Path: utzoo!mnetor!uunet!husc6!purdue!i.cc.purdue.edu!j.cc.purdue.edu!ain
From: ain@j.cc.purdue.edu (Patrick White)
Newsgroups: comp.sources.amiga
Subject: patch  (docs)
Message-ID: <6615@j.cc.purdue.edu>
Date: 6 Mar 88 07:57:17 GMT
Organization: PUCC Land, USA
Lines: 1060
Approved: ain@j.cc.purdue.edu  (Pat White)

Program Name:	patch  (docs)
Submitted By:	Johan Widen  <jw@sics.se>
Summary:	This is patch ported to the Amiga.
Poster Boy:  Pat White  (ain@j.cc.purdue.edu)

NOTES:
   I've separated this from the origional zoo that it was sent in so we can
post the bin and src separately.. and made the docs a separate shar too.


-- Pat White   (co-moderator comp.sources/binaries.amiga)
UUCP: j.cc.purdue.edu!ain  BITNET: PATWHITE@PURCCVM   PHONE: (317) 743-8421
U.S.  Mail:  320 Brown St. apt. 406,    West Lafayette, IN 47906

========================================

#	This is a shell archive.
#	Remove everything above and including the cut line.
#	Then run the rest of the file through sh.
#----cut here-----cut here-----cut here-----cut here----#
#!/bin/sh
# shar:	Shell Archiver
#	Run the following text with /bin/sh to create:
#	README
#	patch.man.nroffed
#	README.lwall
#	WARNING
#	README.880212
#	MANIFEST
#	patch.man
# This archive created: Sun Mar  6 02:38:00 1988
# By:	Patrick White (PUCC Land, USA)
echo shar: extracting README '(769 characters)'
cat << \SHAR_EOF > README
This is a port of the UNIX patch program to the Amiga.

Patch is an expert at updating source files by applying context diffs to them
(context diffs are produced by the BSD UNIX program diff).

Acknowledgements:
    Larry Wall is the author of patch.
    Peter da Silva is the author of the file requester.
    Matt Dillon has improved the file requester code and is the author of
	newwildcmp.c.
    The files filereq.c and newwildcmp.c are from Matt Dillon's original
    posting of the disk cataloger "files".

Compiling:
    I have only compiled this with the Lattice compiler. Modifications for the
    Manx compiler should be straight forward.

Warning:
    Please read the file 'WARNING' before you use patch.

				23-JAN-88 Johan Widen
					  USENET: jw@sics.se
SHAR_EOF
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then
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fi
echo shar: extracting patch.man.nroffed '(14782 characters)'
cat << \SHAR_EOF > patch.man.nroffed



PATCH(1)            UNIX Programmer's Manual             PATCH(1)



NAME
     patch - a program for applying a diff file to an original

SYNOPSIS
     patch [options] orig patchfile [+ [options] orig]

     but usually just

     patch <patchfile

DESCRIPTION
     _P_a_t_c_h will take a patch file containing any of the three
     forms of difference listing produced by the _d_i_f_f program and
     apply those differences to an original file, producing a
     patched version.  By default, the patched version is put in
     place of the original, with the original file backed up to
     the same name with the extension ".orig", or as specified by
     the -b switch.  You may also specify where you want the out-
     put to go with a -o switch.  If _p_a_t_c_h_f_i_l_e is omitted, or is
     a hyphen, the patch will be read from standard input.

     Upon startup, patch will attempt to determine the type of
     the diff listing, unless over-ruled by a -c, -e, or -n
     switch.  Context diffs and normal diffs are applied by the
     _p_a_t_c_h program itself, while ed diffs are simply fed to the
     _e_d editor via a pipe.

     _P_a_t_c_h will try to skip any leading garbage, apply the diff,
     and then skip any trailing garbage.  Thus you could feed an
     article or message containing a diff listing to _p_a_t_c_h, and
     it should work.  If the entire diff is indented by a con-
     sistent amount, this will be taken into account.

