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PATCH(1)							      PATCH(1)

NAME
       patch - apply a diff file to an original

SYNOPSIS
       patch [options] [originalfile [patchfile]]

       but usually just

       patch -pnum <patchfile

DESCRIPTION
       patch takes a patch file	patchfile containing a difference listing pro-
       duced by	the diff program and applies those differences to one or  more
       original	 files,	producing patched versions.  Normally the patched ver-
       sions are put in	place of the originals.	 Backups can be	made; see  the
       -b  or  --backup	option.	 The names of the files	to be patched are usu-
       ally taken from the patch file, but if there's  just  one  file	to  be
       patched it can specified	on the command line as originalfile.

       Upon startup, patch attempts to determine the type of the diff listing,
       unless overruled	by a -c	(--context), -e	(--ed),	-n (--normal),	or  -u
       (--unified)  option.  Context diffs (old-style, new-style, and unified)
       and normal diffs	are applied by the  patch  program  itself,  while  ed
       diffs are simply	fed to the ed(1) editor	via a pipe.

       patch  tries to skip any	leading	garbage, apply the diff, and then skip
       any trailing garbage.  Thus you could feed an article or	 message  con-
       taining	a  diff	 listing  to patch, and	it should work.	 If the	entire
       diff is indented	by a consistent	amount,	or if a	context	diff  contains
       lines ending in CRLF or is encapsulated one or more times by prepending
       "- " to lines starting with "-" as specified by Internet	RFC 934,  this
       is taken	into account.

       With context diffs, and to a lesser extent with normal diffs, patch can
       detect when the line numbers mentioned in the patch are incorrect,  and
       attempts	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, patch	scans both forwards and	backwards for a	set of
       lines  matching the context given in the	hunk.  First 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
       patch cannot find a place to install that hunk of the  patch,  it  puts
       the hunk	out to a reject	file, which normally is	the name of the	output
       file plus a .rej	suffix,	or # if	.rej would generate a file  name  that
       is  too	long  (if even appending the single character #	makes the file
       name too	long, then # replaces the file name's last  character).	  (The
       rejected	hunk comes out in ordinary context diff	form regardless	of the
       input patch's form.  If the input was a normal diff, many of  the  con-
       texts  are  simply  null.)  The line numbers on the hunks in the	reject
       file may	be different than in the patch file: they reflect the approxi-
       mate  location  patch  thinks  the  failed hunks	belong in the new file
       rather than the old one.

       As each hunk is completed, you are told if the hunk failed, and	if  so
       which  line  (in	the new	file) patch thought the	hunk should go on.  If
       the hunk	is installed at	a different line from the line	number	speci-
       fied  in	 the  diff you are told	the offset.  A single large offset may
       indicate	that a hunk was	installed in the wrong place.	You  are  also
       told  if	 a  fuzz  factor was used to make the match, in	which case you
       should also be slightly suspicious.  If the --verbose option is	given,
       you are also told about hunks that match	exactly.

       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.

       First, patch takes an ordered list of candidate file names as follows:

	+o If the header	is that	of a context diff, patch takes the old and new
	  file names in	the header.  A name is ignored if  it  does  not  have
	  enough slashes to satisfy the	-pnum or --strip=num option.  The name
	  /dev/null is also ignored.

	+o If there is an Index:	line in	the leading garbage and	if either  the
	  old  and  new	 names	are  both  absent or if	patch is conforming to
	  POSIX, patch takes the name in the Index: line.

	+o For the purpose of the following rules, the candidate	file names are
	  considered  to  be in	the order (old,	new, index), regardless	of the
	  order	that they appear in the	header.

       Then patch selects a file name from the candidate list as follows:

	+o If some of the named files exist, patch selects the  first  name  if
	  conforming to	POSIX, and the best name otherwise.

