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Last update: 20 April,2001

								1003.2-92  #08

	Class: No change.

This response will be incorporated in an IEEE interpretations
publication, and will be also made available on-line on the IEEE 
SPAsystem.

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	Interpretation Number:	(to be assigned by the IEEE)
	Topic:			sort
	Relevant Sections:	2.9.1.4


Interpretation Request: (Defect Report)
-----------------------
 
          In Section 2.9.1.4 - File Read,  Write,  and  Creation,  the 
          standard states that: 
 
               When an attempt is made  to  create  a  file  that 
               already exists, the action  shall  depend  on  the 
               file type: 
 
                    (1)  For directories and FIFO special  files, 
                         the attempt shall fail and  the  utility 
                         shall either continue with its operation 
                         or  exit  immediately  with  a   nonzero 
                         status, depending on the description  of 
                         the utility. 
 
          [Draft 12 of IEEE Std 1003.2-1992 (July 1992), p. 96,  lines 
          3433-3437] 
 
          Does the standard really mean  what  it  says?   Will  every 
          utility that creates an output file need to first check that 
          there is not a file of type FIFO with that  name  before  it 
          open()s it for writing? 
 
          If so, ``mkfifo foo; sort -o foo  file''  will  fail.  Being 
          able to use a FIFO as  a  pipe  with  a  name  is  a  useful 
          behaviour.  It  allows  applications  to  connect  utilities 
          together in more complex ways than simple pipelines. 
 

IEEE Interpretation for 1003.2-1992 
-----------------------------------


The quoted text from Section 2.9.1.4 is modified by Section 2.9.1, lines
3360-3361 "Utility and function description statements override these
defaults when appropriate."

The sort -o option is described in the Output Files section as "If the
-o option is in effect, the sorted output shall be placed in the
file..". This overrides section 2.9.1.4, requiring that the output be
placed in the file, as it does not speak of requiring creation of said
file.

Rationale for Interpretation:
-----------------------------
None.
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