     With context diffs, and to a lesser extent with normal
     diffs, _p_a_t_c_h can detect when the line numbers mentioned in
     the patch are incorrect, and will attempt to find the
     correct place to apply each hunk of the patch.  As a first
     guess, it takes the line number mentioned for the hunk, plus
     or minus any offset used in applying the previous hunk.  If
     that is not the correct place, _p_a_t_c_h will scan both forwards
     and backwards for a set of lines matching the context given
     in the hunk.  First _p_a_t_c_h looks for a place where all lines
     of the context match.  If no such place is found, and it's a
     context diff, and the maximum fuzz factor is set to 1 or
     more, then another scan takes place ignoring the first and
     last line of context.  If that fails, and the maximum fuzz
     factor is set to 2 or more, the first two and last two lines
     of context are ignored, and another scan is made.  (The
     default maximum fuzz factor is 2.) If _p_a_t_c_h cannot find a
     place to install that hunk of the patch, it will put the
     hunk out to a reject file, which normally is the name of the
     output file plus ".rej".  (Note that the rejected hunk will



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     come out in context diff form whether the input patch was a
     context diff or a normal diff.  If the input was a normal
     diff, many of the contexts will simply be null.) The line
     numbers on the hunks in the reject file may be different
     than in the patch file: they reflect the approximate loca-
     tion patch thinks the failed hunks belong in the new file
     rather than the old one.

     As each hunk is completed, you will be told whether the hunk
     succeeded or failed, and which line (in the new file) _p_a_t_c_h
     thought the hunk should go on.  If this is different from
     the line number specified in the diff you will be told the
     offset.  A single large offset MAY be an indication that a
     hunk was installed in the wrong place.  You will also be
     told if a fuzz factor was used to make the match, in which
     case you should also be slightly suspicious.

     If no original file is specified on the command line, _p_a_t_c_h
     will try to figure out from the leading garbage what the
     name of the file to edit is.  In the header of a context
     diff, the filename is found from lines beginning with "***"
     or "---", with the shortest name of an existing file win-
     ning.  Only context diffs have lines like that, but if there
     is an "Index:" line in the leading garbage, _p_a_t_c_h will try
     to use the filename from that line.  The context diff header
     takes precedence over an Index line.  If no filename can be
     intuited from the leading garbage, you will be asked for the
     name of the file to patch.

     (If the original file cannot be found, but a suitable SCCS
     or RCS file is handy, _p_a_t_c_h will attempt to get or check out
     the file.)

     Additionally, if the leading garbage contains a "Prereq: "
     line, _p_a_t_c_h will take the first word from the prerequisites
     line (normally a version number) and check the input file to
     see if that word can be found.  If not, _p_a_t_c_h will ask for
     confirmation before proceeding.

     The upshot of all this is that you should be able to say,
     while in a news interface, the following:

          | patch -d /usr/src/local/blurfl

     and patch a file in the blurfl directory directly from the
     article containing the patch.

     If the patch file contains more than one patch, _p_a_t_c_h will
     try to apply each of them as if they came from separate
     patch files.  This means, among other things, that it is
     assumed that the name of the file to patch must be deter-
     mined for each diff listing, and that the garbage before



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     each diff listing will be examined for interesting things
     such as filenames and revision level, as mentioned previ-
     ously.  You can give switches (and another original file
     name) for the second and subsequent patches by separating
     the corresponding argument lists by a '+'.  (The argument
     list for a second or subsequent patch may not specify a new
     patch file, however.)

     _P_a_t_c_h recognizes the following switches:

     -b   causes the next argument to be interpreted as the
          backup extension, to be used in place of ".orig".

     -c   forces _p_a_t_c_h to interpret the patch file as a context
          diff.

     -d   causes _p_a_t_c_h to interpret the next argument as a direc-
          tory, and cd to it before doing anything else.

     -D   causes _p_a_t_c_h to use the "#ifdef...#endif" construct to
          mark changes.  The argument following will be used as
          the differentiating symbol.  Note that, unlike the C
          compiler, there must be a space between the -D and the
          argument.

