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Because it can be a lot slower. dd is low level, hence powerful and dangerous.
And, if we are going down that rabbit hole, you don't need cat[1]
“The purpose of cat is to concatenate (or "catenate") files. If it's only one file, concatenating it with nothing at all is a waste of time, and costs you a process.”
Author is wrong bs IS useful, try to dd one hard drive to another without reasonable bs (1-8M) with and without and you will see a difference.
Earlier quoted context omitted.
If one of the biggest the biggest lifetime regrets is a $50k financial loss, your friend is doing pretty well.
$50k is a massive sum for a lot of people...
One thing I'll often use dd for is recovering data from a failing drive. Can head ignore read errors? dd can. As far as I'm concerned, dd is lower-level than most of the other utilities and provides more control over what's happening. The author does have a point that the syntax is strange though.
>One thing I'll often use dd for is recovering data from a failing drive. Funnily enough, I ended up using it to accidentally name the wrong drive in the argument, and lost years of photos, music, video etc. though I suppose I can't blame dd for that :)
An even easier solution: don't make people fall into the command line to format a USB reliably. The command line should be reserved for times where you need the fine grain control to do something that DD is meant to do. A GUI should implement everything else in a reliable way that doesn't break half the time or crash on unexprected input.
There's one good (?) reason to use dd with devices: it specifies target in the same command. For devices, writing to them usually requires root privileges, so it's easy to: sudo dd .... of=/dev/... But there's no trivial cat equivalent: sudo cat ... > target Will open target as your current user anyway. You can play around with tee and redirection of course. But that's getting more complicated than the original.
sudo sh -c 'cat some.img > /dev/sdb'
cat some.img | sudo tee /dev/sdb > /dev/null
I have an ARM/linux installer script that writes the u-boot image to a specific offset before the first partition:
dd if=${UBOOT_DIR}/MLO of=$LO_DEVICE count=1 seek=1 bs=128k
dd if=${UBOOT_DIR}/u-boot.img of=$LO_DEVICE count=2 seek=1 bs=384k
An even easier solution: don't make people fall into the command line to format a USB reliably. The command line should be reserved for times where you need the fine grain control to do something that DD is meant to do. A GUI should implement everything else in a reliable way that doesn't break half the time or crash on unexprected input.
If you mess up the syntax on a dd invocation, a nice thing happens: nothing.
Use a shell command and pipes, and your command better be perfect before you hit return.
There's one good (?) reason to use dd with devices: it specifies target in the same command. For devices, writing to them usually requires root privileges, so it's easy to: sudo dd .... of=/dev/... But there's no trivial cat equivalent: sudo cat ... > target Will open target as your current user anyway. You can play around with tee and redirection of course. But that's getting more complicated than the original.
sudo cp image.iso /dev/sdbAn even easier solution: don't make people fall into the command line to format a USB reliably. The command line should be reserved for times where you need the fine grain control to do something that DD is meant to do. A GUI should implement everything else in a reliable way that doesn't break half the time or crash on unexprected input.