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My struggle from a UNIX background in the modern "cloud" world
  • Since when do Unix tools output 3,000 word long usage info? Even GNU tools don’t even come close…

    [zlatko@dilj ~/Projects/galactic-bloodshed]$ man grep | wc -w
    4297
    [zlatko@dilj ~/Projects/galactic-bloodshed]$ man man | wc -w
    4697
    [zlatko@dilj ~/Projects/galactic-bloodshed]$ 
    
  • D or d come on
  • No problem!

    As an aside, I see we're bringing the strangers thing over from Reddit. I hope more of the fun and funny stuff gets over, I miss some of the light shitposting.

  • D or d come on
  • XDG specifies the capital names, but to be nitpickingly technically precise, linux systems don't do this. It mostly is done by the distribution maintainers, and the XDG specs. A base system does not usually have a notion of anything beyond your $HOME.

    Try adding a user: sudo adduser basicuser. If you ls -al ~basicuser you will see it's almost empty, just the .bashrc (or in my fedora, there's some .mozilla crap in /etc/skel that also gets bootstrapped).

  • D or d come on
  • For bash, this is enough:

    # Bash TAB-completition enhancements
    # Case-insensitive
    bind "set completion-ignore-case on"
    # Treat - and _ as equivalent in tab-compl
    bind "set completion-map-case on"
    # Expand options on the _first_ TAB press.
    bind "set show-all-if-ambiguous on"
    

    If you also add e.g.CDPATH=~/Documents, it will also always autocomplete from your Documents no matter which directory you're on.

  • 0.30000000000000004
  • Sure -> I'm not smart enough to explain it like you're five, but maybe 12 or so would work?


    The problem

    The problem here is that you're not adding 1 + 2, or 0.1 + 0.2. You're converting those to binary (because computers talk binary), then you're adding binary numbers, and converting the result back. And the error happens at this conversion step. Let's take it slow, one thing at a time.


    decimal vs binary

    See, if you are looking at decimal numbers, it's kinda like this:

    357 => 7 * 1 + 5 * 10 + 3 * 100. That sequence, from right to left, would be 1, 10, 100, ... as you go from right to left, you keep multiplying that by 10.

    Binary is similar, except it's not 1, 10, 100, 1000 but rather 1, 2, 4, 8, 16 -> multiply by 2 instead of 10. So for example:

    00101101 => right to left => 1 * 1 + 0 * 2 + 1 * 4 + 1 * 8 + 0 * 16 + 1 * 32 + 0 * 64 + 0 * 128 => 45

    The numbers 0, 1, 2, 3..9 we call digits (since we can represent each of them with one digit). And the binary "numbers" 0 and 1 we call bits.

    You can look up more at simple wikipedia links above probably.


    bits and bytes

    We usually "align" these so that we fill with zeroes on the left until some sane width, which we don't do in decimal.

    132 is 132, right? But what if someone told you to write number 132 with 5 digits? We can just add zeroes. So call, "padding".

    00132 - > it's the same as 132.

    In computers, we often "align" things to 8 bits - or 8 places. Let's say you have 5 - > 1001 in binary. To align it to 8 bits, we would add zeroes on the left, and write:

    00001001 -> 1001 -> decimal 5.

    Instead of, say, 100110, you would padd it to 8 bits, you can add two zeroes to left: 00100110.

    Think of it as a thousands separator - we would not write down a million dollars like this: $1000000. We would more frequently write it down like this: $1,000,000, right? (Europe and America do things differently with thousands- and fractions- separators, so 1,000.00 vs 1.000,00. Don't ask me why.)

    So we group groups of three numbers usually, to have it easier to read large numbers.

    E.g. 8487173209478 is hard to read, but 8 487 173 209 478 is simpler to see, it's eight and a half trillion, right?

    With binary, we group things into 8 bits - we call that "byte". So we would often write this:

    01000101010001001010101010001101

    like this:

    01000101 01000100 10101010 10001101

    I will try to be using either 4 or 8 bits from now on, for binary.


    which system are we in?

    As a tangential side note, we sometimes add "b" or "d" in front of numbers, that way we know if it's decimal or binary. E.g. is 100 binary or decimal?

    b100 vs d100 makes it easier. Although, we almost never use the d, but we do mark other systems that we use: b for binary, o for octal (system with 8 digits), h for hexadecimal (16 digits).

    Anyway.


    Conversion

    To convert numbers to binary, we'd take chunks out of it, write down the bit. Example:

    13 -> ?

    What we want to do is take chunks out of that 13 that we can write down in binary until nothing's left.

