1PATCH(1) General Commands Manual PATCH(1)
2
6 patch - apply a diff file to an original
7
9 patch [options] [originalfile [patchfile]]
10 but usually just
12 patch -pnum <patchfile
14
16 patch takes a patch file patchfile containing a difference listing pro‐
17 duced by the diff program and applies those differences to one or more
18 original files, producing patched versions. Normally the patched ver‐
19 sions are put in place of the originals. Backups can be made; see the
20 -b or --backup option. The names of the files to be patched are usu‐
21 ally taken from the patch file, but if there's just one file to be
22 patched it can be specified on the command line as originalfile.
23 Upon startup, patch attempts to determine the type of the diff listing,
25 unless overruled by a -c (--context), -e (--ed), -n (--normal), or -u
26 (--unified) option. Context diffs (old-style, new-style, and unified)
27 and normal diffs are applied by the patch program itself, while ed
28 diffs are simply fed to the ed(1) editor via a pipe.
29 patch tries to skip any leading garbage, apply the diff, and then skip
31 any trailing garbage. Thus you could feed an article or message con‐
32 taining a diff listing to patch, and it should work. If the entire
33 diff is indented by a consistent amount, if lines end in CRLF, or if a
34 diff is encapsulated one or more times by prepending "- " to lines
35 starting with "-" as specified by Internet RFC 934, this is taken into
36 account. After removing indenting or encapsulation, lines beginning
37 with # are ignored, as they are considered to be comments.
38 With context diffs, and to a lesser extent with normal diffs, patch can
40 detect when the line numbers mentioned in the patch are incorrect, and
41 attempts to find the correct place to apply each hunk of the patch. As
42 a first guess, it takes the line number mentioned for the hunk, plus or
43 minus any offset used in applying the previous hunk. If that is not
44 the correct place, patch scans both forwards and backwards for a set of
45 lines matching the context given in the hunk. First patch looks for a
46 place where all lines of the context match. If no such place is found,
47 and it's a context diff, and the maximum fuzz factor is set to 1 or
48 more, then another scan takes place ignoring the first and last line of
49 context. If that fails, and the maximum fuzz factor is set to 2 or
50 more, the first two and last two lines of context are ignored, and
51 another scan is made. (The default maximum fuzz factor is 2.)
52 Hunks with less prefix context than suffix context (after applying
54 fuzz) must apply at the start of the file if their first line number
55 is 1. Hunks with more prefix context than suffix context (after apply‐
56 ing fuzz) must apply at the end of the file.
57 If patch cannot find a place to install that hunk of the patch, it puts
59 the hunk out to a reject file, which normally is the name of the output
60 file plus a .rej suffix, or # if .rej would generate a file name that
61 is too long (if even appending the single character # makes the file
62 name too long, then # replaces the file name's last character).
63 The rejected hunk comes out in unified or context diff format. If the
65 input was a normal diff, many of the contexts are simply null. The
66 line numbers on the hunks in the reject file may be different than in
67 the patch file: they reflect the approximate location patch thinks the
68 failed hunks belong in the new file rather than the old one.
69 As each hunk is completed, you are told if the hunk failed, and if so
71 which line (in the new file) patch thought the hunk should go on. If
72 the hunk is installed at a different line from the line number speci‐
73 fied in the diff, you are told the offset. A single large offset may
74 indicate that a hunk was installed in the wrong place. You are also
75 told if a fuzz factor was used to make the match, in which case you
76 should also be slightly suspicious. If the --verbose option is given,
77 you are also told about hunks that match exactly.
78 If no original file origfile is specified on the command line, patch
80 tries to figure out from the leading garbage what the name of the file
81 to edit is, using the following rules.
82 First, patch takes an ordered list of candidate file names as follows:
84 · If the header is that of a context diff, patch takes the old and new
86 file names in the header. A name is ignored if it does not have
87 enough slashes to satisfy the -pnum or --strip=num option. The name
88 /dev/null is also ignored.
89 · If there is an Index: line in the leading garbage and if either the
91 old and new names are both absent or if patch is conforming to
92 POSIX, patch takes the name in the Index: line.
93 · For the purpose of the following rules, the candidate file names are
95 considered to be in the order (old, new, index), regardless of the
96 order that they appear in the header.
