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Bug #10003

/bin/dd skip= does not use seek( ) as promised in manual

Added by Toomas Soome 11 months ago. Updated 11 months ago.

Status:
New
Priority:
Normal
Assignee:
-
Category:
cmd - userland programs
Start date:
2018-11-22
Due date:
% Done:

0%

Estimated time:
Difficulty:
Medium
Tags:
needs-triage

Description

       skip=n

           Skips n input blocks (using the specified input block size) before
           starting to copy. On seekable files, the implementation reads the
           blocks or seeks past them. On non-seekable files, the blocks are
           read and the data is discarded.

However, the dd still does always read the blocks in while loop, resulting with long execution time compared to gnu dd.

test with something like:

dd if=/dev/dsk/c3t0d0 bs=512 skip=2097152 count=1 of=/dev/null

History

#1

Updated by Toomas Soome 11 months ago

  • Description updated (diff)
#2

Updated by Marcel Telka 11 months ago

Note: iseek should work as expected.

#3

Updated by Toomas Soome 11 months ago

Marcel Telka wrote:

Note: iseek should work as expected.

Yes, except, if the input does not support seek, it will exit dd.

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