	+o If patch is not ignoring RCS,	ClearCase, and SCCS (see the -g	num or
	  --get=num option), and no named files	exist but an  RCS,  ClearCase,
	  or  SCCS master is found, patch selects the first named file with an
	  RCS, ClearCase, or SCCS master.

	+o If no	named files exist, no  RCS,  ClearCase,	 or  SCCS  master  was
	  found,  some	names are given, patch is not conforming to POSIX, and
	  the patch appears to create a	file,  patch  selects  the  best  name
	  requiring the	creation of the	fewest directories.

	+o If no	file name results from the above heuristics, you are asked for
	  the name of the file to patch, and patch selects that	name.

       To determine the	best of	a nonempty list	of  file  names,  patch	 first
       takes  all the names with the fewest path name components; of those, it
       then takes all the names	with the shortest basename; of those, it  then
       takes  all  the	shortest  names; finally, it takes the first remaining
       name.

       Additionally, if	the leading garbage contains  a	 Prereq:  line,	 patch
       takes  the  first  word from the	prerequisites line (normally a version
       number) and checks the original file to see if that word	can be	found.
       If not, patch asks for confirmation before proceeding.

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

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

       and patch a file	in the blurfl directory	directly from the article con-
       taining the patch.

       If  the	patch  file contains more than one patch, patch	tries 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	contains interesting things such as file names
       and revision level, as mentioned	previously.

OPTIONS
       -b  or  --backup
	  Make backup files.  That is, when patching a file,  rename  or  copy
	  the  original	 instead  of removing it.  When	backing	up a file that
	  does not exist, an empty, unreadable backup file  is	created	 as  a
	  placeholder to represent the nonexistent file.  See the -V or	--ver-
	  sion-control option for details about	 how  backup  file  names  are
	  determined.

       --backup-if-mismatch
	  Back	up  a file if the patch	does not match the file	exactly	and if
	  backups are not otherwise requested.	This  is  the  default	unless
	  patch	is conforming to POSIX.

       --no-backup-if-mismatch
	  Do  not  back	up a file if the patch does not	match the file exactly
	  and if backups are not otherwise requested.  This is the default  if
	  patch	is conforming to POSIX.

       -B pref	or  --prefix=pref
	  Prefix  pref	to  a file name	when generating	its simple backup file
	  name.	 For example, with -B /junk/ the simple	backup file  name  for
	  src/patch/util.c is /junk/src/patch/util.c.

       --binary
	  Read	and write all files in binary mode, except for standard	output
	  and /dev/tty.	 This option has no effect  on	POSIX-conforming  sys-
	  tems.	 On systems like DOS where this	option makes a difference, the
	  patch	should be generated by diff -a --binary.

       -c  or  --context
	  Interpret the	patch file as a	ordinary context diff.

       -d dir  or  --directory=dir
	  Change to the	directory dir immediately, before doing	anything else.

       -D define  or  --ifdef=define
	  Use  the #ifdef ... #endif construct to mark changes,	with define as
	  the differentiating symbol.

       --dry-run
	  Print	the results of applying	the patches without actually  changing
	  any files.

       -e  or  --ed
	  Interpret the	patch file as an ed script.

       -E  or  --remove-empty-files
	  Remove  output  files	 that  are  empty  after the patches have been
	  applied.  Normally this option is unnecessary, since patch can exam-
	  ine the time stamps on the header to determine whether a file	should
	  exist	after patching.	 However, if the input is not a	 context  diff
	  or  if  patch	 is  conforming	 to POSIX, patch does not remove empty
	  patched files	unless this option is given.   When  patch  removes  a
	  file,	it also	attempts to remove any empty ancestor directories.

       -f  or  --force
	  Assume  that	the user knows exactly what he or she is doing,	and do
	  not ask any questions.  Skip patches whose headers do	not say	 which
	  file	is  to be patched; patch files even though they	have the wrong
	  version for the Prereq: line in the patch; and assume	 that  patches
	  are  not reversed even if they look like they	are.  This option does
	  not suppress commentary; use -s for that.

