1 .\" $OpenBSD: patch.1,v 1.17 2003/10/31 20:20:45 millert Exp $
2 .\" $DragonFly: src/usr.bin/patch/patch.1,v 1.6 2005/09/06 00:43:16 swildner Exp $
4 .\" Copyright 1986, Larry Wall
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29 .Nd apply a diff file to an original
33 .Op Ar origfile Op Ar patchfile
35 .Pf \*(Lt Ar patchfile
38 will take a patch file containing any of the four forms of difference
39 listing produced by the
41 program and apply those differences to an original file,
42 producing a patched version.
45 is omitted, or is a hyphen, the patch will be read from the standard input.
48 will attempt to determine the type of the diff listing, unless over-ruled by a
55 Context diffs (old-style, new-style, and unified) and
56 normal diffs are applied directly by the
58 program itself, whereas ed diffs are simply fed to the
64 contains more than one patch,
66 will try to apply each of them as if they came from separate patch files.
67 This means, among other things, that it is assumed that the name of the file
68 to patch must be determined for each diff listing, and that the garbage before
69 each diff listing will be examined for interesting things such as file names
70 and revision level (see the section on
71 .Sx Filename Determination
74 The options are as follows:
76 .It Fl b , Fl Fl backup
77 Save a backup copy of the file before it is modified.
78 By default the original file is saved with a backup extension of
80 unless the file already has a numbered backup, in which case a numbered
82 This is equivalent to specifying
83 .Qo Fl V Ar existing Qc .
84 This option is currently the default but that will change in a future release.
85 .It Fl B , Fl Fl prefix
86 Causes the next argument to be interpreted as a prefix to the backup file
88 If this argument is specified, any argument to
91 .It Fl c , Fl Fl context
94 to interpret the patch file as a context diff.
95 .It Fl C , Fl Fl check
96 Checks that the patch would apply cleanly, but does not modify anything.
97 .It Fl d , Fl Fl directory
100 to interpret the next argument as a directory, and
102 to it before doing anything else.
103 .It Fl D , Fl Fl ifdef
108 construct to mark changes.
109 The argument following will be used as the differentiating symbol.
110 Note that, unlike the C compiler, there must be a space between the
116 to interpret the patch file as an
119 .It Fl E , Fl Fl remove-empty-files
122 to remove output files that are empty after the patches have been applied.
123 This option is useful when applying patches that create or remove files.
124 .It Fl f , Fl Fl force
127 to assume that the user knows exactly what he or she is doing, and to not
129 It assumes the following:
130 skip patches for which a file to patch can't be found;
131 patch files even though they have the wrong version for the
134 and assume that patches are not reversed even if they look like they are.
135 This option does not suppress commentary; use
139 .Fl F Ns Aq Ar number ,
140 .Fl Fl fuzz Aq Ar number
142 Sets the maximum fuzz factor.
143 This option only applies to context diffs, and causes
145 to ignore up to that many lines in looking for places to install a hunk.
146 Note that a larger fuzz factor increases the odds of a faulty patch.
147 The default fuzz factor is 2, and it may not be set to more than
148 the number of lines of context in the context diff, ordinarily 3.
149 .It Fl i , Fl Fl input
150 Causes the next argument to be interpreted as the input file name
152 This option may be specified multiple times.
153 .It Fl l , Fl Fl ignore-whitespace
154 Causes the pattern matching to be done loosely, in case the tabs and
155 spaces have been munged in your input file.
156 Any sequence of whitespace in the pattern line will match any sequence
158 Normal characters must still match exactly.
159 Each line of the context must still match a line in the input file.
160 .It Fl n , Fl Fl normal
163 to interpret the patch file as a normal diff.
164 .It Fl N , Fl Fl forward
167 to ignore patches that it thinks are reversed or already applied.
170 .It Fl o , Fl Fl output
171 Causes the next argument to be interpreted as the output file name.
173 .Fl p Ns Aq Ar number ,
174 .Fl Fl strip Aq Ar number
176 Sets the pathname strip count,
177 which controls how pathnames found in the patch file are treated,
178 in case you keep your files in a different directory than the person who sent
180 The strip count specifies how many slashes are to be stripped from
181 the front of the pathname.
182 (Any intervening directory names also go away.)
183 For example, supposing the file name in the patch file was
184 .Pa /u/howard/src/blurfl/blurfl.c :
188 gives the entire pathname unmodified.
193 .D1 Pa u/howard/src/blurfl/blurfl.c
195 without the leading slash.
200 .D1 Pa blurfl/blurfl.c
204 at all just gives you
206 unless all of the directories in the leading path
207 .Pq Pa u/howard/src/blurfl
208 exist and that path is relative,
209 in which case you get the entire pathname unmodified.
210 Whatever you end up with is looked for either in the current directory,
211 or the directory specified by the
214 .It Fl r , Fl Fl reject-file
215 Causes the next argument to be interpreted as the reject file name.
216 .It Fl R , Fl Fl reverse
219 that this patch was created with the old and new files swapped.
