Hello Linux community,

I need some help with shutting down my laptop when the battery reaches a low percentage.

I am using Debian 12 with the GNOME desktop. WARNING: Minimal installation with self selected packages.

What I want to achieve is, that the laptop just does a 'halt -p' or shuts itself down when the battery is below 20%.

What I did so far:

• Look into GNOME settings in the power settings area and I found nothing helpful
• I edited /etc/Upower/UPower.conf with my settings and changed the CriticalPowerAction to PowerOff, ensured the upower daemon is running via systemctl status and rebooted. The result was that I get a warning popup message in GNOME when the battery load reaches 21%, but it does not shutdown the laptop at 20% or under 20%, although I get another pop up announcing that the laptop would be shutdown
• I ensured laptop-mode-tools and gnome-power-manager settings are installed

Any help/pointers for further help would be highly appreciated.

The method of loci (MOL)/memory palaces are a widely known mnemonic devices and enable memory artists impressive tasks (like memorizing several decks of cards, memorizing numbers etc.). Further MOL is featured in pop culture e.g. Sherlock Holmes, Hannibal Lector etc...

There is, to the best of my knowledge quite some research, which shows that MOL is working/useful for improved retention, especially when combined with spaced repetition.

It seems I have never seem real world examples of long term memory palaces/method of loci applications. It always seems like a short term crutch for cards, numbers, speeches, grocery lists, phone numbers, vocabulary or for test/exam preparation. For example it seems that in language learning, the MOL is for encoding some vocabulary and visiting it regularly, until it is committed to long term memory.

All examples I find in books about the method of loci are again only about having one location, a route of 10-N stations, and never about building/using mnemonic devices to organize bigger amounts of knowledge.

Are there any examples of people using the method of loci/memory palaces to organize for example their professional knowledge? Or of polyglots having/keeping memory palaces for language learning? Is there any research about long term usage of the method of loci?

Can anyone recommend me books about the modern elite/modern nepotism and how it works?

I have experienced/observed modern nepotism several times in my life, to give you some examples:

• person founds a so called start up with money from person relatives, which boils down to paying other people to do all the work w/o anything resembling a business plan in the first place. Start up is a total failure, person gets job as a specialist for building startups via divine intervention.
• at several companies there is a level which people who do the work can reach, and above that level people from higher class get positions seemingly out of nowhere (unless they were childhood/study buddies of someone higher up) w/o any qualification/knowledge/experience to do this kind of work
• from a certain level on (at least in IT where we have more than enough money for it) everything is politics; when discussing technical problems/solutions at that level, the first question is always who is the sponsor behind the initiative and if this comes from the wrong party, the technical merits are of no interest at all
• a lot of positions even lower level in IT usually are distributed via nepotism/connections, I observed especially SCRUM masters and product owners are chosen for their family names/connections. (Two negative highlights: Product owner was literally boyfriend of company owner and another product owner was son of parent to which company wanted to sell their shit)
• lower on the list but still annoying and experienced several times: Son of friend of boss/manager/team lead gets internship in company although better candidates are there and often the nepotism sons would never have gotten an internship on their own merits, but end up with fancy internship from known company on their CV.

I understand that when you deal with a group of people politics are always relevant and inherent to groups.

My question is literately, how does this all work and why is this so extremely widespread?

Anyone can recommend some books about this social systems which give some insights?

Further, when I see what is mounted on money/time/energy because of this nepotism or the current favorite ideas of the elite, how comes no companies (that I know of) interrupt the market with a company slightly less dysfunctional.

Are there historical examples how elites/nepotism was overthrown w/o a bloody revolution?

I posted about ZRAM before, but because of my totally unscientific experiment, personal experience and the common question, which Linux to run on potatoes...

First, I tweaked ZRAM for my use-case(s) on my hardware, this settings might not be right for your use-cases or your hardware!

My hardware is a netbook with an Intel Celeron N4120 and 4G RAM (3.64G usable).

When I recently played around with ZRAM settings, it felt like the zstd algorithm made my netbook noticeable more sluggish. It never felt sluggish with lzo-rle or lz4.

In a totally unscientific way, I rebooted the computer several times (after a complete update of everything), executed my backup script several times, and measured the last 3 executions. (Didn't touch the netbook during the runs.) The bottleneck of the backup script should not be ZRAM, but it is some reproducible workload that I could execute and measure.

To my surprise, I could measure a performance difference for my backup scripts, lz4 was consistent fastest in real and sys time w/o tweaks to vm.page-cluster!

