this post was submitted on 05 Dec 2023
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    shamelessly stolen from nixCraft on mastodon

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    [–] Dasnap@lemmy.world 110 points 11 months ago

    Your USB is probably named '/' or '~' so give that a go.

    [–] impolitecarry@lemmy.wtf 74 points 11 months ago (2 children)

    When you hit enter on the DD command, and your main storage light suddenly starts flashing.

    [–] FooBarrington@lemmy.world 53 points 11 months ago (2 children)

    When you hit enter on the DD command, and your eyes suddenly start flashing.

    [–] 567PrimeMover@kbin.social 56 points 11 months ago* (last edited 11 months ago)

    Little Jimmy wanted to try Fedora, But little Jimmy is no more. For what he thought was his external drive, was actually his cerebral core

    [–] WhiskyTangoFoxtrot@lemmy.world 3 points 11 months ago (1 children)
    [–] FooBarrington@lemmy.world 2 points 11 months ago

    That was great :D though I'm afraid that this is kind of me, considering I have a file server on my vacuum robot

    [–] Andrew15_5@mander.xyz 7 points 11 months ago* (last edited 11 months ago) (1 children)

    So? I'm just creating an 8 GiB swap file.

    [–] Redjard@lemmy.dbzer0.com 6 points 11 months ago (1 children)

    Try btrfs, where with only 5 hours of research you can create a swap file without writing the entire file.
    Also there is no other option, the 5h are non-optional.

    After doing that twice, In my / now lives

    /swapfile-howto

    # this is btrfs not a normal file system.
    # We have to create and allocate the file in a btrfs friendly way,
    # and tell btrfs to not move or segment it.
    
    touch /swapfile999
    chmod 600 /swapfile999
    truncate -s 0 /swapfile999
    chattr +C /swapfile999
    fallocate -l 999G /swapfile999
    mkswap /swapfile999
    swapon /swapfile999 -p 200
    

    [–] ashe@lemmy.starless.one 11 points 11 months ago (1 children)

    I admire your dedication, but you really could've just done this

    btrfs fi mkswapfile --size 16G /swap
    swapon /swap
    
    [–] Redjard@lemmy.dbzer0.com 7 points 11 months ago

    Huh, thank you for telling me, I'll amend the file with that info. This being a thing will probably spare many the troubles I experienced.

    I did some digging to reconstruct what happened in my case. The file was created on 2022-12-08, and I remember this being after I rediscovered my earlier approach, from - going by my browsing history - mid september 2022. I worked through plenty of wiki pages at the time, including the btrfs docs on swapfiles, where I probably got my commands. The truncate in there to fix earlier mistakes is something I would keep in, but not add myself, so I must have copied that pages solution. Interestingly, going by archive.org, between dec 02 and dec 13 the documentation on btrfs fi mkswapfile was added to that page.
    I am in no way confident in my memory here, but I vaguely recall seeing that command, and being somewhat surprised to not remember it from earlier. That confusion may have even contributed to pushing me to create the file.
    Had I seen it, I probably would have tried the command and seen it not exist. Following the note of btrfs 6.1 being required, I would have checked the version and seen that my distro didn't have btrfs-progs 6.1, not even as an alpha on the development channel.
    I may also have remembered there being multiple commands needed earlier, and not wanting to deviate from the proven method dismissed the apparently simpler method.

    To complete this very meaningful and productive story, on 2022-12-23 my distro got the early christmas present of btrfs-progs 6.1 as an unstable release in the dev channel. After many retractions and republishings of a total of 4 subversions, on 2023-03-04 the first stable release of 6.1.x was made available.

    I was 6 months early. Or rather the btrfs devs were 6 months late.

    Edit (actually not edit because I didn't send yet):
    I actually checked the repo and the documentation changed on dec 06. Here is the commit. The corresponding release occurred on dec 22.
    Dumping 30mins into writing this actually resulted with a memorable story. By chance I stumbled over the documentation of a new feature, 2 days after it had been written, but 2 weeks before even the first alpha release containing it was created.

    [–] iopq@lemmy.world 72 points 11 months ago (3 children)

    You used something called disk destroyer, and you just found out why

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    [–] MonkderZweite@feddit.ch 51 points 11 months ago (4 children)
    [–] stjobe@lemmy.world 8 points 11 months ago

    That was an interesting read, thank you!

    [–] Molten_Moron@lemmings.world 7 points 11 months ago

    I haven't touched dd since I read that about a year ago, super interesting!