220 (Yes, I'm afraid that does happen occasionally, human nature being what it
223 will attempt to swap each hunk around before applying it.
224 Rejects will come out in the swapped format.
227 option will not work with ed diff scripts because there is too little
228 information to reconstruct the reverse operation.
230 If the first hunk of a patch fails,
232 will reverse the hunk to see if it can be applied that way.
233 If it can, you will be asked if you want to have the
236 If it can't, the patch will continue to be applied normally.
237 (Note: this method cannot detect a reversed patch if it is a normal diff
238 and if the first command is an append (i.e. it should have been a delete)
239 since appends always succeed, due to the fact that a null context will match
241 Luckily, most patches add or change lines rather than delete them, so most
242 reversed normal diffs will begin with a delete, which will fail, triggering
245 .Fl s , Fl Fl quiet ,
250 do its work silently, unless an error occurs.
251 .It Fl t , Fl Fl batch
254 in that it suppresses questions, but makes some different assumptions:
255 skip patches for which a file to patch can't be found (the same as
257 skip patches for which the file has the wrong version for the
260 and assume that patches are reversed if they look like they are.
261 .It Fl u , Fl Fl unified
264 to interpret the patch file as a unified context diff (a unidiff).
265 .It Fl v , Fl Fl version
268 to print out its revision header and patch level.
269 .It Fl V , Fl Fl version-control
270 Causes the next argument to be interpreted as a method for creating
272 The type of backups made can also be given in the
273 .Ev PATCH_VERSION_CONTROL
276 environment variables, which are overridden by this option.
279 option overrides this option, causing the prefix to always be used for
280 making backup file names.
282 .Ev PATCH_VERSION_CONTROL
285 environment variables and the argument to the
287 option are like the GNU Emacs
289 variable; they also recognize synonyms that are more descriptive.
290 The valid values are (unique abbreviations are accepted):
291 .Bl -tag -width Ds -offset indent
293 Always make numbered backups.
295 Make numbered backups of files that already have them,
296 simple backups of the others.
298 Always make simple backups.
301 .Fl x Ns Aq Ar number ,
302 .Fl Fl debug Aq Ar number
304 Sets internal debugging flags, and is of interest only to
307 .It Fl z , Fl Fl suffix
308 Causes the next argument to be interpreted as the backup extension, to be
314 conformance, specifically:
317 Backup files are not created unless the
321 If unspecified, the file name used is the first of the old, new and
322 index files that exists.
325 .Ss Patch Application
327 will try to skip any leading garbage, apply the diff,
328 and then skip any trailing garbage.
329 Thus you could feed an article or message containing a
333 If the entire diff is indented by a consistent amount,
334 this will be taken into account.
336 With context diffs, and to a lesser extent with normal diffs,
338 can detect when the line numbers mentioned in the patch are incorrect,
339 and will attempt to find the correct place to apply each hunk of the patch.
340 As a first guess, it takes the line number mentioned for the hunk, plus or
341 minus any offset used in applying the previous hunk.
342 If that is not the correct place,
344 will scan both forwards and backwards for a set of lines matching the context
348 looks for a place where all lines of the context match.
349 If no such place is found, and it's a context diff, and the maximum fuzz factor
350 is set to 1 or more, then another scan takes place ignoring the first and last
352 If that fails, and the maximum fuzz factor is set to 2 or more,
353 the first two and last two lines of context are ignored,
354 and another scan is made.
355 .Pq The default maximum fuzz factor is 2.
359 cannot find a place to install that hunk of the patch, it will put the hunk
360 out to a reject file, which normally is the name of the output file plus
362 (Note that the rejected hunk will come out in context diff form whether the
363 input patch was a context diff or a normal diff.
364 If the input was a normal diff, many of the contexts will simply be null.)
365 The line numbers on the hunks in the reject file may be different than
366 in the patch file: they reflect the approximate location patch thinks the
367 failed hunks belong in the new file rather than the old one.
369 As each hunk is completed, you will be told whether the hunk succeeded or
370 failed, and which line (in the new file)
372 thought the hunk should go on.
373 If this is different from the line number specified in the diff,
374 you will be told the offset.
375 A single large offset MAY be an indication that a hunk was installed in the
377 You will also be told if a fuzz factor was used to make the match, in which
378 case you should also be slightly suspicious.
379 .Ss Filename Determination
380 If no original file is specified on the command line,
382 will try to figure out from the leading garbage what the name of the file
384 When checking a prospective file name, pathname components are stripped
387 option and the file's existence and writability are checked relative
388 to the current working directory (or the directory specified by the
392 If the diff is a context or unified diff,
394 is able to determine the old and new file names from the diff header.
395 For context diffs, the
397 file is specified in the line beginning with
401 file is specified in the line beginning with
403 For a unified diff, the
405 file is specified in the line beginning with
409 file is specified in the line beginning with
413 line in the leading garbage (regardless of the diff type),
415 will use the file name from that line as the
420 will choose the file name by performing the following steps, with the first
426 is operating in strict
428 mode, the first of the
433 file names that exist is used.