       -F num  or  --fuzz=num
	  Set the maximum fuzz factor.	This option only applies to diffs that
	  have	context,  and  causes patch to ignore up to that many lines in
	  looking for places to	install	a hunk.	 Note that a larger fuzz  fac-
	  tor  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 con-
	  text in the context diff, ordinarily 3.

       -g num  or  --get=num
	  This	option	controls  patch's  actions when	a file is under	RCS or
	  SCCS control,	and does not exist or is  read-only  and  matches  the
	  default  version, or when a file is under ClearCase control and does
	  not exist.  If num is	positive, patch	gets (or checks	out) the  file
	  from	the  revision  control	system;	 if  zero,  patch ignores RCS,
	  ClearCase, and SCCS and does not get	the  file;  and	 if  negative,
	  patch	 asks  the user	whether	to get the file.  The default value of
	  this option is given by the value of the PATCH_GET environment vari-
	  able	if  it	is  set; if not, the default value is zero if patch is
	  conforming to	POSIX, negative	otherwise.

       --help
	  Print	a summary of options and exit.

       -i patchfile  or	 --input=patchfile
	  Read the patch from patchfile.  If patchfile is -, read  from	 stan-
	  dard input, the default.

       -l  or  --ignore-whitespace
	  Match	 patterns  loosely, in case tabs or spaces have	been munged in
	  your files.  Any sequence of one or more blanks in  the  patch  file
	  matches  any	sequence in the	original file, and sequences of	blanks
	  at the ends of lines are  ignored.   Normal  characters  must	 still
	  match	 exactly.  Each	line of	the context must still match a line in
	  the original file.

       -n  or  --normal
	  Interpret the	patch file as a	normal diff.

       -N  or  --forward
	  Ignore patches that seem to be reversed  or  already	applied.   See
	  also -R.

       -o outfile  or  --output=outfile
	  Send output to outfile instead of patching files in place.

       -pnum  or  --strip=num
	  Strip	 the  smallest prefix containing num leading slashes from each
	  file name found in the patch file.  A	sequence of one	or more	 adja-
	  cent	slashes	 is counted as a single	slash.	This controls how file
	  names	found in the patch file	are treated, in	 case  you  keep  your
	  files	 in  a	different  directory  than the person who sent out the
	  patch.  For example, supposing the file name in the patch file was

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

	  setting -p0 gives the	entire file name 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	option.

       --posix
	  Conform more strictly	to the POSIX standard, as follows.

	   +o Take the first existing file from the list	(old, new, index) when
	     intuiting file names from diff headers.

	   +o Do	not remove files that are empty	after patching.

	   +o Do	not ask	whether	to get files from RCS, ClearCase, or SCCS.

	   +o Require that all options precede the files	in the command line.

	   +o Do	not backup files when there is a mismatch.

       --quoting-style=word
	  Use style word to quote output names.	 The word should be one	of the
	  following:

	  literal
		 Output	names as-is.

	  shell	 Quote names for the shell if they contain  shell  metacharac-
		 ters or would cause ambiguous output.

	  shell-always
		 Quote	names  for  the	shell, even if they would normally not
		 require quoting.

	  c	 Quote names as	for a C	language string.

	  escape Quote as with c  except  omit	the  surrounding  double-quote
		 characters.

	  You can specify the default value of the --quoting-style option with
	  the environment variable QUOTING_STYLE.  If that  environment	 vari-
	  able is not set, the default value is	shell.

       -r rejectfile  or  --reject-file=rejectfile
	  Put rejects into rejectfile instead of the default .rej file.

       -R  or  --reverse
	  Assume  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.)  patch attempts to swap each hunk	around
	  before applying it.  Rejects come out	in the swapped format.	The -R
	  option  does not work	with ed	diff scripts because there is too lit-
	  tle information to reconstruct the reverse operation.

