>> Spurious. dd was always named after JCL dd cards. > > Alright, I'll bite: What did *that* "dd" stand for? I hesitate to leap in front of Dennis Ritchie, but ...
On IBM mainframes, programs are started by "submitting" them in JCL ("Job Control language") to JES, the Job Entry System.
One of the most important statements in JCL is the DD statement. DD stands for "Data Definition". It is used to define the data (duh ;-) that is used when the job is run - input files, output files etc.
JCL has a "unique" flavour; it is utterly unlike normal programming languages and is archane, cryptic, obscure, complex and rude. It is also ugly and stupid. However there is so much JCL in the world that, hell, we still have to live with it - even after thirty years of Unix ;-).
The Unix dd command copies data from one place to another, rather like a typical DD card in a JCL stack.
The "if=", "of=", "bs=", etc, parameters to the Unix dd command retain some of the characteristic syntactic idioms of JCL (not to say that the dd command is as ugly as JCL - it just has a faint echo of the JCL syntax).
For a mainframe guy, the dd command on Unix gives a nice homely touch.
>> Spurious. dd was always named after JCL dd cards.
>
> Alright, I'll bite: What did *that* "dd" stand for?
I hesitate to leap in front of Dennis Ritchie, but ...
Dennis Ritchieが「（cc由来説は）大嘘。JCLのdd文に由来する」と書いた記事に、
Toby Thainが「分かった。じゃあ『dd』ってのは何に由来するの？」と問う記事を書き、
それに対して、Andrew McLarenがJCLの説明を書いている記事だぞ。
disk direct？ (スコア:0)
disk directとかdirect diskとかdirect driveとか勝手に考えてた
Re: (スコア:0)
JCLのDDが由来という説もあるらしいけど、じゃあJCLのDDはどこから来たのか？とやっぱり思うよね。
私の知ってるMVS互換OSではDDはファイル記述子と実際のデータセットを結びつける指示だった。
元をだとればdeviceなんちゃらだったと思われる。
だいたいあってるような気がする。
Re: (スコア:2, 参考になる)
スラドの法則：英語の記事はリンクを張っても誰も読まない
Toby Thain wrote:
> "Dennis Ritchie" wrote
>> Spurious. dd was always named after JCL dd cards.
>
> Alright, I'll bite: What did *that* "dd" stand for?
I hesitate to leap in front of Dennis Ritchie, but ...
On IBM mainframes, programs are started by "submitting" them in JCL ("Job
Control language") to JES, the Job Entry System.
One of the most important statements in JCL is the DD statement. DD stands
for "Data Definition". It is used to define the data (duh ;-) that is used
when the job is run - input files, output files etc.
JCL has a "unique" flavour; it is utterly unlike normal programming
languages and is archane, cryptic, obscure, complex and rude. It is also
ugly and stupid. However there is so much JCL in the world that, hell, we
still have to live with it - even after thirty years of Unix ;-).
The Unix dd command copies data from one place to another, rather like a
typical DD card in a JCL stack.
The "if=", "of=", "bs=", etc, parameters to the Unix dd command retain some
of the characteristic syntactic idioms of JCL (not to say that the dd
command is as ugly as JCL - it just has a faint echo of the JCL syntax).
For a mainframe guy, the dd command on Unix gives a nice homely touch.
Re: (スコア:-1)
いや待て、
ddがJCLのDDだといったのは（そこだけ引用が一段深いから）Dennisじゃないじゃないか。
DennisはDDてなに？て聞いただけ。否定も肯定もしてない。ふざけんな編集。
Dennisが否定したとあるから、あ、そう、と思って読まなかっただけ。
こんな適当なリンク張ってればそりゃだれも読まないだろう。
DDの意味については、とある人が"Data Definition"といっただけだよね。まあそれっぽいけど。
ただし、DDとddが似ているということについては全く同意できない。
Re:disk direct？ (スコア:5, 参考になる)
Toby Thain wrote:
> "Dennis Ritchie" wrote
>> Spurious. dd was always named after JCL dd cards.
>
> Alright, I'll bite: What did *that* "dd" stand for?
I hesitate to leap in front of Dennis Ritchie, but ...
Dennis Ritchieが「（cc由来説は）大嘘。JCLのdd文に由来する」と書いた記事に、
Toby Thainが「分かった。じゃあ『dd』ってのは何に由来するの？」と問う記事を書き、
それに対して、Andrew McLarenがJCLの説明を書いている記事だぞ。