97 Then patch selects a file name from the candidate list as follows:
99 · If some of the named files exist, patch selects the first name if
101 conforming to POSIX, and the best name otherwise.
102 · If patch is not ignoring RCS, ClearCase, Perforce, and SCCS (see the
104 -g num or --get=num option), and no named files exist but an RCS,
105 ClearCase, Perforce, or SCCS master is found, patch selects the
106 first named file with an RCS, ClearCase, Perforce, or SCCS master.
107 · If no named files exist, no RCS, ClearCase, Perforce, or SCCS master
109 was found, some names are given, patch is not conforming to POSIX,
110 and the patch appears to create a file, patch selects the best name
111 requiring the creation of the fewest directories.
112 · If no file name results from the above heuristics, you are asked for
114 the name of the file to patch, and patch selects that name.
115 To determine the best of a nonempty list of file names, patch first
117 takes all the names with the fewest path name components; of those, it
118 then takes all the names with the shortest basename; of those, it then
119 takes all the shortest names; finally, it takes the first remaining
120 name.
121 Additionally, if the leading garbage contains a Prereq: line, patch
123 takes the first word from the prerequisites line (normally a version
124 number) and checks the original file to see if that word can be found.
125 If not, patch asks for confirmation before proceeding.
126 The upshot of all this is that you should be able to say, while in a
128 news interface, something like the following:
129 | patch -d /usr/src/local/blurfl
131 and patch a file in the blurfl directory directly from the article con‐
133 taining the patch.
134 If the patch file contains more than one patch, patch tries to apply
136 each of them as if they came from separate patch files. This means,
137 among other things, that it is assumed that the name of the file to
138 patch must be determined for each diff listing, and that the garbage
139 before each diff listing contains interesting things such as file names
140 and revision level, as mentioned previously.
141
143 -b or --backup
144 Make backup files. That is, when patching a file, rename or copy
145 the original instead of removing it. When backing up a file that
146 does not exist, an empty, unreadable backup file is created as a
147 placeholder to represent the nonexistent file. See the -V or --ver‐
148 sion-control option for details about how backup file names are
149 determined.
150 --backup-if-mismatch
152 Back up a file if the patch does not match the file exactly and if
153 backups are not otherwise requested. This is the default unless
154 patch is conforming to POSIX.
155 --no-backup-if-mismatch
157 Do not back up a file if the patch does not match the file exactly
158 and if backups are not otherwise requested. This is the default if
159 patch is conforming to POSIX.
160 -B pref or --prefix=pref
162 Use the simple method to determine backup file names (see the -V
163 method or --version-control method option), and append pref to a
164 file name when generating its backup file name. For example, with
165 -B /junk/ the simple backup file name for src/patch/util.c is
166 /junk/src/patch/util.c.
167 --binary
169 Write all files in binary mode, except for standard output and
170 /dev/tty. When reading, disable the heuristic for transforming CRLF
171 line endings into LF line endings. This option is needed on POSIX
172 systems when applying patches generated on non-POSIX systems to non-
173 POSIX files. (On POSIX systems, file reads and writes never trans‐
174 form line endings. On Windows, reads and writes do transform line
175 endings by default, and patches should be generated by diff --binary
176 when line endings are significant.)
177 -c or --context
179 Interpret the patch file as a ordinary context diff.
180 -d dir or --directory=dir
182 Change to the directory dir immediately, before doing anything else.
183 -D define or --ifdef=define
185 Use the #ifdef ... #endif construct to mark changes, with define as
186 the differentiating symbol.
187 --dry-run
189 Print the results of applying the patches without actually changing
190 any files.
191 -e or --ed
193 Interpret the patch file as an ed script.
194 -E or --remove-empty-files
196 Remove output files that are empty after the patches have been
197 applied. Normally this option is unnecessary, since patch can exam‐
198 ine the time stamps on the header to determine whether a file should
199 exist after patching. However, if the input is not a context diff
200 or if patch is conforming to POSIX, patch does not remove empty
201 patched files unless this option is given. When patch removes a
202 file, it also attempts to remove any empty ancestor directories.