	  If the first hunk of a patch fails, patch reverses the hunk  to  see
	  if it	can be applied that way.  If it	can, you are asked if you want
	  to have the -R option	set.  If it can't, the patch continues	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  matches  anywhere.	Luckily,  most
	  patches  add	or  change  lines  rather  than	 delete	 them, so most
	  reversed normal diffs	begin with a delete, which  fails,  triggering
	  the heuristic.)

       -s  or  --silent	 or  --quiet
	  Work silently, unless	an error occurs.

       -t  or  --batch
	  Suppress  questions  like  -f,  but make some	different assumptions:
	  skip patches whose headers do	not contain file names	(the  same  as
	  -f);	skip  patches for which	the file has the wrong version for the
	  Prereq: line in the patch; and assume	that patches are  reversed  if
	  they look like they are.

       -T  or  --set-time
	  Set  the  modification  and  access times of patched files from time
	  stamps given in context diff headers,	assuming that the context diff
	  headers  use	local  time.   This option is not recommended, because
	  patches using	local time cannot easily be used by  people  in	 other
	  time	zones,	and because local time stamps are ambiguous when local
	  clocks  move	backwards  during  daylight-saving  time  adjustments.
	  Instead  of using this option, generate patches with UTC and use the
	  -Z or	--set-utc option instead.

       -u  or  --unified
	  Interpret the	patch file as a	unified	context	diff.

       -v  or  --version
	  Print	out patch's revision header and	patch level, and exit.

       -V method  or  --version-control=method
	  Use method to	determine backup file names.  The method can  also  be
	  given	 by the	PATCH_VERSION_CONTROL (or, if that's not set, the VER-
	  SION_CONTROL)	environment variable,  which  is  overridden  by  this
	  option.   The	 method	does not affect	whether	backup files are made;
	  it affects only the names of any backup files	that are made.

	  The value of method is like the GNU  Emacs  `version-control'	 vari-
	  able;	patch also recognizes synonyms that are	more descriptive.  The
	  valid	values for method are (unique abbreviations are	accepted):

	  existing  or	nil
	     Make numbered backups of files that already have them,  otherwise
	     simple backups.  This is the default.

	  numbered  or	t
	     Make  numbered  backups.	The numbered backup file name for F is
	     F.~N~ where N is the version number.

	  simple  or  never
	     Make simple backups.  The -B or --prefix, -Y  or  --basename-pre-
	     fix,  and	-z  or --suffix	options	specify	the simple backup file
	     name.  If none of these options are given,	then a	simple	backup
	     suffix is used; it	is the value of	the SIMPLE_BACKUP_SUFFIX envi-
	     ronment variable if set, and is .orig otherwise.

	  With numbered	or simple backups, if the  backup  file	 name  is  too
	  long,	the backup suffix ~ is used instead; if	even appending ~ would
	  make the name	too long, then ~ replaces the last  character  of  the
	  file name.

       --verbose
	  Output extra information about the work being	done.

       -x num  or  --debug=num
	  Set internal debugging flags of interest only	to patch patchers.

       -Y pref	or  --basename-prefix=pref
	  Prefix  pref to the basename of a file name when generating its sim-
	  ple backup file name.	 For example, with -Y .del/ the	simple	backup
	  file name for	src/patch/util.c is src/patch/.del/util.c.

       -z suffix  or  --suffix=suffix
	  Use  suffix as the simple backup suffix.  For	example, with -z - the
	  simple backup	file name for src/patch/util.c	is  src/patch/util.c-.
	  The  backup suffix may also be specified by the SIMPLE_BACKUP_SUFFIX
	  environment variable,	which is overridden by this option.

       -Z  or  --set-utc
	  Set the modification and access times	of  patched  files  from  time
	  stamps given in context diff headers,	assuming that the context diff
	  headers use Coordinated Universal Time (UTC, often  known  as	 GMT).
	  Also see the -T or --set-time	option.

