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Most new (and some old) linux users know
dd for one purpose. That is, of
course, creating a bootable flashdrive with a linux iso. Many of the most
popular guides and tutorials online show something like
dd if=file.iso of=/dev/sdx && sync as if that’s the only way you can put an iso on a
flashdrive. It technically will work, but there are better ways to copy a file
on linux. For example,
cp file.iso /dev/sdx will do the same thing and you
don’t need to worry about block size or any of that nonsense, since
actually meant for copying files.
Basically anything that will read/write a file can be used:
cp file.iso /dev/sdx cat file.iso > /dev/sdx tee < file.iso > /dev/sdx pv file.iso > /dev/sdx
Contrary to popular belief
dd doesn’t stand for “disk duplicator” or anything
similar. In fact, it doesn’t know anything about disks and the only reason it
can interact with block devices is because linux presents drives and partitions
as simple files under
dd for this purpose can actually be a bad
idea because of its unwieldy options that are easy to typo (i and o are next to
each other on the keyboard). When you’re working with sudo and block devices
a tiny typo could mean wiping your drive.
dd is meant to be used for more specific read and write operations – like
this little command that will generate a random password for you by reading 30
/dev/urandom and then converting the binary output to base64.
dd if=/dev/urandom count=1 bs=30 | base64
My personal favourite tool is
pv, which is fairly standard, but not very
well known. It can be used in a pipeline to display progress and can
conveniently read a file like in
pv file.iso > /dev/sdx.
I Changed the example dd command to use a byte size of 30 instead of 20. This allows base64 to create a clean password without a padding character at the end. Henry pointed this out in my public mailing list. Thanks!