     -e   forces _p_a_t_c_h to interpret the patch file as an ed
          script.

     -f   forces _p_a_t_c_h to assume that the user knows exactly what
          he or she is doing, and to not ask any questions.  It
          does not suppress commentary, however.  Use -s for
          that.

     -F<number>
          sets the maximum fuzz factor.  This switch only applied
          to context diffs, and causes _p_a_t_c_h to ignore up to that
          many lines in looking for places to install a hunk.
          Note that a larger fuzz factor increases the odds of a
          faulty patch.  The default fuzz factor is 2, and it may
          not be set to more than the number of lines of context
          in the context diff, ordinarily 3.

     -l   causes the pattern matching to be done loosely, in case
          the tabs and spaces have been munged in your input
          file.  Any sequence of whitespace in the pattern line
          will match any sequence in the input file.  Normal
          characters must still match exactly.  Each line of the
          context must still match a line in the input file.

     -n   forces _p_a_t_c_h to interpret the patch file as a normal
          diff.




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     -N   causes _p_a_t_c_h to ignore patches that it thinks are
          reversed or already applied.  See also -R .

     -o   causes the next argument to be interpreted as the out-
          put file name.

     -p<number>
          sets the pathname strip count, which controls how path-
          names found in the patch file are treated, in case the
          you keep your files in a different directory than the
          person who sent out the patch.  The strip count speci-
          fies how many backslashes are to be stripped from the
          front of the pathname.  (Any intervening directory
          names also go away.) For example, supposing the
          filename in the patch file was

               /u/howard/src/blurfl/blurfl.c

          setting -p or -p0 gives the entire pathname unmodified,
          -p1 gives

               u/howard/src/blurfl/blurfl.c

          without the leading slash, -p4 gives

               blurfl/blurfl.c

          and not specifying -p at all just gives you "blurfl.c".
          Whatever you end up with is looked for either in the
          current directory, or the directory specified by the -d
          switch.

     -r   causes the next argument to be interpreted as the
          reject file name.

     -R   tells _p_a_t_c_h that this patch was created with the old
          and new files swapped.  (Yes, I'm afraid that does hap-
          pen occasionally, human nature being what it is.) _P_a_t_c_h
          will attempt to swap each hunk around before applying
          it.  Rejects will come out in the swapped format.  The
          -R switch will not work with ed diff scripts because
          there is too little information to reconstruct the
          reverse operation.

          If the first hunk of a patch fails, _p_a_t_c_h will reverse
          the hunk to see if it can be applied that way.  If it
          can, you will be asked if you want to have the -R
          switch set.  If it can't, the patch will continue to be
          applied normally.  (Note: this method cannot detect a
          reversed patch if it is a normal diff and if the first
          command is an append (i.e. it should have been a
          delete) since appends always succeed, due to the fact



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          that a null context will match anywhere.  Luckily, most
          patches add or change lines rather than delete them, so
          most reversed normal diffs will begin with a delete,
          which will fail, triggering the heuristic.)

     -s   makes _p_a_t_c_h do its work silently, unless an error
          occurs.

     -S   causes _p_a_t_c_h to ignore this patch from the patch file,
          but continue on looking for the next patch in the file.
          Thus

               patch -S + -S + <patchfile

          will ignore the first and second of three patches.

     -v   causes _p_a_t_c_h to print out it's revision header and
          patch level.

     -x<number>
          sets internal debugging flags, and is of interest only
          to _p_a_t_c_h patchers.

ENVIRONMENT
     No environment variables are used by _p_a_t_c_h.