203 -f or --force
205 Assume that the user knows exactly what he or she is doing, and do
206 not ask any questions. Skip patches whose headers do not say which
207 file is to be patched; patch files even though they have the wrong
208 version for the Prereq: line in the patch; and assume that patches
209 are not reversed even if they look like they are. This option does
210 not suppress commentary; use -s for that.
211 -F num or --fuzz=num
213 Set the maximum fuzz factor. This option only applies to diffs that
214 have context, and causes patch to ignore up to that many lines of
215 context in looking for places to install a hunk. Note that a larger
216 fuzz factor increases the odds of a faulty patch. The default fuzz
217 factor is 2. A fuzz factor greater than or equal to the number of
218 lines of context in the context diff, ordinarily 3, ignores all con‐
219 text.
220 -g num or --get=num
222 This option controls patch's actions when a file is under RCS or
223 SCCS control, and does not exist or is read-only and matches the
224 default version, or when a file is under ClearCase or Perforce con‐
225 trol and does not exist. If num is positive, patch gets (or checks
226 out) the file from the revision control system; if zero, patch
227 ignores RCS, ClearCase, Perforce, and SCCS and does not get the
228 file; and if negative, patch asks the user whether to get the file.
229 The default value of this option is given by the value of the
230 PATCH_GET environment variable if it is set; if not, the default
231 value is zero.
232 --help
234 Print a summary of options and exit.
235 -i patchfile or --input=patchfile
237 Read the patch from patchfile. If patchfile is -, read from stan‐
238 dard input, the default.
239 -l or --ignore-whitespace
241 Match patterns loosely, in case tabs or spaces have been munged in
242 your files. Any sequence of one or more blanks in the patch file
243 matches any sequence in the original file, and sequences of blanks
244 at the ends of lines are ignored. Normal characters must still
245 match exactly. Each line of the context must still match a line in
246 the original file.
247 --merge or --merge=merge or --merge=diff3
249 Merge a patch file into the original files similar to diff3(1) or
250 merge(1). If a conflict is found, patch outputs a warning and
251 brackets the conflict with <<<<<<< and >>>>>>> lines. A typical
252 conflict will look like this:
253 <<<<<<<
255 lines from the original file
256 |||||||
257 original lines from the patch
258 =======
259 new lines from the patch
260 >>>>>>>
261 The optional argument of --merge determines the output format for
263 conflicts: the diff3 format shows the ||||||| section with the orig‐
264 inal lines from the patch; in the merge format, this section is
265 missing. The merge format is the default.
266 This option implies --forward and does not take the --fuzz=num
268 option into account.
269 -n or --normal
271 Interpret the patch file as a normal diff.
272 -N or --forward
274 Ignore patches that seem to be reversed or already applied. It is
275 only checked if the first hunk of a patch can be reversed. See also
276 -R.
277 -o outfile or --output=outfile
279 Send output to outfile instead of patching files in place. Do not
280 use this option if outfile is one of the files to be patched. When
281 outfile is -, send output to standard output, and send any messages
282 that would usually go to standard output to standard error.
283 -pnum or --strip=num
285 Strip the smallest prefix containing num leading slashes from each
286 file name found in the patch file. A sequence of one or more adja‐
287 cent slashes is counted as a single slash. This controls how file
288 names found in the patch file are treated, in case you keep your
289 files in a different directory than the person who sent out the
290 patch. For example, supposing the file name in the patch file was
291 /u/howard/src/blurfl/blurfl.c
293 setting -p0 gives the entire file name unmodified, -p1 gives
295 u/howard/src/blurfl/blurfl.c
297 without the leading slash, -p4 gives
299 blurfl/blurfl.c
301 and not specifying -p at all just gives you blurfl.c. Whatever you
303 end up with is looked for either in the current directory, or the
304 directory specified by the -d option.
305 --posix
307 Conform more strictly to the POSIX standard, as follows.
308 · Take the first existing file from the list (old, new, index) when
310 intuiting file names from diff headers.
311 · Do not remove files that are empty after patching.
313 · Do not ask whether to get files from RCS, ClearCase, Perforce, or
315 SCCS.
316 · Require that all options precede the files in the command line.
