Puppy Linux Discussion Forum Forum Index Puppy Linux Discussion Forum
Puppy HOME page : puppylinux.com
"THE" alternative forum : puppylinux.info
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

The time now is Thu 21 Nov 2019, 10:20
All times are UTC - 4
 Forum index » Taking the Puppy out for a walk » Misc
Unix Trivia
Moderators: Flash, JohnMurga
Post new topic   Reply to topic View previous topic :: View next topic
Page 1 of 1 [11 Posts]  
Author Message
rufwoof


Joined: 24 Feb 2014
Posts: 3631

PostPosted: Thu 07 Nov 2019, 23:06    Post subject:  Unix Trivia  

Why is the dd command called "dd" ?

.
.
.

dd = convert and copy command, but as c compile (cc) was already used it was decided to shift up the alphabet for the 'convert and copy' command.

Second video https://catonmat.net/why-unix-commands-are-short 30:40

_________________
( ͡° ͜ʖ ͡°) :wq
Fatdog multi-session usb

echo url|sed -e 's/^/(c/' -e 's/$/ hashbang.sh)/'|sh

Last edited by rufwoof on Fri 08 Nov 2019, 06:37; edited 1 time in total
Back to top
View user's profile Send private message 
jafadmin

Joined: 19 Mar 2009
Posts: 1004

PostPosted: Thu 07 Nov 2019, 23:36    Post subject:  

It actually comes from the IBM Job Control Language for batch processing.
The following example, using JCL, DD is used to copy a file on OS/360:
Code:

//IS198CPY JOB (IS198T30500),'COPY JOB',CLASS=L,MSGCLASS=X
//COPY01   EXEC PGM=IEBGENER
//SYSPRINT DD SYSOUT=*
//SYSUT1   DD DSN=OLDFILE,DISP=SHR
//SYSUT2   DD DSN=NEWFILE,
//            DISP=(NEW,CATLG,DELETE),
//            SPACE=(CYL,(40,5),RLSE),
//            DCB=(LRECL=115,BLKSIZE=1150)
//SYSIN  DD DUMMY
Back to top
View user's profile Send private message 
mistfire

Joined: 04 Nov 2008
Posts: 1255
Location: PH

PostPosted: Fri 08 Nov 2019, 05:44    Post subject:  

DD

DUPLICATE
DISK
Back to top
View user's profile Send private message 
rufwoof


Joined: 24 Feb 2014
Posts: 3631

PostPosted: Fri 08 Nov 2019, 06:36    Post subject:  

Code:
# dd --help

Quote:
Usage: dd [OPERAND]...
or: dd OPTION
Copy a file, converting and formatting according to the operands.
.
.

_________________
( ͡° ͜ʖ ͡°) :wq
Fatdog multi-session usb

echo url|sed -e 's/^/(c/' -e 's/$/ hashbang.sh)/'|sh
Back to top
View user's profile Send private message 
Burn_IT


Joined: 12 Aug 2006
Posts: 3585
Location: Tamworth UK

PostPosted: Fri 08 Nov 2019, 11:31    Post subject:  

jfadmin No it doesn't.

The DD statement in JCL stands for Data Definition and has nothing whatsoever to do with copying.

The program IEBGENER is the thing that does the copying.
SYSUT1 is the source file
and SYSUT2 is the target file
in your example.

_________________
"Just think of it as leaving early to avoid the rush" - T Pratchett
Back to top
View user's profile Send private message 
musher0

Joined: 04 Jan 2009
Posts: 14484
Location: Gatineau (Qc), Canada

PostPosted: Fri 08 Nov 2019, 11:55    Post subject:  

Bump one letter up in the Latin alphabet? I see:
dd = donvert and dopy. Laughing
whatever that means! Twisted Evil

Following a similar reasoning, conky is actually a donkey!!! Laughing Hee-haw!

_________________
musher0
~~~~~~~~~~
Je suis né pour aimer et non pas pour haïr. (Sophocle) /
I was born to love and not to hate. (Sophocles)
Back to top
View user's profile Send private message 
jafadmin

Joined: 19 Mar 2009
Posts: 1004

PostPosted: Fri 08 Nov 2019, 18:33    Post subject:  

Burn_IT wrote:
jfadmin No it doesn't.

The DD statement in JCL stands for Data Definition and has nothing whatsoever to do with copying.

The program IEBGENER is the thing that does the copying.
SYSUT1 is the source file
and SYSUT2 is the target file
in your example.


https://en.wikipedia.org/wiki/Dd_(Unix)#History
Back to top
View user's profile Send private message 
p310don

Joined: 19 May 2009
Posts: 1426
Location: Brisbane, Australia

PostPosted: Fri 08 Nov 2019, 19:13    Post subject:  

I read somewhere it was data duplicate(or)
Back to top
View user's profile Send private message 
Burn_IT


Joined: 12 Aug 2006
Posts: 3585
Location: Tamworth UK

PostPosted: Fri 08 Nov 2019, 19:32    Post subject:  

Read what I said!
I said IN JCL

The dd statement in JCL is used to link a logical filename in a program to a physical data stream somewhere in the real world.
It has nothing to do with what that data is used for, though it may tell the operating system what state to leave that data in when it is finished with it.

_________________
"Just think of it as leaving early to avoid the rush" - T Pratchett
Back to top
View user's profile Send private message 
jafadmin

Joined: 19 Mar 2009
Posts: 1004

PostPosted: Fri 08 Nov 2019, 22:52    Post subject:  

Burn_IT wrote:
Read what I said!
I said IN JCL

The dd statement in JCL is used to link a logical filename in a program to a physical data stream somewhere in the real world.
It has nothing to do with what that data is used for, though it may tell the operating system what state to leave that data in when it is finished with it.


http://ibmmainframes.com/about9267.html


.
Back to top
View user's profile Send private message 
Burn_IT


Joined: 12 Aug 2006
Posts: 3585
Location: Tamworth UK

PostPosted: Mon 11 Nov 2019, 09:58    Post subject:  

And your point is??
In all those examples there is a program involved to do the copying.

Even if you do want to use JCL to do things like allocate space for a file or catalogue a file, you still have to have a "PGM" statement (an executable program).
The most used program for this is IEFBR14 which consists of just a return statement.

In those examples the program is the sort utility.

_________________
"Just think of it as leaving early to avoid the rush" - T Pratchett
Back to top
View user's profile Send private message 
Display posts from previous:   Sort by:   
Page 1 of 1 [11 Posts]  
Post new topic   Reply to topic View previous topic :: View next topic
 Forum index » Taking the Puppy out for a walk » Misc
Jump to:  

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


Powered by phpBB © 2001, 2005 phpBB Group
[ Time: 0.0837s ][ Queries: 12 (0.0274s) ][ GZIP on ]