FILES
     /tmp/patch*

SEE ALSO
     diff(1)

NOTES FOR PATCH SENDERS
     There are several things you should bear in mind if you are
     going to be sending out patches.  First, you can save people
     a lot of grief by keeping a patchlevel.h file which is
     patched to increment the patch level as the first diff in
     the patch file you send out.  If you put a Prereq: line in
     with the patch, it won't let them apply patches out of order
     without some warning.  Second, make sure you've specified
     the filenames right, either in a context diff header, or
     with an Index: line.  If you are patching something in a
     subdirectory, be sure to tell the patch user to specify a -p
     switch as needed.  Third, you can create a file by sending
     out a diff that compares a null file to the file you want to
     create.  This will only work if the file you want to create
     doesn't exist already in the target directory.  Fourth, take
     care not to send out reversed patches, since it makes people
     wonder whether they already applied the patch.  Fifth, while
     you may be able to get away with putting 582 diff listings
     into one file, it is probably wiser to group related patches
     into separate files in case something goes haywire.



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DIAGNOSTICS
     Too many to list here, but generally indicative that _p_a_t_c_h
     couldn't parse your patch file.

     The message "Hmm..." indicates that there is unprocessed
     text in the patch file and that _p_a_t_c_h is attempting to
     intuit whether there is a patch in that text and, if so,
     what kind of patch it is.

CAVEATS
     _P_a_t_c_h cannot tell if the line numbers are off in an ed
     script, and can only detect bad line numbers in a normal
     diff when it finds a "change" or a "delete" command.  A con-
     text diff using fuzz factor 3 may have the same problem.
     Until a suitable interactive interface is added, you should
     probably do a context diff in these cases to see if the
     changes made sense.  Of course, compiling without errors is
     a pretty good indication that the patch worked, but not
     always.

     _P_a_t_c_h usually produces the correct results, even when it has
     to do a lot of guessing.  However, the results are
     guaranteed to be correct only when the patch is applied to
     exactly the same version of the file that the patch was gen-
     erated from.

BUGS
     Could be smarter about partial matches, excessively deviant
     offsets and swapped code, but that would take an extra pass.

     If code has been duplicated (for instance with #ifdef OLD-
     CODE ... #else ...  #endif), _p_a_t_c_h is incapable of patching
     both versions, and, if it works at all, will likely patch
     the wrong one, and tell you that it succeeded to boot.

     If you apply a patch you've already applied, _p_a_t_c_h will
     think it is a reversed patch, and offer to un-apply the
     patch.  This could be construed as a feature.

















Printed 3/6/88                LOCAL                             6



SHAR_EOF
if test 14782 -ne "`wc -c patch.man.nroffed`"
then
echo shar: error transmitting patch.man.nroffed '(should have been 14782 characters)'
fi
echo shar: extracting README.lwall '(2963 characters)'
cat << \SHAR_EOF > README.lwall
			Patch Kit, Version 2.0

		    Copyright (c) 1986, Larry Wall

You may copy the patch kit in whole or in part as long as you don't try to
make money off it, or pretend that you wrote it.
--------------------------------------------------------------------------

Please read all the directions below before you proceed any further, and
then follow them carefully.  Failure to do so may void your warranty. :-)

After you have unpacked your kit, you should have all the files listed
in MANIFEST.

Installation

1)  Run Configure.  This will figure out various things about your system.
    Some things Configure will figure out for itself, other things it will
    ask you about.  It will then proceed to make config.h, config.sh, and
    Makefile.

    You might possibly have to trim # comments from the front of Configure
    if your sh doesn't handle them, but all other # comments will be taken
    care of.

    If you don't have sh, you'll have to rip the prototype of config.h out
    of Configure and generate the defines by hand.

2)  Glance through config.h to make sure system dependencies are correct.
    Most of them should have been taken care of by running the Configure script.

    If you have any additional changes to make to the C definitions, they
    can be done in the Makefile, or in config.h.  Bear in mind that they may
    get undone next time you run Configure.

3)  make

    This will attempt to make patch in the current directory.

4)  make install

    This will put patch into a public directory (normally /usr/local/bin).
    It will also try to put the man pages in a reasonable place.  It will not
    nroff the man page, however.

5)  Read the manual entry before running patch.

