shamelessly stolen from nixCraft on mastodon
Your USB is probably named ‘/’ or ‘~’ so give that a go.
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I actually did this once. My USB was on /dev/sda instead of sdb and I didn’t bother to check. It took me like 2 days to fix it because you can’t just delete partitions and start over normally, it changes some flags on your drive that you need to manually reset for them to be usable again. Fun times.
I once mistyped and didn’t realize until it was done that I wrote a Fedora ISO to the home partition. I didn’t even realize what I did until everything was done and wiped out.
When you hit enter on the DD command, and your main storage light suddenly starts flashing.
When you hit enter on the DD command, and your eyes suddenly start flashing.
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
Here is an alternative Piped link(s):
https://www.piped.video/watch?v=ajW2fDy41fY
Piped is a privacy-respecting open-source alternative frontend to YouTube.
I’m open-source; check me out at GitHub.
That was great :D though I’m afraid that this is kind of me, considering I have a file server on my vacuum robot
You used something called disk destroyer, and you just found out why
Disk Duplicator is a destroyer? Man, I used to image so many drives with DD back in my helpdesk days…
dddoes not stand for “disk duplicator”. That’s a modern backronymization that doesn’t reflect the original general usage of the command which is to “convert and copy”. Efficiently (with respect to I/O) copying raw data is only one of its intended purposes; it also converts text encodings.fine Data Definition.
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That’s my nickname too.
No, he said ‘disk’.
Same thing, we know it’s a little floppy 💾
Why is the save button floppy, I don’t understand!?!?
In case you are being serious, the save icon is a picture of a “floppy disk” a removable media that was extremely prevalent in the 80s-90s these devices could store get this 1.44 MB of data. IIRC Windows 95 came out on 13 of these puppies that you had to put in one after the other to actually install windows. This was also a similar situation for games.
Disk Destroy December. Get to it folks!
You might as well call
cpthe same thingcp source "`realpath destination`"
Obligatory useless use of dd comment.
That was an interesting read, thank you!
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.
Except the proposed alternative should not be
cporpv, butdd 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
pvsince 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).
so why even use pv since all you’re doing is measuring your RAM speed and available cache size
This is probably why pv progress fills in a second but is only done after a few minutes. Nonetheless, shell redirect, cat, cp work fine and handle blocksize and cache dynamically.
Your worst case scenario never happened to me after years of using pv/cp for flashing sticks/overwriting/copying partitions, even with some …risky mount settings. Honestly doesn’t make much sense to me either. Again, dd isn’t some sort of magical safe handle to make the process progress smoothly. Like i use to say, dd is a skalpell, not a shovel.
I mean yeah, the bits end up where they should. It’s just that the speed/progress indication is near useless with pv since at the end of the copy you still need to wait for the entire write buffer to be flushed (2 GiB in my experience, which can take several minutes).
So IMO
ddwith at leastoflag=osync,odirectis safer thancpandpvwith which a newbie might forget to runsyncand unplug the usb key immediately, so they’ll be missing a lot of data.Maybe some people use
ddfor the wrong reason, it’s their problem, but the solution is to usedd bs=4M oflag=osync,odirect, not to usecp.
It was less useless for that purpose when
cpandcatwere less I/O efficient compared toddwith the appropriate block size, which isn’t as much the case now as it used to be.
Another advantage of having a NVMe SSD, hard to confuse /dev/nvme0n1p2 with /dev/sda1
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.
I think that does the opposite for me lol
How can I figure out which direct device is associated with a specific id?
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.
They’re symlinks, so you can just
ls -l /dev/disk/by-id, and you can see what is what.ˋblkidˋ or take a look around /dev, devices are symlinked to their various attributes.
When I accidentally decimated my external hard drive, it had NTFS cause there were a few windows machines I would plug it in. Then I reformatted the disk but then I thought to myself, should I have another partition for my Linux machine because that drive gets corrupted and then I need to plug to a Windows machine to repair it once in a while. Then I created an ext4 partition on the disk. Then a few days after I shrinked the NTFS partition and extended the ext4 to the whole disk. Now that disk only has one partition called sda2. Which is kinda weird but makes it easier to distinguish from others disks on the system.
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
Even if it’s similar names I’d normally plug in USB, do
dmesg, then issue a command with latest device name.
Fun fact: you can use
cat image.iso > /dev/deviceand it (should) just works.Yay, more ways to (accidentally) destroy my data!
Or
pvif you want a progress bar.Assuming
/dev/deviceis not a symbolic link, you might as wellcp image.iso /dev/deviceSure, if you’re a little bitch.
That’s why it called dd: don’t dare
I always use the status=progress argument.
That ain’t why that light isn’t blinking.
Because this USB stick doesn’t have light
Anyone who hits enter on a dd command without triple-checking it gets exactly what they deserve.
I always prefer the bulkier /dev/disk/by-id/ symlinks because of this
Be me
Want to install archlinux just to try it
Accidentally installed archlinux live environment on my main hard disk using dd
Goofoyou, goofoyou!