    We go from the biggest binary value and substract it, then go to next and next until we get that 13 down to zero. Binary values are 1, 2, 4, 8, 16, 32, ... (and we write them down as b0001, b0010, b0100, b1000, .... with more zeroes on the left.)

    • the biggest of those that fit into 13 seems to be 8, or 1000. So let's start there. Our binary numbers so far: 1000 And we have 13 - 8 = 5 left to deal with.

    • The biggest binary to fit into 5 is 4 (b0100). Our binary so far: b1000 + b0100 And our decimal leftover: 5 - 4 = 1.

    • The biggest binary to fit into 1 is 1 (b0001). So binary: b1000 + b0100 + b0001 And decimal: 1 - 1 = 0.

    So in the endl, we have to add these binary numbers:

    ` 1000 0100 +0001

    b1101 `

    So decimal 13 we write as 1101 in binary.


    Fractions

    So far, so good, right? Let's go to fractions now. It's very similar, but we split parts before and after the dot.

    E.g. 43.976 =>

    • the part before the dot (whole numbers part) -> 1 * 3 + 10 * 4 = > 13
    • the part after it (fractional part) -> 0.1 * 9 + 0.01 * 7 + 0.001 * 6
      Or, we could write it as: 9 / 10 + 7 / 100 + 6 / 1000.

    Just note that we started already with 10 on the fractional part, not with 1 (so it's 1/10, 1/100, 1/1000...)

    The decimal part is similar, except instead of multiplying by 10, you divide by 10. It would be similar with binary: 1/2, 1/4, 1/8. Let's try something:

    b0101.0110 ->

    • whole number part: 1 * 1 + 2 * 0 + 4 * 1 + 8 * 0 (5)
    • fractional part -> 0 / 2 + 1 / 4 + 1 / 8 + 0 / 16 -> 0.375.

    So b0101.0110 (in binary) would be 5.375 in decimal.


    Converting with fractions

    Now, let's convert 2.5 into binary, shall we?

    First we take the whole part: 2. The biggest binary that fits is 2 (b0010). Now the fractional part, 0.5. What's the biggest fraction we can write down? What are all of them?

    If you remember, it's 1/2, 1/4, 1/8, 1/16... or in other words, 0.5, 0.25, 0.125, 0.0625...

    So 0.5 would be binary 1/2, or b0.1000

    And finally, 2.5 in decimal => b0010.1000

    Let's try another one:

    13.625

    • Whole number part is 13 -> we already have it above, it's b1101.
    • Fractional part: 0.625. The bigest fraction that fits is 0.5, or 1/2, or b0.1. We have then 0.625 - 0.5 = 0.125 left. The next fraction that fits is 1/8 (0.125), written as b0.0010.

    Together with b0.1000 above, it's b0.1010 So the final number is:

    b1101.1010

    Get it? Try a few more:

    4.125, 9.0625, 13.75.

    Now, all these conversions so far, align very nicely. But what when they do not?


    Finaly, our problem.

    1 + 2 = 3. In binary, let's padd it to 4 bits: 1 -> the biggest binary that fits is b0010. 2 -> the biggest thing that fits is b0010.

    b0001 + b0010 = b0011.

    If we convert the result back: b0011 -> to decimal, we get 3.

    Okay? Good.


    Now let's try 0.1 + 0.2.

    • decimal 0.1 => 1 / 10.

    How do we get it in binary? Let's find the biggest fraction that fits: 1/16, or 0.0625, or b0.0001 What's left is 0.1 - 0.0625 = 0.0375. Next binary that fits: 1/32 or 0.03125 or b0.00001. We're left with 0.00625. Next binary that fits is 1/256
    ... etc etc until we get to:

    decimal 0.1 = b0.0001100110

    We can do the same with 0.2 -> b0.0011001100.

    Now, let's add those two:

    ` b0.0001 1001 10 +b0.0011 0011 00

    b0.0100 1100 10 `

    Right? So far so good. Now, if we go back to decimal, it should come out to 0.3.

    So let's try it: 0/2+1/4+0/8+0/16+1/32+1/64+0/128+0/256+1/512+0/1024 => 0.298828125

    WHAAAT?

  • DIY NAS build in progress
  • Oh, I don't want this to be a PC. I have plenty of CPU power for what I do, this has a different purpose.

    I'm not planning to run anything much on those Celerons - it's mostly just a file server. People do that with a RasPi - a 4-core CPU is going to blow it out of the water I think.

