2 .\" Copyright 1986, Larry Wall
4 .\" Redistribution and use in source and binary forms, with or without
5 .\" modification, are permitted provided that the following condition
7 .\" 1. Redistributions of source code must retain the above copyright
8 .\" notice, this condition and the following disclaimer.
10 .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
11 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
12 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
13 .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
14 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
15 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
16 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
17 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
18 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
19 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
22 .\" $OpenBSD: patch.1,v 1.27 2014/04/15 06:26:54 jmc Exp $
23 .\" $FreeBSD: head/usr.bin/patch/patch.1 354328 2019-11-04 03:07:01Z kevans $
29 .Nd apply a diff file to an original
34 .Op Fl B Ar backup-prefix
40 .Op Fl p Ar strip-count
42 .Op Fl V Cm t | nil | never | none
44 .Op Fl z Ar backup-ext
46 .Op Ar origfile Op Ar patchfile
49 .Pf \*(Lt Ar patchfile
52 will take a patch file containing any of the four forms of difference
53 listing produced by the
55 program and apply those differences to an original file,
56 producing a patched version.
59 is omitted, or is a hyphen, the patch will be read from the standard input.
62 will attempt to determine the type of the diff listing, unless overruled by a
69 Context diffs (old-style, new-style, and unified) and
70 normal diffs are applied directly by the
72 program itself, whereas ed diffs are simply fed to the
78 contains more than one patch,
80 will try to apply each of them as if they came from separate patch files.
81 This means, among other things, that it is assumed that the name of the file
82 to patch must be determined for each diff listing, and that the garbage before
83 each diff listing will be examined for interesting things such as file names
84 and revision level (see the section on
85 .Sx Filename Determination
88 The options are as follows:
91 .Fl B Ar backup-prefix ,
92 .Fl Fl prefix Ar backup-prefix
94 Causes the next argument to be interpreted as a prefix to the backup file
96 If this argument is specified, any argument to
99 .It Fl b , Fl Fl backup
100 Save a backup copy of the file before it is modified.
101 By default the original file is saved with a backup extension of
103 unless the file already has a numbered backup, in which case a numbered
105 This is equivalent to specifying
106 .Qo Fl V Cm existing Qc .
107 This option is currently the default, unless
110 .It Fl C , Fl Fl check , Fl Fl dry-run
111 Checks that the patch would apply cleanly, but does not modify anything.
112 .It Fl c , Fl Fl context
115 to interpret the patch file as a context diff.
118 .Fl Fl ifdef Ar symbol
124 construct to mark changes.
125 The argument following will be used as the differentiating symbol.
126 Note that, unlike the C compiler, there must be a space between the
131 .Fl Fl directory Ar directory
135 to interpret the next argument as a directory,
136 and change the working directory to it before doing anything else.
137 .It Fl E , Fl Fl remove-empty-files
140 to remove output files that are empty after the patches have been applied.
141 This option is useful when applying patches that create or remove files.
145 to interpret the patch file as an
150 .Fl Fl fuzz Ar max-fuzz
152 Sets the maximum fuzz factor.
153 This option only applies to context diffs, and causes
155 to ignore up to that many lines in looking for places to install a hunk.
156 Note that a larger fuzz factor increases the odds of a faulty patch.
157 The default fuzz factor is 2, and it may not be set to more than
158 the number of lines of context in the context diff, ordinarily 3.
159 .It Fl f , Fl Fl force
162 to assume that the user knows exactly what he or she is doing, and to not
164 It assumes the following:
165 skip patches for which a file to patch cannot be found;
166 patch files even though they have the wrong version for the
169 and assume that patches are not reversed even if they look like they are.
170 This option does not suppress commentary; use
175 .Fl Fl input Ar patchfile
177 Causes the next argument to be interpreted as the input file name
179 This option may be specified multiple times.
180 .It Fl l , Fl Fl ignore-whitespace
181 Causes the pattern matching to be done loosely, in case the tabs and
182 spaces have been munged in your input file.