	  The  -Z  or  --set-utc and -T	or --set-time options normally refrain
	  from setting a file's	time if	the  file's  original  time  does  not
	  match	 the time given	in the patch header, or	if its contents	do not
	  match	the patch exactly.  However, if	the -f or  --force  option  is
	  given, the file time is set regardless.

	  Due  to  the limitations of diff output format, these	options	cannot
	  update the times of files whose contents have	not changed.  Also, if
	  you  use these options, you should remove (e.g. with make clean) all
	  files	that depend on the patched files, so that later	invocations of
	  make do not get confused by the patched files' times.

ENVIRONMENT
       PATCH_GET
	  This	specifies  whether  patch gets missing or read-only files from
	  RCS, ClearCase, or SCCS by default; see the -g or --get option.

       POSIXLY_CORRECT
	  If set, patch	conforms  more	strictly  to  the  POSIX  standard  by
	  default: see the --posix option.

       QUOTING_STYLE
	  Default value	of the --quoting-style option.

       SIMPLE_BACKUP_SUFFIX
	  Extension to use for simple backup file names	instead	of .orig.

       TMPDIR, TMP, TEMP
	  Directory  to	 put temporary files in; patch uses the	first environ-
	  ment variable	in this	list that  is  set.   If  none	are  set,  the
	  default is system-dependent; it is normally /tmp on Unix hosts.

       VERSION_CONTROL or PATCH_VERSION_CONTROL
	  Selects  version  control  style;  see  the  -v or --version-control
	  option.

FILES
       $TMPDIR/p*
	  temporary files

       /dev/tty
	  controlling terminal;	used to	get answers to questions asked of  the
	  user

SEE ALSO
       diff(1),	ed(1)

       Marshall	 T. Rose and Einar A. Stefferud, Proposed Standard for Message
       Encapsulation,	 Internet    RFC    934	    <URL:ftp://ftp.isi.edu/in-
       notes/rfc934.txt> (1985-01).

NOTES FOR PATCH	SENDERS
       There are several things	you should bear	in mind	if you are going to be
       sending out patches.

       Create your  patch  systematically.   A	good  method  is  the  command
       diff -Naur old new  where old and new identify the old and new directo-
       ries.  The names	old and	new should not contain any slashes.  The  diff
       command's  headers  should have dates and times in Universal Time using
       traditional Unix	format,	so that	patch recipients can  use  the	-Z  or
       --set-utc  option.  Here	is an example command, using Bourne shell syn-
       tax:

	  LC_ALL=C TZ=UTC0 diff	-Naur gcc-2.7 gcc-2.8

       Tell your recipients how	to apply  the  patch  by  telling  them	 which
       directory  to cd	to, and	which patch options to use.  The option	string
       -Np1 is recommended.  Test your procedure by pretending to be a recipi-
       ent and applying	your patch to a	copy of	the original files.

       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.

       You can create a	file by	sending	out a diff that	compares /dev/null  or
       an empty	file dated the Epoch (1970-01-01 00:00:00 UTC) to the file you
       want to create.	This only works	if the file you	want to	create doesn't
       exist  already  in  the target directory.  Conversely, you can remove a
       file by sending out a context diff that compares	the file to be deleted
       with  an	 empty	file dated the Epoch.  The file	will be	removed	unless
       patch is	conforming to POSIX and	the -E or --remove-empty-files	option
       is  not	given.	An easy	way to generate	patches	that create and	remove
       files is	to use GNU diff's -N or	--new-file option.

