dd curiosity

Billy G. Allie bga at bgalli.eds.com
Tue Jan 2 17:33:00 AEST 1990

bill at twwells.com (T. William Wells) writes:

:In article <396 at zok.UUCP> mark at zok.UUCP (Mark W. Snitily) writes:
::   ...
:: But, if I read 4 sectors from the partition starting at sector 20000,
:: the read will take forever to complete, (i.e. we're talking minutes to
:: hours depending upon the skip value):
::       dd if=/dev/rdsk/0p1 of=myfile skip=20000 count=4
:Reads everything from the beginning of /dev/rdsk/0p1 till it gets
:to the place to read.
:: Any ideas of how to speed it up?
:Use seek instead of skip.

Using seek will cause it to seek to block 20000 of the _OUTPUT_ file.
Some versions of dd have an iseek option to seek on the input file.  The
easiest way to find out is to try it and see if it works.  If it doesn't
work, you will have to continue to use (the slow method of using) skip.
____	   | Billy G. Allie	| Internet..: bga at bgalli.eds.com
|  /|	   | 7436 Hartwell	| UUCP......: uunet!edsews!bgalli!bga
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