Changing the vm.page-cluster to 0 further enhanced the speed for lz4, but with this one toggle, all of a sudden zstd is as fast as lz4 in my benchmark and runs with a more consistent runtime.

Changing the vm.swapiness to 180 decreased the speed for lz4, to my surprise.

Obviously the benchmarks are not 100% clean, although the trend for my workload was clearly in favor of lz4/zstd.

To the best of my knowledge, I ended up with nearly the same tweaks that Google makes for ChromeOS:

• zstd as algorithm (I think ChromeOS uses lzo-rle)

• 2*ram as ram-size

• vm.page-cluster = 0

• Install/enable systemd-oomd

vm.page-cluster = 0 seems like a no-brainer when using ZRAM, on my netbook it is literally the switch for 'fast' mode.

In summary: ZRAM makes my netbook totally usable for everyday tasks, and with tweaking the above settings I run Gnome 3, VS Code and Firefox/Evolution w/o trouble. (Of course, Xfce4 on the same machine is still noticeable more performant.)

I wonder if we should recommend to people asking for a lightweight distribution for potatoes to check/tweak their ZRAM settings by default.

Anyway, I would be interested in experiences from other people:

1. Any other tweaks on my ZRAM or sysctl for potatoes which made a measurable difference for you?
2. Any other tips to improve quality of life on potatoe machines? (Besides switching to KDE, LXDE, Xfce, etc. ;-))
3. Any idea why vm.swapiness didn't improve my measurements? To my understanding it should basically have cached more of my files in ZRAM, making the backup run faster. It even slowed the backup down, which I don't understand.

Edit:

• zstd beats lz4 on my machine for my benchmark when vm.page-cluster=0!

... I mean, WTF. Mozilla, you had one job ...

Edit:

Just to add a few remarks from the discussions below:

1. As long as Firefox is sponsored by 'we are not a monopoly' Google, they can provide good things for users. Once advertisement becomes a real revenue stream for Mozilla, the Enshittification will start.
2. For me it is crossing the line when your browser is spying on you and if 'we' accept it, Mozilla will walk down this path.
3. This will only be an additional data point for companies spying on you, it will replace none of the existing methodologies. Learn about fingerprinting for example
4. Mozilla needs to make money/find a business model, agreed. Selling you out to advertisement companies cannot be it.
5. This is a very transparent attempt of Mozilla to be the man in the middle selling ads, despite the story they tell. At that point I can just use Chrome, Edge or Safari, at least Google has expertise and the money to protect my data and sadly Chrome is the most compatible browser (no fault of Mozilla/Firefox of course).
6. Mozilla massively acts against the interests of their little remaining user base, which is another dumb move made by a leadership team earning millions while kicking out developers and makes me wonder what will be next.

Interesting workflow.

Of course the fact that Nate uses Thunderbird instead of KMail explains a lot. One day I hope KMail/Akonadi get the attention/work they need to become viable options.

Interesting workflow.

Of course the fact that Nate uses Thunderbird instead of KMail explains a lot. One day I hope KMail/Akonadi get the attention/work they need to become viable options.

Interesting times ahead! I am really looking forward to the Leap Micro release and hope it advances the state of the art. :-)

Solved: The files are encrypted, see stackoverflow

Hope it is ok to ask technical questions in this channel!

I found a folder of files on one of my back drives which was copied from a very old Sony Ericson cell phone or a SAMSUNG Galaxy S2.

The folder is called DCIM and in a sub folder called Camera there are files with a .jpg extension.

This files are not standard JPG files. They start with the following header:

0000000 0000 0000 3900 c0d8 ac5f d196 2d63 2421
0000010 0003 0200 0000 0010 0200 2d8c 0904 0103
0000020 0000 0000 0000 0000 e960 2861 7025 ba0e
0000030 2424 dcfa 3e3b ee64 0800 c87b a43a a90d
0000040 7287 b815 7ca4 9680 ed65 6216 5f08 4f43
0000050 534e 4c4f 0045 0000 9000 b3e9 1333 92b9
0000060 0002 0000 0000 0000 0000 0000 0000 0000
0000070 0000 0000 0000 0000 0000 0000 0000 0000

And the last bytes look like this:

039fea0 60ff 01fa 6b1e 8ef5 7c6f e69f fd9e 1589
039fef0 2199 dbd9 13fe 337d 2e9f d862 e252 080d

(obtained via hexdump -n 1024 filename.jpg).