318 · Do not backup files when there is a mismatch.
320 --quoting-style=word
322 Use style word to quote output names. The word should be one of the
323 following:
324 literal
326 Output names as-is.
327 shell Quote names for the shell if they contain shell metacharac‐
329 ters or would cause ambiguous output.
330 shell-always
332 Quote names for the shell, even if they would normally not
333 require quoting.
334 c Quote names as for a C language string.
336 escape Quote as with c except omit the surrounding double-quote
338 characters.
339 You can specify the default value of the --quoting-style option with
341 the environment variable QUOTING_STYLE. If that environment vari‐
342 able is not set, the default value is shell.
343 -r rejectfile or --reject-file=rejectfile
345 Put rejects into rejectfile instead of the default .rej file. When
346 rejectfile is -, discard rejects.
347 -R or --reverse
349 Assume that this patch was created with the old and new files
350 swapped. (Yes, I'm afraid that does happen occasionally, human
351 nature being what it is.) patch attempts to swap each hunk around
352 before applying it. Rejects come out in the swapped format. The -R
353 option does not work with ed diff scripts because there is too lit‐
354 tle information to reconstruct the reverse operation.
355 If the first hunk of a patch fails, patch reverses the hunk to see
357 if it can be applied that way. If it can, you are asked if you want
358 to have the -R option set. If it can't, the patch continues to be
359 applied normally. (Note: this method cannot detect a reversed patch
360 if it is a normal diff and if the first command is an append (i.e.
361 it should have been a delete) since appends always succeed, due to
362 the fact that a null context matches anywhere. Luckily, most
363 patches add or change lines rather than delete them, so most
364 reversed normal diffs begin with a delete, which fails, triggering
365 the heuristic.)
366 --read-only=behavior
368 Behave as requested when trying to modify a read-only file: ignore
369 the potential problem, warn about it (the default), or fail.
370 --reject-format=format
372 Produce reject files in the specified format (either context or uni‐
373 fied). Without this option, rejected hunks come out in unified diff
374 format if the input patch was of that format, otherwise in ordinary
375 context diff form.
376 -s or --silent or --quiet
378 Work silently, unless an error occurs.
379 --follow-symlinks
381 When looking for input files, follow symbolic links. Replaces the
382 symbolic links, instead of modifying the files the symbolic links
383 point to. Git-style patches to symbolic links will no longer apply.
384 This option exists for backwards compatibility with previous ver‐
385 sions of patch; its use is discouraged.
386 -t or --batch
388 Suppress questions like -f, but make some different assumptions:
389 skip patches whose headers do not contain file names (the same as
390 -f); skip patches for which the file has the wrong version for the
391 Prereq: line in the patch; and assume that patches are reversed if
392 they look like they are.
393 -T or --set-time
395 Set the modification and access times of patched files from time
396 stamps given in context diff headers. Unless specified in the time
397 stamps, assume that the context diff headers use local time.
398 Use of this option with time stamps that do not include time zones
400 is not recommended, because patches using local time cannot easily
401 be used by people in other time zones, and because local time stamps
402 are ambiguous when local clocks move backwards during daylight-sav‐
403 ing time adjustments. Make sure that time stamps include time
404 zones, or generate patches with UTC and use the -Z or --set-utc
405 option instead.
406 -u or --unified
408 Interpret the patch file as a unified context diff.
409 -v or --version
411 Print out patch's revision header and patch level, and exit.
412 -V method or --version-control=method
414 Use method to determine backup file names. The method can also be
415 given by the PATCH_VERSION_CONTROL (or, if that's not set, the VER‐
416 SION_CONTROL) environment variable, which is overridden by this
417 option. The method does not affect whether backup files are made;
418 it affects only the names of any backup files that are made.
419 The value of method is like the GNU Emacs `version-control' vari‐
421 able; patch also recognizes synonyms that are more descriptive. The
422 valid values for method are (unique abbreviations are accepted):
423 existing or nil
425 Make numbered backups of files that already have them, otherwise
426 simple backups. This is the default.
