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Comment by EarthIsHome | Hacker News Reader

I didn't know grep! I've seen grep used as a verb enough times that the word "grep" just intuitively seems to describe what it does: grep things.

I was hoping dd would be listed.[0]

Edit: digging a little deeper into [0], there's a Unix Acronym List linked [1]. There seems to be various definitions for dd. One definition says that dd stands for copy and convert, but since cc was already taken for the C compiler, dd was used.

[0]: https://unix.stackexchange.com/questions/6804/what-does-dd-s...

[1]: https://groups.google.com/forum/#!topic/comp.unix.misc/LbLTa...

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I always liked that dd story but it's probably not true -- it's based on the DD command in IBM JCL, which stood for "data definition".

Nothing says it can't be both "incremented cc" and "DD from JCL" - especially when you consider the way the options are given, which I've heard from some Bell Labs sources long ago originated as joke on JCL

I've also heard disk dump, but this might be a backronym.

g/re/p lives on as :g in vim, it's kind of fun to remember its heritage to ed. There is also :v which is analogous to grep -v.

Computerphile did a great video with Brian Kernighan on "Where GREP Came From"

https://www.youtube.com/watch?v=NTfOnGZUZDk

Isn't dd "disk duplication"?

Or if swap your of and if arguments, disk destroyer. :)

Nope. As per Dennis Ritchie's 2004 comment in https://groups.google.com/g/alt.folklore.computers/c/HAWoZ8g... , the "dd" command's name is a joke about the DD ("Data Definition") card in IBM's horrid Job Control Language (JCL). You'd need a DD card for each and every file that your program was going to access, and the name had to be specified ahead of time.

A typical example, from https://programmerspub.com/learn/mainframe/jcl/the-dd-statem... :

  //OUTPUT  DD DSN=PROGPUB.FLATFILE.OUTPUT,DISP=(NEW,CATLG,DELETE),
  //            RECFM=FB,LRECL=80,SPACE=(800,(2,5))

You'd think so, since that's the main thing it's used for anymore. But check the output of --help. Changing case, ascii to ebcdic, doesn't really fit the bill.

You don't re-encode your disk from ASCII to EBCDIC when duplicating it? Have I been doing it wrong all of these years?

casting my harddrive to lowercase does sound like kind of experiment that'd only cross your mind after 6 months of lockdown.

I would start on media files, ideally formats that have a little bit of forgiveness where they'll try to render or play arbitrary sequences of bytes rather than just failing to parse them.

It shouldn't be because it will work with normal files just fine. E.g. if you want to image a disk, `dd if=/dev/sdc of=sdc.img` and silly things like `dd if=/etc/passwd of=/root/~passwd` work too. Also it has a convert function so it's not strictly just for duplication.

It's actually “convert and copy” but the command name `cc` was already occupied by “C compiler”, so they just incremented each letter to `dd`. `dd` can convert-and-copy any device, not just disks.

As can be seen at https://unix.stackexchange.com/q/6804/5132 , this wrong answer is still more popular than the right one that is supported by Dennis Ritchie. A salutary lesson in believing things to be true because they seem humorous or are popular.

Forgive GP for not knowing which Bible to read and at whose altar to prostrate themselves. Like every religion Unix has its goyim and infidels that need to be flogged and flagellated so they can achieve proper enlightenment.

As it's inconceivable to conflict both Ritchie and the jargon file when talking about UNIX history, I stand corrected. However, I do remember seeing 'cc was already taken, hence dd' in some old linux documentation.

And if you thought my parent comment was a bad joke, maybe read the man page:

https://www.systutorials.com/docs/linux/man/1-dd/

Did anyone else think it was GNU-rep, presumably a reference to an older UNIX command?

Same--up until now I "knew" that grep stood for "GNU regular expression parser." Always good to have a reminder to question all the other things we "know."

> Always good to have a reminder to question all the other things we "know."

See also the 'HISTORY' section in BSD manual pages, then check their GNU clones.

Yep. When I was a little sysadminlet, I asked my mentor that exact question. He had a good laugh out of it.

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