183 Any sequence of whitespace in the pattern line will match any sequence
185 Normal characters must still match exactly.
186 Each line of the context must still match a line in the input file.
187 .It Fl N , Fl Fl forward
190 to ignore patches that it thinks are reversed or already applied.
193 .It Fl n , Fl Fl normal
196 to interpret the patch file as a normal diff.
199 .Fl Fl output Ar out-file
201 Causes the next argument to be interpreted as the output file name.
203 .Fl p Ar strip-count ,
204 .Fl Fl strip Ar strip-count
206 Sets the pathname strip count,
207 which controls how pathnames found in the patch file are treated,
208 in case you keep your files in a different directory than the person who sent
210 The strip count specifies how many slashes are to be stripped from
211 the front of the pathname.
212 (Any intervening directory names also go away.)
213 For example, supposing the file name in the patch file was
214 .Pa /u/howard/src/blurfl/blurfl.c :
218 gives the entire pathname unmodified.
223 .D1 Pa u/howard/src/blurfl/blurfl.c
225 without the leading slash.
230 .D1 Pa blurfl/blurfl.c
234 at all just gives you
236 unless all of the directories in the leading path
237 .Pq Pa u/howard/src/blurfl
238 exist and that path is relative,
239 in which case you get the entire pathname unmodified.
240 Whatever you end up with is looked for either in the current directory,
241 or the directory specified by the
244 .It Fl R , Fl Fl reverse
247 that this patch was created with the old and new files swapped.
248 (Yes, I'm afraid that does happen occasionally, human nature being what it
251 will attempt to swap each hunk around before applying it.
252 Rejects will come out in the swapped format.
255 option will not work with ed diff scripts because there is too little
256 information to reconstruct the reverse operation.
258 If the first hunk of a patch fails,
260 will reverse the hunk to see if it can be applied that way.
261 If it can, you will be asked if you want to have the
264 If it cannot, the patch will continue to be applied normally.
265 (Note: this method cannot detect a reversed patch if it is a normal diff
266 and if the first command is an append (i.e. it should have been a delete)
267 since appends always succeed, due to the fact that a null context will match
269 Luckily, most patches add or change lines rather than delete them, so most
270 reversed normal diffs will begin with a delete, which will fail, triggering
274 .Fl Fl reject-file Ar rej-name
276 Causes the next argument to be interpreted as the reject file name.
278 .Fl s , Fl Fl quiet ,
283 do its work silently, unless an error occurs.
284 .It Fl t , Fl Fl batch
287 in that it suppresses questions, but makes some different assumptions:
288 skip patches for which a file to patch cannot be found (the same as
290 skip patches for which the file has the wrong version for the
293 and assume that patches are reversed if they look like they are.
294 .It Fl u , Fl Fl unified
297 to interpret the patch file as a unified context diff (a unidiff).
299 .Fl V Cm t | nil | never | none ,
300 .Fl Fl version-control Cm t | nil | never | none
302 Causes the next argument to be interpreted as a method for creating
304 The type of backups made can also be given in the
305 .Ev PATCH_VERSION_CONTROL
308 environment variables, which are overridden by this option.
311 option overrides this option, causing the prefix to always be used for
312 making backup file names.
314 .Ev PATCH_VERSION_CONTROL
317 environment variables and the argument to the
319 option are like the GNU Emacs
321 variable; they also recognize synonyms that are more descriptive.
322 The valid values are (unique abbreviations are accepted):
323 .Bl -tag -width Ds -offset indent
325 Always make numbered backups.
326 .It Cm nil , existing
327 Make numbered backups of files that already have them,
328 simple backups of the others.
329 .It Cm never , simple
330 Always make simple backups.
334 .It Fl v , Fl Fl version
337 to print out its revision header and patch level.