427 numbered or t
429 Make numbered backups. The numbered backup file name for F is
430 F.~N~ where N is the version number.
431 simple or never
433 Make simple backups. The -B or --prefix, -Y or --basename-pre‐
434 fix, and -z or --suffix options specify the simple backup file
435 name. If none of these options are given, then a simple backup
436 suffix is used; it is the value of the SIMPLE_BACKUP_SUFFIX envi‐
437 ronment variable if set, and is .orig otherwise.
438 With numbered or simple backups, if the backup file name is too
440 long, the backup suffix ~ is used instead; if even appending ~ would
441 make the name too long, then ~ replaces the last character of the
442 file name.
443 --verbose
445 Output extra information about the work being done.
446 -x num or --debug=num
448 Set internal debugging flags of interest only to patch patchers.
449 -Y pref or --basename-prefix=pref
451 Use the simple method to determine backup file names (see the -V
452 method or --version-control method option), and prefix pref to the
453 basename of a file name when generating its backup file name. For
454 example, with -Y .del/ the simple backup file name for
455 src/patch/util.c is src/patch/.del/util.c.
456 -z suffix or --suffix=suffix
458 Use the simple method to determine backup file names (see the -V
459 method or --version-control method option), and use suffix as the
460 suffix. For example, with -z - the backup file name for
461 src/patch/util.c is src/patch/util.c-.
462 -Z or --set-utc
464 Set the modification and access times of patched files from time
465 stamps given in context diff headers. Unless specified in the time
466 stamps, assume that the context diff headers use Coordinated Univer‐
467 sal Time (UTC, often known as GMT). Also see the -T or --set-time
468 option.
469 The -Z or --set-utc and -T or --set-time options normally refrain
471 from setting a file's time if the file's original time does not
472 match the time given in the patch header, or if its contents do not
473 match the patch exactly. However, if the -f or --force option is
474 given, the file time is set regardless.
475 Due to the limitations of diff output format, these options cannot
477 update the times of files whose contents have not changed. Also, if
478 you use these options, you should remove (e.g. with make clean) all
479 files that depend on the patched files, so that later invocations of
480 make do not get confused by the patched files' times.
481
483 PATCH_GET
484 This specifies whether patch gets missing or read-only files from
485 RCS, ClearCase, Perforce, or SCCS by default; see the -g or --get
486 option.
487 POSIXLY_CORRECT
489 If set, patch conforms more strictly to the POSIX standard by
490 default: see the --posix option.
491 QUOTING_STYLE
493 Default value of the --quoting-style option.
494 SIMPLE_BACKUP_SUFFIX
496 Extension to use for simple backup file names instead of .orig.
497 TMPDIR, TMP, TEMP
499 Directory to put temporary files in; patch uses the first environ‐
500 ment variable in this list that is set. If none are set, the
501 default is system-dependent; it is normally /tmp on Unix hosts.
502 VERSION_CONTROL or PATCH_VERSION_CONTROL
504 Selects version control style; see the -v or --version-control
505 option.
506
508 $TMPDIR/p*
509 temporary files
510 /dev/tty
512 controlling terminal; used to get answers to questions asked of the
513 user
514
516 diff(1), ed(1), merge(1).
517 Marshall T. Rose and Einar A. Stefferud, Proposed Standard for Message
519 Encapsulation, Internet RFC 934 <URL:ftp://ftp.isi.edu/in-
520 notes/rfc934.txt> (1985-01).
521
523 There are several things you should bear in mind if you are going to be
524 sending out patches.
525 Create your patch systematically. A good method is the command
527 diff -Naur old new where old and new identify the old and new directo‐
528 ries. The names old and new should not contain any slashes. The diff
529 command's headers should have dates and times in Universal Time using
530 traditional Unix format, so that patch recipients can use the -Z or
531 --set-utc option. Here is an example command, using Bourne shell syn‐
532 tax:
533 LC_ALL=C TZ=UTC0 diff -Naur gcc-2.7 gcc-2.8
535 Tell your recipients how to apply the patch by telling them which
537 directory to cd to, and which patch options to use. The option string
538 -Np1 is recommended. Test your procedure by pretending to be a recipi‐
539 ent and applying your patch to a copy of the original files.
