Date: Mon, 12 Jan 1998 18:56:20 -0500 (EST) From: woods@most.weird.com (Greg A. Woods) To: Joerg Wunsch <joerg_wunsch@uriah.heep.sax.de> Cc: =?iso-8859-1?Q?=E1=CE=C4=D2=C5=CA_=FE=C5=D2=CE=CF=D7?= <ache@nagual.pp.ru>, Peter Wemm <peter@netplex.com.au>, FreeBSD-current <current@freebsd.org>, info-cvs@gnu.org Subject: Re: CVS DIFF fix for review (-L added) Message-ID: <m0xrtiO-00077aC@most.weird.com> In-Reply-To: J. Wunsch's message of "Mon, January 12, 1998 08:20:22 %2B0100" regarding "Re: CVS DIFF fix for review (-L added)" id <19980112082022.30571@uriah.heep.sax.de> References: <199801111457.WAA06475@spinner.netplex.com.au> <Pine.BSF.3.96.980111232840.17312A-100000@lsd.relcom.eu.net> <19980112082022.30571@uriah.heep.sax.de>
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[ On Mon, January 12, 1998 at 08:20:22 (+0100), J. Wunsch wrote: ]
> Subject: Re: CVS DIFF fix for review (-L added)
>
> The idea of Index: was great, but there has never been a patch utility
> supporting it the way CVS did expect. :-O Again, all the pre-existant
> ``support'' for Index: lines taking precedence over context-diff
> headers was _incidentally_.
Oh, I beg to differ! It was upon my request that "Index:" was
originally added to the `cvs diff' output, specifically to support
patch. I think even the last release of patch by Larry Wall contained
support for "Index:". However versions of GNU Patch since 2.3.7 have
only supported the "Index:" tag when requested by setting the
environment variable POSIXLY_CORRECT (or completely omitting filenames
in the context header) [see note rule 2]. This from 2.4's manual:
If no original file origfile is specified on the command
line, patch tries to figure out from the leading garbage
what the name of the file to edit is, using the following
rules.
+ If the header is that of a context diff, patch takes the
old and new file names in the header. Any /dev/null
names are ignored.
+ If there is an Index: line in the leading garbage and if
either the old and new names are both absent or the
POSIXLY_CORRECT environment variable is set, patch takes
the name in the Index: line.
+ For the purpose of the following rules, the names are
considered to be in the order (old, new, index), regard-
less of the order that they appear in the header.
+ If some of the named files exist, patch uses the first
name if the POSIXLY_CORRECT environment variable is set,
and the best name otherwise.
+ If patch is not ignoring RCS and SCCS (see the -g num or
--get=num option), and no named files exist but an RCS or
SCCS master is found, patch uses the first named file
with an RCS or SCCS master.
+ If no named files exist, no RCS or SCCS master was found,
some names are given, POSIXLY_CORRECT is not set, and the
patch appears to create a file, patch uses the best name
requiring the creation of the fewest directories.
Unfortunately POSIX has made life difficult yet again (rule three seems
to make the "Index:" header have the least precedence even when it would
be more logical to have it the most precedence).... At least now it's
all documented and "standard".
--
Greg A. Woods
+1 416 443-1734 VE3TCP <gwoods@acm.org> <robohack!woods>
Planix, Inc. <woods@planix.com>; Secrets of the Weird <woods@weird.com>
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