  • DIY NAS build in progress
  • I also wanted some Ryzens, but my requirements were different. I did not want so much computational power, as much as I wanted low power. Combined with the price and availability, this works good enough for mne. We'll see in the long run.

  • DIY NAS build in progress
  • Yes, in fact! Two main reasons.

    • I wanted low-power, this is mostly gonna sit in the closet and serve files around. Even ARM CPUs like the RasPi can do that. But I didn't want it to be too weak, in case I wanted a simple service or two, this still has extra oomph. This isn't too powerful, but it is a 64-bit x86 CPU.

    • I also wanted some ports. This has 4 SATA ports. It's supposed to be a NAS. It has a Gbit ethernet - I don't have a Gbit network at home so this is good enough for now, and I can expand it somewhat. It has USBs, expansion slots etc.

    • those two combined resulted in a few selections, AsRock's mini-ITX boards with integrated CPUs are quite good choices in this space.

    • I wanted low power consumption. I could have gone with a slightly stronger ‎J5040-ITX perhaps, but it's also using just slightly more power.

    • it's also cheaper, the mobo with the CPU cost me 120€. The j5040 I mentioned would be a bit more - not a lot but still noticable.

    • I wanted silent, and this board and CPU is passively cooled. If I had money, I would get SSDs for storage as well (less power, less noise) but it's a LOT more expensive.

    I know there are other CPUs in this space but in the end you have to pick one so I did.

  • DIY NAS build in progress
  • Thanks! I ordered a SATA SSD already, and I did plan to read about the E key slot later, but for now I'm good. The board has 4 SATA slots, so I will either have to have an USB OS disk or an adapter like this, but for now I'll just go with what I know.

    Do you know what are the speeds like on that Sintech or similar adapter? I don't really need NVMe speeds, it's a simple OS disk, but I wouldn't like to go down to something bellow regular SSD speeds.

  • DIY NAS build in progress

    I'm building a NAS for the first time on my own, so I wanted to share the story so far here.

    I'm not a stranger to custom builds, in fact I don't think I ever bought an assembled PC (not counting second hand 386 box a million years ago). But this is my first small, low power build, so it's not perfect, I already ran into a wall (more later).

    I base the build on an AsRock mini-ITX board, the CPU is included, it's passively cooled, low power consumption but still powerful for a NAS. I'm sticking it into a Node 304 Fractal Design case. Here's the full list of parts I got:

    • AsRock J4125-ITX board with a Celeron 4125 (4-core CPU)
    • 8GB DDR4 RAM (a Crucial kit)
    • a 500GB NVMe SSD (which I can't use)
    • a couple of Seagate IronWolf 4TB drives
    • 90W PicoPSU and some no-name power brick
    • Fractal Design Node 304 mini-ITX case.

    I planned to have an SSD for OS, these two disks for my photography and media, and then later on expand with more storage (preferably SSD, when I can afford it).

    As mentioned, I messed up: the M2 slot on the motherboard is a "Key E" slot. I never bothered with these keys before, so I didn't know that a Key E slot does not have a SATA protocol, it won't take my SSD.

    Another thing, the PicoPSU is a 20-pin power supply, and the board has a 24-pin slot. It should still be fine, the specs say that this is still okay, but I'll have to see. According to my back-of-the-napkin calculations, 90 Watts should be enough power for the mobo and CPU, the SSD and the two spinning disks.

    Anyway I'll get a regular SATA SSD tomorrow and see how it's shaping up. Let me know if you want me to post more on my progress/end result or if you have any questions.

    45
    Sunflower

    Taken for the 52frames.com challenge last week. I have a few more shots on my (relatively new) photo site.

    1
    What's a good used ThinkPad - or other laptop - in 2023?

    What would be a good investment now? I want no-frills Linux support, good CPU, lots of RAM, decent screen. If I'm actually working, I'm almost always docked, but when not, I would not mind a good battery as well. I want this primarily for personal use. I don't mind upgrading parts myself (if that's still possible), like getting a stronger SSD or something.

    I used to own a T420 (and some other ThinkPads as well, but this one was used). It was an incredible investment at the time, used laptop price, build quality and feature on par with laptops 6, 7, 8 years younger. I wonder if this is still something you can get away with.

    3
    InitialsDiceBearhttps://github.com/dicebear/dicebearhttps://creativecommons.org/publicdomain/zero/1.0/„Initials” (https://github.com/dicebear/dicebear) by „DiceBear”, licensed under „CC0 1.0” (https://creativecommons.org/publicdomain/zero/1.0/)ZL
    zlatko @programming.dev
    Posts 3
    Comments 48