540 You can save people a lot of grief by keeping a patchlevel.h file which
542 is patched to increment the patch level as the first diff in the patch
543 file you send out. If you put a Prereq: line in with the patch, it
544 won't let them apply patches out of order without some warning.
545 You can create a file by sending out a diff that compares /dev/null or
547 an empty file dated the Epoch (1970-01-01 00:00:00 UTC) to the file you
548 want to create. This only works if the file you want to create doesn't
549 exist already in the target directory. Conversely, you can remove a
550 file by sending out a context diff that compares the file to be deleted
551 with an empty file dated the Epoch. The file will be removed unless
552 patch is conforming to POSIX and the -E or --remove-empty-files option
553 is not given. An easy way to generate patches that create and remove
554 files is to use GNU diff's -N or --new-file option.
555 If the recipient is supposed to use the -pN option, do not send output
557 that looks like this:
558 diff -Naur v2.0.29/prog/README prog/README
560 --- v2.0.29/prog/README Mon Mar 10 15:13:12 1997
561 +++ prog/README Mon Mar 17 14:58:22 1997
562 because the two file names have different numbers of slashes, and dif‐
564 ferent versions of patch interpret the file names differently. To
565 avoid confusion, send output that looks like this instead:
566 diff -Naur v2.0.29/prog/README v2.0.30/prog/README
568 --- v2.0.29/prog/README Mon Mar 10 15:13:12 1997
569 +++ v2.0.30/prog/README Mon Mar 17 14:58:22 1997
570 Avoid sending patches that compare backup file names like README.orig,
573 since this might confuse patch into patching a backup file instead of
574 the real file. Instead, send patches that compare the same base file
575 names in different directories, e.g. old/README and new/README.
576 Take care not to send out reversed patches, since it makes people won‐
578 der whether they already applied the patch.
579 Try not to have your patch modify derived files (e.g. the file config‐
581 ure where there is a line configure: configure.in in your makefile),
582 since the recipient should be able to regenerate the derived files any‐
583 way. If you must send diffs of derived files, generate the diffs using
584 UTC, have the recipients apply the patch with the -Z or --set-utc
585 option, and have them remove any unpatched files that depend on patched
586 files (e.g. with make clean).
587 While you may be able to get away with putting 582 diff listings into
589 one file, it may be wiser to group related patches into separate files
590 in case something goes haywire.
591
593 Diagnostics generally indicate that patch couldn't parse your patch
594 file.
595 If the --verbose option is given, the message Hmm... indicates that
597 there is unprocessed text in the patch file and that patch is attempt‐
598 ing to intuit whether there is a patch in that text and, if so, what
599 kind of patch it is.
600 patch's exit status is 0 if all hunks are applied successfully, 1 if
602 some hunks cannot be applied or there were merge conflicts, and 2 if
603 there is more serious trouble. When applying a set of patches in a
604 loop it behooves you to check this exit status so you don't apply a
605 later patch to a partially patched file.
606
608 Context diffs cannot reliably represent the creation or deletion of
609 empty files, empty directories, or special files such as symbolic
610 links. Nor can they represent changes to file metadata like ownership,
611 permissions, or whether one file is a hard link to another. If changes
612 like these are also required, separate instructions (e.g. a shell
613 script) to accomplish them should accompany the patch.
614 patch cannot tell if the line numbers are off in an ed script, and can
616 detect bad line numbers in a normal diff only when it finds a change or
617 deletion. A context diff using fuzz factor 3 may have the same prob‐
618 lem. You should probably do a context diff in these cases to see if
619 the changes made sense. Of course, compiling without errors is a
620 pretty good indication that the patch worked, but not always.
621 patch usually produces the correct results, even when it has to do a
623 lot of guessing. However, the results are guaranteed to be correct
624 only when the patch is applied to exactly the same version of the file
625 that the patch was generated from.
626
628 The POSIX standard specifies behavior that differs from patch's tradi‐
629 tional behavior. You should be aware of these differences if you must
630 interoperate with patch versions 2.1 and earlier, which do not conform
631 to POSIX.
632 · In traditional patch, the -p option's operand was optional, and a
634 bare -p was equivalent to -p0. The -p option now requires an oper‐
635 and, and -p 0 is now equivalent to -p0. For maximum compatibility,
636 use options like -p0 and -p1.