The file command just returns 'data'.

The jpgrecovery command simply does not process this files.

The strings command finds an embedded string "_CONSOLE" !

If I open the file in a file viewer (shotwell, GIMP, Firefox, Google Chrome), I get the error that the file starts with 0 0, which is correct, as seen in the above hexdump.

Using identify from the imagemagick package results in:

20140207_142030.jpg JPG 0x0 16-bit sRGB 3.625MiB 0.000u 0:00.002
identify-im6.q16: Not a JPEG file: starts with 0x00 0x00 `20140207_142030.jpg' @ error/jpeg.c/JPEGErrorHandler/338.

All this commands were executed on Debian 12.

I have hundreds of files with this JPG extension and for each file the header is starting with 0 0 in this folder, so I assume the problem is not corruption of one file.

My questions:

1. What kind of file format is this?
2. How can I convert the files to JPGs?

Edit: Added the output of some suggested data/commands to questions Edit: Mark as solved, thanks to @hades@hades@lemm.ee .

Thanks a lot to everyone helping to figure this out/pointing me in the right direction! <3

Solution: Indeed it was EncFs file level encryption.

Thanks a lot for everyone helping!

Original post below:

Hope it is ok to ask technical questions in this channel!

I found a folder of files on one of my back drives which was copied from a very old cell phone or a SAMSUNG Galaxy S2.

The folder is called DCIM and in a sub folder called Camera there are files with a .jpg extension.

This files are not standard JPG files. They start with the following header:

0000000 0000 0000 3900 c0d8 ac5f d196 2d63 2421
0000010 0003 0200 0000 0010 0200 2d8c 0904 0103
0000020 0000 0000 0000 0000 e960 2861 7025 ba0e
0000030 2424 dcfa 3e3b ee64 0800 c87b a43a a90d
0000040 7287 b815 7ca4 9680 ed65 6216 5f08 4f43
0000050 534e 4c4f 0045 0000 9000 b3e9 1333 92b9
0000060 0002 0000 0000 0000 0000 0000 0000 0000
0000070 0000 0000 0000 0000 0000 0000 0000 0000

(obtained via hexdump -n 1024 filename.jpg).

The file command just returns 'data'. The jpgrecovery command simply does not process this files. If I open the file in a file viewer (shotwell), I get the error that the file starts with 0 0, which is correct, as seen in the above hexdump.

All this commands were executed on Debian 12.

I have hundreds of files with this JPG extension and for each file the header isstarting with 0 0 in this folder, so I assume the problem is not corruption of one file.

My questions:

1. What kind of file format is this?
2. How can I convert the files to JPGs?

For years now, I do not buy/create assemble a new computer, because I am totally overwhelmed by the options available to me.

If we agree there is 'The Paradox of Choice', it seems to make sense to have a much more limited choice between CPU models from a consumer point of view. For example, have for each year an entry, business and a pro model, add extreme for gamer and have each of these models have a version with a beefy integrated CPU.

But it seems also a good idea for the manufacturers: They have to design, test and build each of their models, create advertisement etc., like configuring their assembly lines alone costs money. Further, compilers have to generate code for a specific architecture, which means that all my software I didn't compile myself ends up using an instruction set of the lowest common CPU, not utilizing whatever I bought fully.

Apple (not a fan ;-)) shows IMHO how it is done with their Apple Silicon: Basically even I understand which CPU choice would be the right one for me. The Steam Deck is IMHO another success story: As reference hardware I know easily if I can play a game, and it is easy to know if my hardware is faster than a Steam Deck. Compare that to games with hardware requirements like 'AMD TI 5800 8GB RAM' (made up model) which makes my life miserable.

What I am looking for is fact based knowledge:

• Why does it make (commercial) sense for AMD/Intel to create so many models?
• What are their incentives?
• What would happen, if they would reduce the amount of different CPUs they offer? (Is there historical knowledge?)

What are CPU designs which are not fetch/store but operate directly on RAM?

I only know about the design of the Nintendo Entertainment System (NES), where the CPU does not have registers (AFAIK) and operates directly on RAM, with fast access to low addresses in the RAM.

What CPUs/Systems do you know, which also do not do fetch/store for their operands? Which systems are out there? Why do CPUs like RISC/Arm/AMD64 use fetch/store, what are the tradeoffs? Are there different architectures for CPUs working on operands outside of fetch/store, DMA and stack machines?