6)  IMPORTANT!  Help save the world!  Communicate any problems and
    suggested patches to me, lwall@sdcrdcf.UUCP (Larry Wall), so we can
    keep the world in sync.  If you have a problem, there's someone else
    out there who either has had or will have the same problem.

    If possible, send in patches such that the patch program will apply them.
    Context diffs are the best, then normal diffs.  Don't send ed scripts--
    I've probably changed my copy since the version you have.

    Watch for patch patches in net.sources.bugs.  Patches will generally be
    in a form usable by the patch program.  If you are just now bringing up
    patch and aren't sure how many patches there are, write to me and I'll
    send any you don't have.  Your current patch level is shown in patchlevel.h.


NEW FEATURES IN THIS RELEASE

(Correct) support for 4.3bsd-style context diffs.
Files can be created from scratch.
You can specify a fuzz-factor for context matching.
You can force patch to ask no questions.
You can specify how much of the leading pathname to strip off filenames.
Uses a Configure script for greater portability.
You are now asked if you want to apply a reversed patch.
No limit (apart from memory) on the size of hunks.
SHAR_EOF
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then
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fi
echo shar: extracting WARNING '(426 characters)'
cat << \SHAR_EOF > WARNING
WARNING: This program may destroy your files.

The business of patch is to update source files. Bugs may have been introduced
when patch was ported to the Amiga.  Although I am not aware of any dangerous
bugs at present, they may well be there! Always backup your files before you
apply patch to them.

I disclaim any responsibility for damages caused by the use of patch.

				23-JAN-88 Johan Widen
					  USENET: jw@sics.se
SHAR_EOF
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then
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fi
echo shar: extracting README.880212 '(160 characters)'
cat << \SHAR_EOF > README.880212
12-FEB-88

The following diffs fix a moderately serious bug in patch for the Amiga.
Patch did not remove all file locks.