       If the recipient	is supposed to use the -pN option, do not send	output
       that looks like this:

	  diff -Naur v2.0.29/prog/README prog/README
	  --- v2.0.29/prog/README   Mon	Mar 10 15:13:12	1997
	  +++ prog/README   Mon	Mar 17 14:58:22	1997

       because	the two	file names have	different numbers of slashes, and dif-
       ferent versions of patch	interpret  the	file  names  differently.   To
       avoid confusion,	send output that looks like this instead:

	  diff -Naur v2.0.29/prog/README v2.0.30/prog/README
	  --- v2.0.29/prog/README   Mon	Mar 10 15:13:12	1997
	  +++ v2.0.30/prog/README   Mon	Mar 17 14:58:22	1997

       Avoid  sending patches that compare backup file names like README.orig,
       since this might	confuse	patch into patching a backup file  instead  of
       the  real  file.	 Instead, send patches that compare the	same base file
       names in	different directories, e.g. old/README and new/README.

       Take care not to	send out reversed patches, since it makes people  won-
       der whether they	already	applied	the patch.

       Try  not	to have	your patch modify derived files	(e.g. the file config-
       ure where there is a line configure: configure.in  in  your  makefile),
       since the recipient should be able to regenerate	the derived files any-
       way.  If	you must send diffs of derived files, generate the diffs using
       UTC,  have  the	recipients  apply  the	patch with the -Z or --set-utc
       option, and have	them remove any	unpatched files	that depend on patched
       files (e.g. with	make clean).

       While  you  may be able to get away with	putting	582 diff listings into
       one file, it may	be wiser to group related patches into separate	 files
       in case something goes haywire.

DIAGNOSTICS
       Diagnostics  generally  indicate	 that  patch couldn't parse your patch
       file.

       If the --verbose	option is given, the  message  Hmm...  indicates  that
       there  is unprocessed text in the patch file and	that patch is attempt-
       ing to intuit whether there is a	patch in that text and,	 if  so,  what
       kind of patch it	is.

       patch's	exit  status  is 0 if all hunks	are applied successfully, 1 if
       some hunks cannot be applied, and 2 if there is more  serious  trouble.
       When  applying a	set of patches in a loop it behooves you to check this
       exit status so you don't	apply a	later patch  to	 a  partially  patched
       file.

CAVEATS
       Context	diffs  cannot  reliably	 represent the creation	or deletion of
       empty files, empty directories,	or  special  files  such  as  symbolic
       links.  Nor can they represent changes to file metadata like ownership,
       permissions, or whether one file	is a hard link to another.  If changes
       like  these  are	 also  required,  separate  instructions (e.g. a shell
       script) to accomplish them should accompany the patch.

       patch cannot tell if the	line numbers are off in	an ed script, and  can
       detect bad line numbers in a normal diff	only when it finds a change or
       deletion.  A context diff using fuzz factor 3 may have the  same	 prob-
       lem.  Until a suitable interactive interface is added, you should prob-
       ably 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.

       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.

COMPATIBILITY ISSUES
       The  POSIX standard specifies behavior that differs from	patch's	tradi-
       tional behavior.	 You should be aware of	these differences if you  must
       interoperate  with patch	versions 2.1 and earlier, which	do not conform
       to POSIX.

	+o In traditional patch,	the -p option's	operand	was  optional,	and  a
	  bare	-p was equivalent to -p0.  The -p option now requires an oper-
	  and, and -p 0	is now equivalent to -p0.  For maximum	compatibility,
	  use options like -p0 and -p1.

	  Also,	 traditional  patch simply counted slashes when	stripping path
	  prefixes; patch now counts pathname components.  That	is, a sequence
	  of  one  or more adjacent slashes now	counts as a single slash.  For
	  maximum portability, avoid sending patches  containing  //  in  file
	  names.

	+o In  traditional patch, backups were enabled by default.  This	behav-
	  ior is now enabled with the -b or --backup option.

	  Conversely, in POSIX patch, backups are never	made, even when	 there
	  is  a	 mismatch.   In	 GNU  patch, this behavior is enabled with the
	  --no-backup-if-mismatch option, or by	conforming to POSIX  with  the
	  --posix  option  or by setting the POSIXLY_CORRECT environment vari-
	  able.

