tar or cpio?

[Gary S. Trujillo]

In article <1629 at cuuxb.ATT.COM> mmengel at cuuxb.UUCP (Marc W. Mengel) writes:
| In article <246 at mancol.UUCP> samperi at mancol.UUCP (Dominick Samperi) writes:
| | I've heard that cpio will be used as the unix standard archiver, yet
| | many people seem to prefer tar. 
| | ...
| | I'd be interested to hear about any published standards for tar and/or
| | cpio (AT&T, POSIX, etc.)...
| 
| Well, you missed (about 1 month ago) a LONG discussion (TAR WARS (-:) in
| comp.std.unix, which can be summarized (this off the top of my head, so
| I won't try to credit the appropriate folks) as follows (tar and cpio
| here refer to  their respective archive formats):
| 
|  (deleted Marc's summary)
| 
| These were the points discussed, and the tar format has been chosen (as
| of the last I heard) for the POSIX (a.k.a IEEE 1003) standard.
| 	
| | Dominick Samperi, Manhattan College, NYC
| 
| 
| -- 
|  Marc Mengel	
| 
|  attmail!mmengel
|  ...!{moss|lll-crg|mtune|ihnp4}!cuuxb!mmengel

In reviewing my archives, I came across a copy of a message from the Usenix
Association's representatives to the committee responsible for deciding on
a standard for file interchange via magnetic tape.  I thought readers of this
discussion might find it interesting:

| From husc6!ut-sally!std-unix Wed Aug 26 17:14:10 EDT 1987
| Article 114 of comp.std.unix:
| Path: husc6!ut-sally!std-unix
| From: jsq at usenix.uucp (John Quarterman)
| Newsgroups: comp.std.unix
| Subject: cpio format objections
| Message-ID: <8832 at ut-sally.UUCP> 
| Date: 24 Aug 87 23:24:22 GMT
| Sender: std-unix at ut-sally.UUCP
| Reply-To: jsq at usenix.uucp (John Quarterman)
| Lines: 128
| Approved: fletcher at sally.utexas.edu (Guest Moderator, Fletcher Mattox)
| 
| From: jsq at usenix.uucp (John Quarterman)
| 
| 	  cpio format objections  Page 1 of 2	    IEEE P1003.1 N.117
| 							24 August 1987
| 
| 			       John S. Quarterman
| 
| 		    Institutional Representative from USENIX
| 				   usenix!jsq
| 
| 
| 
| 	  Secretary, IEEE Standards Board
| 	  Attention: P1003 Working Group
| 	  345 East 47th	St.
| 	  New York, NY 10017
| 
| 	  Cc: 1003.1 Technical Reviewers
| 		      for Section 10:		     for Rationale:
| 	  Stephen Dum		    Lorraine Kevra   Hal Jespersen
| 	  tektronix!athena!steved   attunix!kevra    ucbvax!unisoft!hlj
| 
| 	  The USENIX Association ballots no on the test	balloting of
| 	  IEEE 1003.1 Draft 11,	objecting to the proposed inclusion of
| 	  cpio format, for the following reasons:
| 
| 	    1.	The need for extensions	for symbolic links and
| 		contiguous files has not been properly addressed.
| 		Although three type codes are reserved,	no indication
| 		is given of what they should be	used for.  This	does
| 		not promote the	need for those who implement such
| 		extensions to implement	them the same way.  It is true
| 		that the text of the standard cannot refer to symbolic
| 		links or high performance files, because they are not
| 		defined	in the standard.  But the USTAR	format
| 		indicates the use of its codes for those extensions
| 		both by	the name of the	code given in the standard,
| 		and by explicit	recommendations	in the Rationale.  The
| 		cpio proposal does neither.
| 
| 	    2.	The need for implementation-specific extensions	that
| 		do not conflict	with present or	future standard	file
| 		types has not been addressed.  The USTAR format
| 		addresses the problem by reserving 26 codes for
| 		implementations	to use as they see fit.	 The cpio
| 		proposal does not address the problem at all.
| 
| 	    3.	The c_ino field	of the cpio format is derived from the
| 		UNIX inode number.  Many implementations of cpio use
| 		only 16	bits for this number, and thus cannot properly
| 		resolve	links noted in cpio archives that use more
| 		bits for this number.  Tar and USTAR formats do	not
| 		have this problem, because they	do not use a number
| 		like this to resolve links.  While some	USTAR file
| 		types cannot be	read by	historical tar
| 		implementations, an error will usually be produced.
| 		This cpio problem will cause silent creation of
| 
| 
| 
| 
| 
| 
| 
| 	  cpio format objections  Page 2 of 2	    IEEE P1003.1 N.117
| 
| 
| 
| 		erroneous links, which is worse.
| 
| 	    4.	There are few, if any, distributions of	UNIX systems
| 		that do	not include the	tar program, which is
| 		compatible with	the POSIX USTAR	format.	 There are
| 		many UNIX systems that do not include cpio.
| 
| 	    5.	There is a public domain implementation	of USTAR
| 		format.	 There is no public domain implementation of
| 		cpio format, with or without extensions.
| 
| 	  There	should be one data interchange/archive format in IEEE
| 	  1003.1.
| 
| 	     + The proposed cpio format	is technically inferior	to
| 	       USTAR format.
| 
| 	     + The program that	cpio format is based on	is not as
| 	       widely available	as the one that	USTAR format is	based
| 	       on, and the same	is true	of the proposed	cpio format
| 	       and of USTAR format, respectively.
| 
| 	  Therefore, the one format in the standard should be USTAR.
| 
| 	  Specific action:  deny the cpio format proposal, and do not
| 	  include in the standard any references to that format	or to
| 	  cpio.
| 
| 						  Thank	you,
| 
| 
| 
| 						  John S. Quarterman
| 						  Texas	Internet Consulting
| 						  701 Brazos, Suite 500
| 						  Austin, TX 78701-3243
| 						  512-320-9031
| 
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| Volume-Number: Volume 12, Number 21
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Gary S. Trujillo	{ihnp4,harvard,husc6,linus,ima,bbn,m2c}!spdcc!gnosys!gst
Somerville, Massachusetts
-- 
Gary S. Trujillo	{ihnp4,harvard,husc6,linus,ima,bbn,m2c}!spdcc!gnosys!gst
Somerville, Massachusetts