				Johan Widen
			USENET: jw@sics.se
SHAR_EOF
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then
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fi
echo shar: extracting MANIFEST '(204 characters)'
cat << \SHAR_EOF > MANIFEST
MANIFEST
README
WARNING
README.lwall
patch.man
Makefile
EXTERN.h
INTERN.h
common.h
config.h
filereq.c
inp.c
inp.h
newwildcmp.c
patch.c
patchlevel.h
pch.c
pch.h
request.c
util.c
util.h
version.c
version.h
SHAR_EOF
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then
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fi
echo shar: extracting patch.man '(13700 characters)'
cat << \SHAR_EOF > patch.man
''' $Header: patch.man,v 2.0 86/09/17 15:39:09 lwall Exp $
''' 
''' $Log:	patch.man,v $
''' Revision 2.0  86/09/17  15:39:09  lwall
''' Baseline for netwide release.
''' 
''' Revision 1.4  86/08/01  19:23:22  lwall
''' Documented -v, -p, -F.
''' Added notes to patch senders.
''' 
''' Revision 1.3  85/03/26  15:11:06  lwall
''' Frozen.
''' 
''' Revision 1.2.1.4  85/03/12  16:14:27  lwall
''' Documented -p.
''' 
''' Revision 1.2.1.3  85/03/12  16:09:41  lwall
''' Documented -D.
''' 
''' Revision 1.2.1.2  84/12/05  11:06:55  lwall
''' Added -l switch, and noted bistability bug.
''' 
''' Revision 1.2.1.1  84/12/04  17:23:39  lwall
''' Branch for sdcrdcf changes.
''' 
''' Revision 1.2  84/12/04  17:22:02  lwall
''' Baseline version.
''' 
.de Sh
.br
.ne 5
.PP
\fB\\$1\fR
.PP
..
.de Sp
.if t .sp .5v
.if n .sp
..
'''
'''     Set up \*(-- to give an unbreakable dash;
'''     string Tr holds user defined translation string.
'''     Bell System Logo is used as a dummy character.
'''
.ie n \{\
.tr \(bs-\*(Tr
.ds -- \(bs-
.if (\n(.H=4u)&(1m=24u) .ds -- \(bs\h'-12u'\(bs\h'-12u'-\" diablo 10 pitch
.if (\n(.H=4u)&(1m=20u) .ds -- \(bs\h'-12u'\(bs\h'-8u'-\" diablo 12 pitch
.ds L" ""
.ds R" ""
.ds L' '
.ds R' '
'br\}
.el\{\
.ds -- \(em\|
.tr \*(Tr
.ds L" ``
.ds R" ''
.ds L' `
.ds R' '
'br\}
.TH PATCH 1 LOCAL
.SH NAME
patch - a program for applying a diff file to an original
.SH SYNOPSIS
.B patch
[options] orig patchfile [+ [options] orig]
.sp
but usually just
.sp
.B patch
<patchfile
.SH DESCRIPTION
.I Patch
will take a patch file containing any of the three forms of difference
listing produced by the
.I diff
program and apply those differences to an original file, producing a patched
version.
By default, the patched version is put in place of the original, with
the original file backed up to the same name with the
extension \*(L".orig\*(R", or as specified by the
.B -b
switch.
You may also specify where you want the output to go with a
.B -o
switch.
If
.I patchfile
is omitted, or is a hyphen, the patch will be read from standard input.
.PP
Upon startup, patch will attempt to determine the type of the diff listing,
unless over-ruled by a
.BR -c ,
.BR -e ,
or
.B -n
switch.
Context diffs and normal diffs are applied by the
.I patch
program itself, while ed diffs are simply fed to the
.I ed
editor via a pipe.
.PP
.I Patch
will try to skip any leading garbage, apply the diff,
and then skip any trailing garbage.
Thus you could feed an article or message containing a
diff listing to
.IR patch ,
and it should work.
If the entire diff is indented by a consistent amount,
this will be taken into account.
.PP
With context diffs, and to a lesser extent with normal diffs,
.I patch
can detect when the line numbers mentioned in the patch are incorrect,
and will attempt to find the correct place to apply each hunk of the patch.
As a first guess, it takes the line number mentioned for the hunk, plus or
minus any offset used in applying the previous hunk.
If that is not the correct place,
.I patch
will scan both forwards and backwards for a set of lines matching the context
given in the hunk.
First
.I patch
looks for a place where all lines of the context match.
If no such place is found, and it's a context diff, and the maximum fuzz factor
is set to 1 or more, then another scan takes place ignoring the first and last
line of context.
If that fails, and the maximum fuzz factor is set to 2 or more,
the first two and last two lines of context are ignored,
and another scan is made.
(The default maximum fuzz factor is 2.)
If
.I patch
cannot find a place to install that hunk of the patch, it will put the
hunk out to a reject file, which normally is the name of the output file
plus \*(L".rej\*(R".
(Note that the rejected hunk will come out in context diff form whether the
input patch was a context diff or a normal diff.
If the input was a normal diff, many of the contexts will simply be null.)
The line numbers on the hunks in the reject file may be different than
in the patch file: they reflect the approximate location patch thinks the
failed hunks belong in the new file rather than the old one.
.PP
As each hunk is completed, you will be told whether the hunk succeeded or
