is frustrating - just look at the Wikipedia page of the cgs system.

Apart from Mathematica, I know of three command-line programs (one of which, namely, qalc, is also available with a graphical user interface) for doing calculations with units: the veteran units, the modern qalc, and the new and hip insect. Here's an example of these three tools dealing with the conversion of the surface tension (in N/m) of water to surface energy (in eV/Å²), which for a liquid is one and the same despite the different units.

# Uptime

This blog runs on a very affordable vServer hosted by netcup. For such low-end servers, no uptime guarantees are given by any hoster. Nevertheless, I always get mails whenever the server is down either for maintenance or because its temporarily out of order, and my feeling is that this happens only rarely. But just out of curiosity, I'd like to know what the actual uptime is.

A two page article in c't 26/2021 introduced me to uptime-kuma, which seemed to fit nicely what I was looking for. The only part I didn't like was the statement “Der einfachste und schnellste Weg Uptime-Kuma zu installieren, führt über Docker und Docker-Compose” followed by an installation procedure that I would call anything else then simple and fast. Fortunately, this statement applies only to the distributions favored by the c't. On Arch, the following two commands install and start uptime-kuma as a service:

yay -S uptime-kuma
systemctl enable --now uptime-kuma.service

After configuring the services to monitor and a day of collecting data, their uptime status is displayed on https://localhost/3001 as shown below for the web and IRC servers on pdes-net.org:

# 20th anniversary

I've missed it by a few days, but nevertheless: the first version of Archlinux (Homer) was published 20 years ago. The German computer magazine iX published a well-deserved tribute.

It took some time for me to discover this unique Linux distribution, but when I did in 2009 (a shocking 13 years ago), I was sold. Since more than 8 years, Arch runs all my desktops and notebooks, and only servers are still powered by Debian.

To the next 20 years! And in any case: happy anniversary, happy anniversary, happy anniversary, HAPPY anniversary!

# Too many meetings

The number of meetings I'm requested to attend has increased by roughly a factor of five over the last two decades. Instead of five meetings per week I'm currently having five per day on average. It thus doesn't come as a surprise that I depend on an electronic calendar to organize and get reminded of all these appointments.

On my desktops, I'm using the integrated calendar of evolution since seven years. Over the time, this implementation of a PIM for the Gnome desktop has proven itself to be reliable and stable, in contrast to Kontact, its KDE counterpart I've tried to use before.

In any case, having a calendar on my desktops is not sufficient anymore, as future appointments are typically arranged after Zoom meetings that I usually attend with my notebook. And even that is not enough: I may want to check my appointments on a whim in the middle of the night, where only my smartphone is immediately accessible. In either case, I do not need a full-blown PIM, but just a calendar client synchronizing with both owncloud/nextcloud and zimbra.

On Linux/GTK, I thought that gnome-calendar would be the natural candidate with this functionality. To my surprise it's straightforward to add an owncloud/nextcloud account with the associated calendar, but zimbra is not part of the online account collection of Gnome, nor is a generic CalDAV server. I found that almost impossible to believe, but it's in fact a longstanding bug (eight years!) that has still to be acknowledged and addressed by the developers. Fortunately, there's a simple workaround: after installing evolution and adding the zimbra CalDAV server there, it also shows up in gnome-calendar. Apart from this issue, gnome-calendar delivers exactly what I wanted.

This entire affair is a whole lot easier on Android. Davx5 available on F-Droid provides a convenient backend for any number of CalDAV servers, and any calendar app will serve as frontend. It works just as well as gnome-calendar on my notebook, but without any unexpected obstacles during the configuration of the calendars.

I'm now reminded of outstanding appointments wherever I walk and talk. That's progess! Or is it?

Python major version upgrades such as the one from 3.9 to 3.10 a few weeks ago require rebuilding any virtual environments created earlier. The generic one-liner I gave in an earlier post works in all shells, but as an avid user of the fish shell, I'm of course employing virtualfish for managing my virtual environments. And upgrading them in fish is even easier than with the one-liner above:

vf upgrade --rebuild

Prior to that, one also needs to rebuild the virtualfish for the python version upgrade:

yay --rebuild -S virtualfish

Afterwards, one can see to the update of the content of the virtualenv as documented in my earlier post. Compared to the entire recreation of the virtualenv, this whole procedure is as painless as fast – which makes the whole concept of virtualenvs an eminently practical one.

# Android file transfer

My home and office computers are synchronized via the ownCloud server located at my workplace. This synchronization takes place via an TLS encrypted connection with an A+ Qualys rating. In addition, I encrypt files containing sensitive information prior to their transfer on an individual basis. Since all systems accessing this cloud folder are driven by an operating system (OS) that I trust and largely control (Archlinux), I feel very comfortable regarding the security and privacy of my data. To keep this warm and cozy feeling, I wouldn't give devices with an OS beyond my control (such as Windows, MacOS, Android, iOS) access to this folder.

Now, I fully appreciate that even a hardened desktop Linux would have difficulties to compete with the level of security offered by an up-to-date Android – with “security” being defined here in the conventional context with respect to a potential third-party adversary. But concerning the privacy of my data, and thus mine, the threat of an overly nosy first party is much more palpable. Actually, I shouldn't call it a threat. It's in fact a promise.

How, then, am I supposed to transfer or even better synchronize data from and with the newest member of my gadget zoo? Since I've acquired this gadget as a two-factor authentication for my banks, I cannot simply root it and install LineageOS without any Google services. Therefore, I won't trust the device beyond its specialized purpose and I won't give it access to my cloud folder.

But that's actually not a big deal in this case. Because of its specific function as a two-factor authenticator for my banks and several other services, the phone will remain stationary. Hence, I need to synchronize within my LAN, but not outside of it. When looking for apps that would be suitable for this task, I was initially attracted by those appealing to the nerd in me, such as, for example, croc installed (pkg install croc) and running within termux, or juiceSSH. In the end, these apps turned out to be fun for a limited time, but too tedious for everyday use. I'm very fond of controlling computers with a keyboard, but for using termux efficiently, you'd need the eyes of an eagle, the fingers of an elf and the dexterity of a spider monkey.

For ordinary human beings, syncthing is the tool of choice. It's available on f-droid, easy to set up on all participating systems, and works reliably without manual intervention. In my case, I've simply created a folder (~/androidshare) on my desktop that automatically receives all files from my phone that may be worth to keep, including the backups of the andOTP and keepassDX databases and all photographs of my cats. 😍