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ID Category Severity Type Date Submitted Last Update
0000907 [1003.1(2013)/Issue7+TC1] Shell and Utilities Editorial Clarification Requested 2014-12-18 10:42 2019-06-10 08:54
Reporter joerg View Status public  
Assigned To
Priority normal Resolution Accepted As Marked  
Status Closed  
Name Jörg Schilling
Organization
User Reference
Section dd
Page Number 2607
Line Number 84604
Interp Status Approved
Final Accepted Text Note: 0002608
Summary 0000907: dd behavior for count= parameter is underspecified
Description most dd implementations behave as if there was no count= parameter
in case that count=0 was specified.
Desired Action Make the behavior for count=0 unspecified.

On page 2607, line 84604 change:

count=n Copy only n input blocks.

to:

count=n Copy only n input blocks. The behavior is unspecified when n is 0.
Tags tc2-2008
Attached Files

- Relationships

-  Notes
(0002523)
shware_systems (reporter)
2015-01-13 06:24

While not explicit at that point in the text, it appears the specified behavior is to print the status lines in the STDERR section and return EXIT_SUCCESS, as it is always possible to process 0 blocks. What is missing more, to me, is whether an attempt at opening the if= or of= files should be done when the implied "do nothing" of count=0 is found, possibly causing a different exit code if they are not accessible, and whether an output file should be truncated as described under STDOUT and Output Files sections. Also, if EOF is reached before a count=1 or higher blocks have been processed, is this considered an insufficient data error or similar to seek larger than file size? As these relate to possible unexpected data loss if implementations differ, it seems leaving it unspecified not the way to go.
(0002524)
joerg (reporter)
2015-01-13 10:42

You seem to miss the point as you seem to believe that count=0 means
do nothing.

This is in conflict with all dd implementations that have a historic base.

As the general rule for POSIX is not to invalidate historic implementations
in special if this is related to corner cases, it seems to be a bug in POSIX
that there is no explanation that allows to understand count=0 as infinity.
(0002608)
geoffclare (manager)
2015-03-26 16:00
edited on: 2015-03-27 10:55

Interpretation response
------------------------
The standard states the requirements for the count=n operand, and
conforming implementations must conform to this. However, concerns
have been raised about this which are being referred to the sponsor.

Rationale:
-------------
There are two existing implementation behaviors and the standard only allows
one of them.

Notes to the Editor (not part of this interpretation):
-------------------------------------------------------

On page 2607, line 84604 change:

count=n Copy only n input blocks.

to:

count=n Copy only n input blocks. If n is zero, it is unspecified whether no blocks or all blocks are copied.

(0002628)
ajosey (manager)
2015-04-17 09:52

Interpretation Proposed: 17 April 2015
(0002670)
ajosey (manager)
2015-05-18 09:06

Interpretation Approved: 18 May 2015

- Issue History
Date Modified Username Field Change
2014-12-18 10:42 joerg New Issue
2014-12-18 10:42 joerg Name => Jörg Schilling
2014-12-18 10:42 joerg Section => dd
2014-12-18 10:42 joerg Page Number => 2607
2014-12-18 10:42 joerg Line Number => 84604
2015-01-13 06:24 shware_systems Note Added: 0002523
2015-01-13 10:42 joerg Note Added: 0002524
2015-03-26 16:00 geoffclare Note Added: 0002608
2015-03-26 16:01 geoffclare Interp Status => Pending
2015-03-26 16:01 geoffclare Final Accepted Text => Note: 0002608
2015-03-26 16:01 geoffclare Status New => Interpretation Required
2015-03-26 16:01 geoffclare Resolution Open => Accepted As Marked
2015-03-26 16:02 geoffclare Tag Attached: tc2-2008
2015-03-27 10:55 geoffclare Note Edited: 0002608
2015-04-17 09:52 ajosey Interp Status Pending => Proposed
2015-04-17 09:52 ajosey Note Added: 0002628
2015-05-18 09:06 ajosey Interp Status Proposed => Approved
2015-05-18 09:06 ajosey Note Added: 0002670
2019-06-10 08:54 agadmin Status Interpretation Required => Closed


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