failed, and which line (in the new file)
.I patch
thought the hunk should go on.
If this is different from the line number specified in the diff you will
be told the offset.
A single large offset MAY be an indication that a hunk was installed in the
wrong place.
You will also be told if a fuzz factor was used to make the match, in which
case you should also be slightly suspicious.
.PP
If no original file is specified on the command line,
.I patch
will try to figure out from the leading garbage what the name of the file
to edit is.
In the header of a context diff, the filename is found from lines beginning
with \*(L"***\*(R" or \*(L"---\*(R", with the shortest name of an existing
file winning.
Only context diffs have lines like that, but if there is an \*(L"Index:\*(R"
line in the leading garbage,
.I patch
will try to use the filename from that line.
The context diff header takes precedence over an Index line.
If no filename can be intuited from the leading garbage, you will be asked
for the name of the file to patch.
.PP
(If the original file cannot be found, but a suitable SCCS or RCS file is
handy,
.I patch
will attempt to get or check out the file.)
.PP
Additionally, if the leading garbage contains a \*(L"Prereq: \*(R" line,
.I patch
will take the first word from the prerequisites line (normally a version
number) and check the input file to see if that word can be found.
If not,
.I patch
will ask for confirmation before proceeding.
.PP
The upshot of all this is that you should be able to say, while in a news
interface, the following:
.Sp
	| patch -d /usr/src/local/blurfl
.Sp
and patch a file in the blurfl directory directly from the article containing
the patch.
.PP
If the patch file contains more than one patch,
.I patch
will try to apply each of them as if they came from separate patch files.
This means, among other things, that it is assumed that the name of the file
to patch must be determined for each diff listing,
and that the garbage before each diff listing will
be examined for interesting things such as filenames and revision level, as
mentioned previously.
You can give switches (and another original file name) for the second and
subsequent patches by separating the corresponding argument lists
by a \*(L'+\*(R'.
(The argument list for a second or subsequent patch may not specify a new
patch file, however.)
.PP
.I Patch
recognizes the following switches:
.TP 5
.B \-b
causes the next argument to be interpreted as the backup extension, to be
used in place of \*(L".orig\*(R".
.TP 5
.B \-c
forces
.I patch
to interpret the patch file as a context diff.
.TP 5
.B \-d
causes
.I patch
to interpret the next argument as a directory, and cd to it before doing
anything else.
.TP 5
.B \-D
causes
.I patch
to use the "#ifdef...#endif" construct to mark changes.
The argument following will be used as the differentiating symbol.
Note that, unlike the C compiler, there must be a space between the
.B \-D
and the argument.
.TP 5
.B \-e
forces
.I patch
to interpret the patch file as an ed script.
.TP 5
.B \-f
forces
.I patch
to assume that the user knows exactly what he or she is doing, and to not
ask any questions.
It does not suppress commentary, however.
Use
.B \-s
for that.
.TP 5
.B \-F<number>
sets the maximum fuzz factor.
This switch only applied to context diffs, and causes
.I patch
to ignore up to that many lines in looking for places to install a hunk.
Note that a larger fuzz factor increases the odds of a faulty patch.
The default fuzz factor is 2, and it may not be set to more than
the number of lines of context in the context diff, ordinarily 3.
.TP 5
.B \-l
causes the pattern matching to be done loosely, in case the tabs and
spaces have been munged in your input file.
Any sequence of whitespace in the pattern line will match any sequence
in the input file.
Normal characters must still match exactly.
Each line of the context must still match a line in the input file.
.TP 5
.B \-n
forces
.I patch
to interpret the patch file as a normal diff.
.TP 5
.B \-N
causes
.I patch
to ignore patches that it thinks are reversed or already applied.
See also
.B \-R .
.TP 5
.B \-o
causes the next argument to be interpreted as the output file name.
.TP 5
.B \-p<number>
sets the pathname strip count,
which controls how pathnames found in the patch file are treated, in case
the you keep your files in a different directory than the person who sent
out the patch.
The strip count specifies how many backslashes are to be stripped from
the front of the pathname.
(Any intervening directory names also go away.)
For example, supposing the filename in the patch file was
.sp
	/u/howard/src/blurfl/blurfl.c
.sp
setting
.B \-p
or
.B \-p0
gives the entire pathname unmodified,
.B \-p1
gives
.sp
	u/howard/src/blurfl/blurfl.c
.sp
without the leading slash,
.B \-p4