637 Also, traditional patch simply counted slashes when stripping path
639 prefixes; patch now counts pathname components. That is, a sequence
640 of one or more adjacent slashes now counts as a single slash. For
641 maximum portability, avoid sending patches containing // in file
642 names.
643 · In traditional patch, backups were enabled by default. This behav‐
645 ior is now enabled with the -b or --backup option.
646 Conversely, in POSIX patch, backups are never made, even when there
648 is a mismatch. In GNU patch, this behavior is enabled with the
649 --no-backup-if-mismatch option, or by conforming to POSIX with the
650 --posix option or by setting the POSIXLY_CORRECT environment vari‐
651 able.
652 The -b suffix option of traditional patch is equivalent to the
654 -b -z suffix options of GNU patch.
655 · Traditional patch used a complicated (and incompletely documented)
657 method to intuit the name of the file to be patched from the patch
658 header. This method did not conform to POSIX, and had a few
659 gotchas. Now patch uses a different, equally complicated (but bet‐
660 ter documented) method that is optionally POSIX-conforming; we hope
661 it has fewer gotchas. The two methods are compatible if the file
662 names in the context diff header and the Index: line are all identi‐
663 cal after prefix-stripping. Your patch is normally compatible if
664 each header's file names all contain the same number of slashes.
665 · When traditional patch asked the user a question, it sent the ques‐
667 tion to standard error and looked for an answer from the first file
668 in the following list that was a terminal: standard error, standard
669 output, /dev/tty, and standard input. Now patch sends questions to
670 standard output and gets answers from /dev/tty. Defaults for some
671 answers have been changed so that patch never goes into an infinite
672 loop when using default answers.
673 · Traditional patch exited with a status value that counted the number
675 of bad hunks, or with status 1 if there was real trouble. Now patch
676 exits with status 1 if some hunks failed, or with 2 if there was
677 real trouble.
678 · Limit yourself to the following options when sending instructions
680 meant to be executed by anyone running GNU patch, traditional patch,
681 or a patch that conforms to POSIX. Spaces are significant in the
682 following list, and operands are required.
683 -c
685 -d dir
686 -D define
687 -e
688 -l
689 -n
690 -N
691 -o outfile
692 -pnum
693 -R
694 -r rejectfile
695
697 Please report bugs via email to <bug-patch@gnu.org>.
698 If code has been duplicated (for instance with #ifdef OLDCODE ... #else
700 ... #endif), patch is incapable of patching both versions, and, if it
701 works at all, will likely patch the wrong one, and tell you that it
702 succeeded to boot.
703 If you apply a patch you've already applied, patch thinks it is a
705 reversed patch, and offers to un-apply the patch. This could be con‐
706 strued as a feature.
707 Computing how to merge a hunk is significantly harder than using the
709 standard fuzzy algorithm. Bigger hunks, more context, a bigger offset
710 from the original location, and a worse match all slow the algorithm
711 down.
712
714 Copyright (C) 1984, 1985, 1986, 1988 Larry Wall.
715 Copyright (C) 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997,
716 1998, 1999, 2000, 2001, 2002, 2009 Free Software Foundation, Inc.
717 Permission is granted to make and distribute verbatim copies of this
719 manual provided the copyright notice and this permission notice are
720 preserved on all copies.
721 Permission is granted to copy and distribute modified versions of this
723 manual under the conditions for verbatim copying, provided that the
724 entire resulting derived work is distributed under the terms of a per‐
725 mission notice identical to this one.
726 Permission is granted to copy and distribute translations of this man‐
728 ual into another language, under the above conditions for modified ver‐
729 sions, except that this permission notice may be included in transla‐
730 tions approved by the copyright holders instead of in the original Eng‐
731 lish.
732
734 Larry Wall wrote the original version of patch. Paul Eggert removed
735 patch's arbitrary limits; added support for binary files, setting file
736 times, and deleting files; and made it conform better to POSIX. Other
737 contributors include Wayne Davison, who added unidiff support, and
738 David MacKenzie, who added configuration and backup support. Andreas
739 Grünbacher added support for merging.
740 GNU PATCH(1)