> On Dec 11, 2021, at 11:22 AM, Brian Brombacher <br...@planetunix.net> wrote: > > >> On Dec 11, 2021, at 11:12 AM, u...@mailo.com wrote: >> >> The article: >> https://eklitzke.org/the-cult-of-dd >> >> The content of the article: >> >> The Cult of DD >> Mar 17, 2017 >> You'll often see instructions for creating and using disk images on Unix >> systems making use of the dd command. This is a strange program of >> [obscure provenance](https://en.wikipedia.org/wiki/Dd_(Unix)) that >> somehow, still manages to survive in the 21st century. >> >> Actually, using dd is almost never necessary, and due to its highly >> nonstandard syntax is usually just an easy way to mess things up. For >> instance, you'll see instructions like this asking you to run commands >> like: >> >> # Obscure dd version >> dd if=image.iso of=/dev/sdb bs=4M >> Guess what? This is exactly equivalent to a regular shell pipeline using >> cat and shell redirection: >> >> # Equivalent cat version >> cat image.iso >/dev/sdb >> That weird bs=4M argument in the dd version isn't actually doing >> anything special---all it's doing is instructing the dd command to use a >> 4 MB buffer size while copying. But who cares? Why not just let the >> command figure out the right buffer size automatically? >> >> Another reason to prefer the cat variant is that it lets you actually >> string together a normal shell pipeline. For instance, if you want >> progress information with cat you can combine it with the pv command: >> >> # Cat version with progress meter >> cat image.iso | pv >/dev/sdb >> There's an obscure option to GNU dd to get it to display a progress >> meter as well. But why bother memorizing that? If you learn the pv trick >> once, you can use it with any program. >> >> If you want to create a file of a certain size, you can do so using >> other standard programs like head. For instance, here are two ways to >> create a 100 MB file containing all zeroes: >> >> # Obscure dd version >> dd if=/dev/zero of=image.iso bs=4MB count=25 >> >> # Regular head version >> head -c 100MB /dev/zero >image.iso >> The head command is useful for lots of things, not just creating disk >> images. Therefore it's a better investment of your time to learn head >> than it is to learn dd. In fact, you probably already know how to use it. >> >> I will confess: there are some interesting options that dd has, which >> aren't easily replicated with cat or head. For instance, you can use dd >> to convert a file between ASCII and EBCDIC encodings. So if you find >> yourself doing that a lot, I won't blame you for reaching for dd. But >> otherwise, try to stick to more standard Unix tools. >> >> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> End of article and my questions: >> >> Is the author right in general? > > No. > >> Is the author right for Linux environment? > > No. > >> Is the author right for OpenBSD environment? > > No.
I’ll clarify. Change No to Maybe, only for the examples provided in the article. Otherwise, dd is useful for other actions.