gives
.sp
	blurfl/blurfl.c
.sp
and not specifying
.B \-p
at all just gives you "blurfl.c".
Whatever you end up with is looked for either in the current directory,
or the directory specified by the
.B \-d
switch.
.TP 5
.B \-r
causes the next argument to be interpreted as the reject file name.
.TP 5
.B \-R
tells
.I patch
that this patch was created with the old and new files swapped.
(Yes, I'm afraid that does happen occasionally, human nature being what it
is.)
.I Patch
will attempt to swap each hunk around before applying it.
Rejects will come out in the swapped format.
The
.B \-R
switch will not work with ed diff scripts because there is too little
information to reconstruct the reverse operation.
.Sp
If the first hunk of a patch fails,
.I patch
will reverse the hunk to see if it can be applied that way.
If it can, you will be asked if you want to have the
.B \-R
switch set.
If it can't, the patch will continue to be applied normally.
(Note: this method cannot detect a reversed patch if it is a normal diff
and if the first command is an append (i.e. it should have been a delete)
since appends always succeed, due to the fact that a null context will match
anywhere.
Luckily, most patches add or change lines rather than delete them, so most
reversed normal diffs will begin with a delete, which will fail, triggering
the heuristic.)
.TP 5
.B \-s
makes
.I patch
do its work silently, unless an error occurs.
.TP 5
.B \-S
causes
.I patch
to ignore this patch from the patch file, but continue on looking
for the next patch in the file.
Thus
.sp
	patch -S + -S + <patchfile
.sp
will ignore the first and second of three patches.
.TP 5
.B \-v
causes
.I patch
to print out it's revision header and patch level.
.TP 5
.B \-x<number>
sets internal debugging flags, and is of interest only to
.I patch
patchers.
.SH ENVIRONMENT
No environment variables are used by
.IR patch .
.SH FILES
/tmp/patch*
.SH SEE ALSO
diff(1)
.SH NOTES FOR PATCH SENDERS
There are several things you should bear in mind if you are going to
be sending out patches.
First, you can save people a lot of grief by keeping a patchlevel.h file
which is patched to increment the patch level as the first diff in the
patch file you send out.
If you put a Prereq: line in with the patch, it won't let them apply
patches out of order without some warning.
Second, make sure you've specified the filenames right, either in a
context diff header, or with an Index: line.
If you are patching something in a subdirectory, be sure to tell the patch
user to specify a 
.B \-p
switch as needed.
Third, you can create a file by sending out a diff that compares a
null file to the file you want to create.
This will only work if the file you want to create doesn't exist already in
the target directory.
Fourth, take care not to send out reversed patches, since it makes people wonder
whether they already applied the patch.
Fifth, while you may be able to get away with putting 582 diff listings into
one file, it is probably wiser to group related patches into separate files in
case something goes haywire.
.SH DIAGNOSTICS
Too many to list here, but generally indicative that
.I patch
couldn't parse your patch file.
.PP
The message \*(L"Hmm...\*(R" indicates that there is unprocessed text in
the patch file and that
.I patch
is attempting to intuit whether there is a patch in that text and, if so,
what kind of patch it is.
.SH CAVEATS
.I Patch
cannot tell if the line numbers are off in an ed script, and can only detect
bad line numbers in a normal diff when it finds a \*(L"change\*(R" or
a \*(L"delete\*(R" command.
A context diff using fuzz factor 3 may have the same problem.
Until a suitable interactive interface is added, you should probably do
a context diff in these cases to see if the changes made sense.
Of course, compiling without errors is a pretty good indication that the patch
worked, but not always.
.PP
.I Patch
usually produces the correct results, even when it has to do a lot of
guessing.
However, the results are guaranteed to be correct only when the patch is
applied to exactly the same version of the file that the patch was
generated from.
.SH BUGS
Could be smarter about partial matches, excessively \&deviant offsets and
swapped code, but that would take an extra pass.
.PP
If code has been duplicated (for instance with #ifdef OLDCODE ... #else ...
#endif),
.I patch
is incapable of patching both versions, and, if it works at all, will likely
patch the wrong one, and tell you that it succeeded to boot.
.PP
If you apply a patch you've already applied,
.I patch
will think it is a reversed patch, and offer to un-apply the patch.
This could be construed as a feature.
SHAR_EOF
if test 13700 -ne "`wc -c patch.man`"
then
echo shar: error transmitting patch.man '(should have been 13700 characters)'
fi
#	End of shell archive
exit 0