    For people that use dd because they like the progress bar, I highly recommend pv.

    [–] azertyfun@sh.itjust.works 5 points 11 months ago* (last edited 11 months ago) (2 children)

    Except the proposed alternative should not be cp or pv, but dd bs=4M oflag=direct,sync status=progress.

    I feel like I'm taking crazy pills with all the advice in this thread, because for USB keys you will otherwise end up instantly filling the write cache... which will block the apparent progress of the copy operation (so why even use pv since all you're doing is measuring your RAM speed and available cache size) as well as heavily slow down (even potentially partially freeze in some circumstances) the rest of your system as the kernel is running out of free pages and can't flush caches fast enough due to the slow-ass write speeds of usb keys.

    * (Alternatively there is a kernel setting somewhere to disable caching globally for a block device... but in most cases caching is good, just not when you're flashing an ISO).

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    [–] backhdlp@lemmy.blahaj.zone 47 points 11 months ago (3 children)

    Another advantage of having a NVMe SSD, hard to confuse /dev/nvme0n1p2 with /dev/sda1

    [–] bzLem0n@lemmy.ca 16 points 11 months ago (3 children)

    It's even easier to prevent confusion if you use /dev/disk/by-id/ id's, it only took a few times of overwriting the wrong disk to figure that out.

    [–] backhdlp@lemmy.blahaj.zone 4 points 11 months ago

    I think that does the opposite for me lol

    [–] Goodtoknow@lemmy.ca 2 points 11 months ago (3 children)

    How can I figure out which direct device is associated with a specific id?

    [–] Nithanim@programming.dev 6 points 11 months ago

    Not sure if it is equal on all distros but on every one I have used it's a readable string of muliple components. One of them is "usb" for a usb mass storage, so if it is the only one you have connected to your computer it is very obvious. For like sata disks it has the manufacturer and serial on it so you can match what drive it is you want to write to. Also, the name is pretty unique (on your sysytem at least, globally I don't know), so even if you swap hardware around, you cannot write to the wrong storage if you got the right name. Like "sdb" can be reassigned, but the id is an id.

    [–] backhdlp@lemmy.blahaj.zone 6 points 11 months ago

    They're symlinks, so you can just ls -l /dev/disk/by-id, and you can see what is what.

    [–] problembasedperson@lemmy.dbzer0.com 3 points 11 months ago* (last edited 11 months ago)

    ˋblkidˋ or take a look around /dev, devices are symlinked to their various attributes.

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    [–] Holzkohlen@feddit.de 7 points 11 months ago

    I just make use of my paranoia, so I triple and quadruple check. Then get a coffee and quadruple check again. Never messed up once

    [–] MeanEYE@lemmy.world 6 points 11 months ago

    Even if it's similar names I'd normally plug in USB, do dmesg, then issue a command with latest device name.

    [–] backhdlp@lemmy.blahaj.zone 45 points 11 months ago (4 children)

    Fun fact: you can use cat image.iso > /dev/device and it (should) just works.

    [–] mumblerfish@lemmy.world 52 points 11 months ago

    Yay, more ways to (accidentally) destroy my data!

    [–] PoolloverNathan@programming.dev 8 points 11 months ago

    Or pv if you want a progress bar.

    [–] AffineConnection@lemmy.world 3 points 11 months ago* (last edited 11 months ago)

    Assuming /dev/device is not a symbolic link, you might as well

    cp image.iso /dev/device
    [–] ExLisper@linux.community 2 points 11 months ago

    Sure, if you're a little bitch.

    [–] speaker_hat@lemmy.one 30 points 11 months ago

    That's why it called dd: don't dare

    [–] gunpachi@lemmings.world 21 points 11 months ago (1 children)

    I always use the status=progress argument.

    [–] ook_the_librarian@lemmy.world 31 points 11 months ago (1 children)

    That ain't why that light isn't blinking.

    [–] uis@lemmy.world 5 points 11 months ago

    Because this USB stick doesn't have light

    [–] foyrkopp@lemmy.world 19 points 11 months ago

    Anyone who hits enter on a dd command without triple-checking it gets exactly what they deserve.

    [–] Hupf@feddit.de 14 points 11 months ago

    I always prefer the bulkier /dev/disk/by-id/ symlinks because of this

    [–] hemmes@lemmy.world 7 points 11 months ago

    Goofoyou, goofoyou!

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