340 .Fl Fl debug Ar number
342 Sets internal debugging flags, and is of interest only to
346 .Fl z Ar backup-ext ,
347 .Fl Fl suffix Ar backup-ext
349 Causes the next argument to be interpreted as the backup extension, to be
355 conformance, specifically:
358 Backup files are not created unless the
362 If unspecified, the file name used is the first of the old, new and
363 index files that exists.
366 .Ss Patch Application
368 will try to skip any leading garbage, apply the diff,
369 and then skip any trailing garbage.
370 Thus you could feed an article or message containing a
374 If the entire diff is indented by a consistent amount,
375 this will be taken into account.
377 With context diffs, and to a lesser extent with normal diffs,
379 can detect when the line numbers mentioned in the patch are incorrect,
380 and will attempt to find the correct place to apply each hunk of the patch.
381 As a first guess, it takes the line number mentioned for the hunk, plus or
382 minus any offset used in applying the previous hunk.
383 If that is not the correct place,
385 will scan both forwards and backwards for a set of lines matching the context
389 looks for a place where all lines of the context match.
390 If no such place is found, and it's a context diff, and the maximum fuzz factor
391 is set to 1 or more, then another scan takes place ignoring the first and last
393 If that fails, and the maximum fuzz factor is set to 2 or more,
394 the first two and last two lines of context are ignored,
395 and another scan is made.
396 .Pq The default maximum fuzz factor is 2.
400 cannot find a place to install that hunk of the patch, it will put the hunk
401 out to a reject file, which normally is the name of the output file plus
403 (Note that the rejected hunk will come out in context diff form whether the
404 input patch was a context diff or a normal diff.
405 If the input was a normal diff, many of the contexts will simply be null.)
406 The line numbers on the hunks in the reject file may be different than
407 in the patch file: they reflect the approximate location patch thinks the
408 failed hunks belong in the new file rather than the old one.
410 As each hunk is completed, you will be told whether the hunk succeeded or
411 failed, and which line (in the new file)
413 thought the hunk should go on.
414 If this is different from the line number specified in the diff,
415 you will be told the offset.
416 A single large offset MAY be an indication that a hunk was installed in the
418 You will also be told if a fuzz factor was used to make the match, in which
419 case you should also be slightly suspicious.
420 .Ss Filename Determination
421 If no original file is specified on the command line,
423 will try to figure out from the leading garbage what the name of the file
425 When checking a prospective file name, pathname components are stripped
428 option and the file's existence and writability are checked relative
429 to the current working directory (or the directory specified by the
433 If the diff is a context or unified diff,
435 is able to determine the old and new file names from the diff header.
436 For context diffs, the
438 file is specified in the line beginning with
442 file is specified in the line beginning with
444 For a unified diff, the
446 file is specified in the line beginning with
450 file is specified in the line beginning with
454 line in the leading garbage (regardless of the diff type),
456 will use the file name from that line as the
461 will choose the file name by performing the following steps, with the first
467 is operating in strict
469 mode, the first of the
474 file names that exist is used.
477 will examine either the
481 file names or, for a non-context diff, the
483 file name, and choose the file name with the fewest path components,
484 the shortest basename, and the shortest total file name length (in that order).
486 If no suitable file was found to patch, the patch file is a context or
487 unified diff, and the old file was zero length, the new file name is
490 If the file name still cannot be determined,
492 will prompt the user for the file name to use.
495 Additionally, if the leading garbage contains a
499 will take the first word from the prerequisites line (normally a version
500 number) and check the input file to see if that word can be found.
503 will ask for confirmation before proceeding.
505 The upshot of all this is that you should be able to say, while in a news
506 interface, the following:
508 .Dl | patch -d /usr/src/local/blurfl
510 and patch a file in the blurfl directory directly from the article containing
513 By default, the patched version is put in place of the original, with
514 the original file backed up to the same name with the extension
516 or as specified by the
522 The extension used for making backup files may also be specified in the
523 .Ev SIMPLE_BACKUP_SUFFIX
524 environment variable, which is overridden by the options above.