436 will examine either the
440 file names or, for a non-context diff, the
442 file name, and choose the file name with the fewest path components,
443 the shortest basename, and the shortest total file name length (in that order).
447 checks for the existence of the files in an SCCS or RCS directory
448 (using the appropriate prefix or suffix) using the criteria specified
452 will attempt to get or check out the file.
454 If no suitable file was found to patch, the patch file is a context or
455 unified diff, and the old file was zero length, the new file name is
458 If the file name still cannot be determined,
460 will prompt the user for the file name to use.
463 Additionally, if the leading garbage contains a
467 will take the first word from the prerequisites line (normally a version
468 number) and check the input file to see if that word can be found.
471 will ask for confirmation before proceeding.
473 The upshot of all this is that you should be able to say, while in a news
474 interface, the following:
476 .Dl | patch -d /usr/src/local/blurfl
478 and patch a file in the blurfl directory directly from the article containing
481 By default, the patched version is put in place of the original, with
482 the original file backed up to the same name with the extension
484 or as specified by the
490 The extension used for making backup files may also be specified in the
491 .Ev SIMPLE_BACKUP_SUFFIX
492 environment variable, which is overridden by the options above.
494 If the backup file is a symbolic or hard link to the original file,
496 creates a new backup file name by changing the first lowercase letter
497 in the last component of the file's name into uppercase.
498 If there are no more lowercase letters in the name,
499 it removes the first character from the name.
500 It repeats this process until it comes up with a
501 backup file that does not already exist or is not linked to the original file.
503 You may also specify where you want the output to go with the
505 option; if that file already exists, it is backed up first.
506 .Ss Notes For Patch Senders
507 There are several things you should bear in mind if you are going to
508 be sending out patches:
510 First, you can save people a lot of grief by keeping a
512 file which is patched to increment the patch level as the first diff in the
513 patch file you send out.
516 line in with the patch, it won't let them apply
517 patches out of order without some warning.
519 Second, make sure you've specified the file names right, either in a
520 context diff header, or with an
523 If you are patching something in a subdirectory, be sure to tell the patch
528 Third, you can create a file by sending out a diff that compares a
529 null file to the file you want to create.
530 This will only work if the file you want to create doesn't exist already in
531 the target directory.
533 Fourth, take care not to send out reversed patches, since it makes people wonder
534 whether they already applied the patch.
536 Fifth, while you may be able to get away with putting 582 diff listings into
537 one file, it is probably wiser to group related patches into separate files in
538 case something goes haywire.
540 .Bl -tag -width "PATCH_VERSION_CONTROL" -compact
541 .It Ev POSIXLY_CORRECT
546 option has been specified.
547 .It Ev SIMPLE_BACKUP_SUFFIX
548 Extension to use for backup file names instead of
551 Directory to put temporary files in; default is
553 .It Ev PATCH_VERSION_CONTROL
554 Selects when numbered backup files are made.
555 .It Ev VERSION_CONTROL
557 .Ev PATCH_VERSION_CONTROL .
560 .Bl -tag -width "$TMPDIR/patch*" -compact
561 .It Pa $TMPDIR/patch*
565 used to read input when
570 Too many to list here, but generally indicative that
572 couldn't parse your patch file.
576 indicates that there is unprocessed text in the patch file and that
578 is attempting to intuit whether there is a patch in that text and, if so,
579 what kind of patch it is.
583 utility exits with one of the following values:
585 .Bl -tag -width Ds -compact -offset indent
587 Successful completion.
589 One or more lines were written to a reject file.
594 When applying a set of patches in a loop it behooves you to check this
595 exit status so you don't apply a later patch to a partially patched file.
600 with many other contributors.
603 cannot tell if the line numbers are off in an ed script, and can only detect
604 bad line numbers in a normal diff when it finds a
609 A context diff using fuzz factor 3 may have the same problem.
610 Until a suitable interactive interface is added, you should probably do
611 a context diff in these cases to see if the changes made sense.
612 Of course, compiling without errors is a pretty good indication that the patch
613 worked, but not always.
616 usually produces the correct results, even when it has to do a lot of
618 However, the results are guaranteed to be correct only when the patch is
619 applied to exactly the same version of the file that the patch was
622 Could be smarter about partial matches, excessively deviant offsets and
623 swapped code, but that would take an extra pass.
627 will fail if you try to check several patches in succession that build on
631 code would have to be restructured to keep temporary files around so that it
632 can handle this situation.
634 If code has been duplicated (for instance with #ifdef OLDCODE ... #else ...
637 is incapable of patching both versions, and, if it works at all, will likely
638 patch the wrong one, and tell you that it succeeded to boot.
640 If you apply a patch you've already applied,
642 will think it is a reversed patch, and offer to un-apply the patch.
643 This could be construed as a feature.
mneumann's projects / dragonfly.git / blob