	  The -b suffix	option of  traditional	patch  is  equivalent  to  the
	  -b -z	suffix options of GNU patch.

	+o Traditional  patch  used a complicated (and incompletely documented)
	  method to intuit the name of the file	to be patched from  the	 patch
	  header.   This  method  did  not  conform  to	 POSIX,	 and had a few
	  gotchas.  Now	patch uses a different,	equally	complicated (but  bet-
	  ter  documented) method that is optionally POSIX-conforming; we hope
	  it has fewer gotchas.	 The two methods are compatible	 if  the  file
	  names	in the context diff header and the Index: line are all identi-
	  cal after prefix-stripping.  Your patch is  normally	compatible  if
	  each header's	file names all contain the same	number of slashes.

	+o When	traditional patch asked	the user a question, it	sent the ques-
	  tion to standard error and looked for	an answer from the first  file
	  in  the following list that was a terminal: standard error, standard
	  output, /dev/tty, and	standard input.	 Now patch sends questions  to
	  standard  output  and	gets answers from /dev/tty.  Defaults for some
	  answers have been changed so that patch never	goes into an  infinite
	  loop when using default answers.

	+o Traditional patch exited with	a status value that counted the	number
	  of bad hunks,	or with	status 1 if there was real trouble.  Now patch
	  exits	 with  status  1  if some hunks	failed,	or with	2 if there was
	  real trouble.

	+o Limit	yourself to the	following options  when	 sending  instructions
	  meant	to be executed by anyone running GNU patch, traditional	patch,
	  or a patch that conforms to POSIX.  Spaces are  significant  in  the
	  following list, and operands are required.

	     -c
	     -d	dir
	     -D	define
	     -e
	     -l
	     -n
	     -N
	     -o	outfile
	     -pnum
	     -R
	     -r	rejectfile

BUGS
       Please report bugs via email to <bug-gnu-utils@gnu.org>.

       patch  could be smarter about partial matches, excessively deviant off-
       sets and	swapped	code, but that would take an extra pass.

       If code has been	duplicated (for	instance with #ifdef OLDCODE ... #else
       ...  #endif),  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.

       If  you	apply  a  patch	 you've	 already applied, patch	thinks it is a
       reversed	patch, and offers to un-apply the patch.  This could  be  con-
       strued as a feature.

COPYING
       Copyright 1984, 1985, 1986, 1988	Larry Wall.
       Copyright  1989,	 1990,	1991, 1992, 1993, 1994,	1995, 1996, 1997, 1998
       Free Software Foundation, Inc.

       Permission is granted to	make and distribute verbatim  copies  of  this
       manual  provided	 the  copyright	 notice	and this permission notice are
       preserved on all	copies.

       Permission is granted to	copy and distribute modified versions of  this
       manual  under  the  conditions  for verbatim copying, provided that the
       entire resulting	derived	work is	distributed under the terms of a  per-
       mission notice identical	to this	one.

       Permission  is granted to copy and distribute translations of this man-
       ual into	another	language, under	the above conditions for modified ver-
       sions,  except  that this permission notice may be included in transla-
       tions approved by the copyright holders	instead	 of  in	 the  original
       English.

AUTHORS
       Larry  Wall  wrote  the original	version	of patch.  Paul	Eggert removed
       patch's arbitrary limits; added support for binary files, setting  file
       times,  and deleting files; and made it conform better to POSIX.	 Other
       contributors include Wayne Davison,  who	 added	unidiff	 support,  and
       David MacKenzie,	who added configuration	and backup support.

GNU				  1998/03/21			      PATCH(1)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | ENVIRONMENT | FILES | SEE ALSO | NOTES FOR PATCH SENDERS | DIAGNOSTICS | CAVEATS | COMPATIBILITY ISSUES | BUGS | COPYING | AUTHORS

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