526 If the backup file is a symbolic or hard link to the original file,
528 creates a new backup file name by changing the first lowercase letter
529 in the last component of the file's name into uppercase.
530 If there are no more lowercase letters in the name,
531 it removes the first character from the name.
532 It repeats this process until it comes up with a
533 backup file that does not already exist or is not linked to the original file.
535 You may also specify where you want the output to go with the
537 option; if that file already exists, it is backed up first.
538 .Ss Notes For Patch Senders
539 There are several things you should bear in mind if you are going to
540 be sending out patches:
542 First, you can save people a lot of grief by keeping a
544 file which is patched to increment the patch level as the first diff in the
545 patch file you send out.
548 line in with the patch, it will not let them apply
549 patches out of order without some warning.
551 Second, make sure you have specified the file names right, either in a
552 context diff header, or with an
555 If you are patching something in a subdirectory, be sure to tell the patch
560 Third, you can create a file by sending out a diff that compares a
561 null file to the file you want to create.
562 If the file you want to create already exists in the target directory when the
563 diff is applied, then
565 will identify the patch as potentially reversed and offer to reverse the patch.
567 Fourth, take care not to send out reversed patches, since it makes people wonder
568 whether they already applied the patch.
570 Fifth, while you may be able to get away with putting 582 diff listings into
571 one file, it is probably wiser to group related patches into separate files in
572 case something goes haywire.
574 .Bl -tag -width "PATCH_VERSION_CONTROL" -compact
575 .It Ev POSIXLY_CORRECT
580 option has been specified.
581 .It Ev SIMPLE_BACKUP_SUFFIX
582 Extension to use for backup file names instead of
585 Directory to put temporary files in; default is
587 .It Ev PATCH_VERSION_CONTROL
588 Selects when numbered backup files are made.
589 .It Ev VERSION_CONTROL
591 .Ev PATCH_VERSION_CONTROL .
594 .Bl -tag -width "$TMPDIR/patch*" -compact
595 .It Pa $TMPDIR/patch*
599 used to read input when
606 utility exits with one of the following values:
608 .Bl -tag -width Ds -offset indent -compact
610 Successful completion.
612 One or more lines were written to a reject file.
617 When applying a set of patches in a loop it behooves you to check this
618 exit status so you do not apply a later patch to a partially patched file.
620 Too many to list here, but generally indicative that
622 couldn't parse your patch file.
626 indicates that there is unprocessed text in the patch file and that
628 is attempting to intuit whether there is a patch in that text and, if so,
629 what kind of patch it is.
635 utility is compliant with the
638 except as detailed above for the
646 are extensions to that specification.
649 with many other contributors.
652 cannot tell if the line numbers are off in an ed script, and can only detect
653 bad line numbers in a normal diff when it finds a
658 A context diff using fuzz factor 3 may have the same problem.
659 Until a suitable interactive interface is added, you should probably do
660 a context diff in these cases to see if the changes made sense.
661 Of course, compiling without errors is a pretty good indication that the patch
662 worked, but not always.
665 usually produces the correct results, even when it has to do a lot of
667 However, the results are guaranteed to be correct only when the patch is
668 applied to exactly the same version of the file that the patch was
671 Could be smarter about partial matches, excessively deviant offsets and
672 swapped code, but that would take an extra pass.
676 will fail if you try to check several patches in succession that build on
680 code would have to be restructured to keep temporary files around so that it
681 can handle this situation.
683 If code has been duplicated (for instance with #ifdef OLDCODE ... #else ...
686 is incapable of patching both versions, and, if it works at all, will likely
687 patch the wrong one, and tell you that it succeeded to boot.
689 If you apply a patch you have already applied,
691 will think it is a reversed patch, and offer to un-apply the patch.
692 This could be construed as a feature.
projects / dragonfly.git / blob