1 .\" $OpenBSD: patch.1,v 1.22 2008/06/06 20:44:00 jmc Exp $
2 .\" $DragonFly: src/usr.bin/patch/patch.1,v 1.10 2008/08/18 19:15:55 joerg Exp $
3 .\" Copyright 1986, Larry Wall
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28 .Nd apply a diff file to an original
33 .Op Fl B Ar backup-prefix
39 .Op Fl p Ar strip-count
41 .Op Fl V Cm t | nil | never
43 .Op Fl z Ar backup-ext
45 .Op Ar origfile Op Ar patchfile
48 .Pf \*(Lt Ar patchfile
51 will take a patch file containing any of the four forms of difference
52 listing produced by the
54 program and apply those differences to an original file,
55 producing a patched version.
58 is omitted, or is a hyphen, the patch will be read from the standard input.
61 will attempt to determine the type of the diff listing, unless over-ruled by a
68 Context diffs (old-style, new-style, and unified) and
69 normal diffs are applied directly by the
71 program itself, whereas ed diffs are simply fed to the
77 contains more than one patch,
79 will try to apply each of them as if they came from separate patch files.
80 This means, among other things, that it is assumed that the name of the file
81 to patch must be determined for each diff listing, and that the garbage before
82 each diff listing will be examined for interesting things such as file names
83 and revision level (see the section on
84 .Sx Filename Determination
87 The options are as follows:
90 .Fl B Ar backup-prefix ,
91 .Fl Fl prefix Ar backup-prefix
93 Causes the next argument to be interpreted as a prefix to the backup file
95 If this argument is specified, any argument to
98 .It Fl b , Fl Fl backup
99 Save a backup copy of the file before it is modified.
100 By default the original file is saved with a backup extension of
102 unless the file already has a numbered backup, in which case a numbered
104 This is equivalent to specifying
105 .Qo Fl V Cm existing Qc .
106 This option is currently the default, unless
109 .It Fl C , Fl Fl check
110 Checks that the patch would apply cleanly, but does not modify anything.
111 .It Fl c , Fl Fl context
114 to interpret the patch file as a context diff.
117 .Fl Fl ifdef Ar symbol
123 construct to mark changes.
124 The argument following will be used as the differentiating symbol.
125 Note that, unlike the C compiler, there must be a space between the
130 .Fl Fl directory Ar directory
134 to interpret the next argument as a directory,
135 and change the working directory to it before doing anything else.
136 .It Fl E , Fl Fl remove-empty-files
139 to remove output files that are empty after the patches have been applied.
140 This option is useful when applying patches that create or remove files.
144 to interpret the patch file as an
149 .Fl Fl fuzz Ar max-fuzz
151 Sets the maximum fuzz factor.
152 This option only applies to context diffs, and causes
154 to ignore up to that many lines in looking for places to install a hunk.
155 Note that a larger fuzz factor increases the odds of a faulty patch.
156 The default fuzz factor is 2, and it may not be set to more than
157 the number of lines of context in the context diff, ordinarily 3.
158 .It Fl f , Fl Fl force
161 to assume that the user knows exactly what he or she is doing, and to not
163 It assumes the following:
164 skip patches for which a file to patch can't be found;
165 patch files even though they have the wrong version for the
168 and assume that patches are not reversed even if they look like they are.
169 This option does not suppress commentary; use
174 .Fl Fl input Ar patchfile
176 Causes the next argument to be interpreted as the input file name
178 This option may be specified multiple times.
179 .It Fl l , Fl Fl ignore-whitespace
180 Causes the pattern matching to be done loosely, in case the tabs and
181 spaces have been munged in your input file.
182 Any sequence of whitespace in the pattern line will match any sequence
184 Normal characters must still match exactly.
185 Each line of the context must still match a line in the input file.
186 .It Fl N , Fl Fl forward
189 to ignore patches that it thinks are reversed or already applied.
192 .It Fl n , Fl Fl normal
195 to interpret the patch file as a normal diff.
198 .Fl Fl output Ar out-file
200 Causes the next argument to be interpreted as the output file name.
202 .Fl p Ar strip-count ,
203 .Fl Fl strip Ar strip-count
205 Sets the pathname strip count,
206 which controls how pathnames found in the patch file are treated,
207 in case you keep your files in a different directory than the person who sent
209 The strip count specifies how many slashes are to be stripped from
210 the front of the pathname.
211 (Any intervening directory names also go away.)
212 For example, supposing the file name in the patch file was
213 .Pa /u/howard/src/blurfl/blurfl.c :
217 gives the entire pathname unmodified.
222 .D1 Pa u/howard/src/blurfl/blurfl.c
224 without the leading slash.
229 .D1 Pa blurfl/blurfl.c
233 at all just gives you
235 unless all of the directories in the leading path
236 .Pq Pa u/howard/src/blurfl
237 exist and that path is relative,
238 in which case you get the entire pathname unmodified.
239 Whatever you end up with is looked for either in the current directory,
240 or the directory specified by the
243 .It Fl R , Fl Fl reverse
246 that this patch was created with the old and new files swapped.
247 (Yes, I'm afraid that does happen occasionally, human nature being what it
250 will attempt to swap each hunk around before applying it.
251 Rejects will come out in the swapped format.
254 option will not work with ed diff scripts because there is too little
255 information to reconstruct the reverse operation.
257 If the first hunk of a patch fails,
259 will reverse the hunk to see if it can be applied that way.
260 If it can, you will be asked if you want to have the
263 If it can't, the patch will continue to be applied normally.
264 (Note: this method cannot detect a reversed patch if it is a normal diff
265 and if the first command is an append (i.e. it should have been a delete)
266 since appends always succeed, due to the fact that a null context will match
268 Luckily, most patches add or change lines rather than delete them, so most
269 reversed normal diffs will begin with a delete, which will fail, triggering
273 .Fl Fl reject-file Ar rej-name
275 Causes the next argument to be interpreted as the reject file name.
277 .Fl s , Fl Fl quiet ,
282 do its work silently, unless an error occurs.
283 .It Fl t , Fl Fl batch
286 in that it suppresses questions, but makes some different assumptions:
287 skip patches for which a file to patch can't be found (the same as
289 skip patches for which the file has the wrong version for the
292 and assume that patches are reversed if they look like they are.
293 .It Fl u , Fl Fl unified
296 to interpret the patch file as a unified context diff (a unidiff).
298 .Fl V Cm t | nil | never ,
299 .Fl Fl version-control Cm t | nil | never
301 Causes the next argument to be interpreted as a method for creating
303 The type of backups made can also be given in the
304 .Ev PATCH_VERSION_CONTROL
307 environment variables, which are overridden by this option.
310 option overrides this option, causing the prefix to always be used for
311 making backup file names.
313 .Ev PATCH_VERSION_CONTROL
316 environment variables and the argument to the
318 option are like the GNU Emacs
320 variable; they also recognize synonyms that are more descriptive.
321 The valid values are (unique abbreviations are accepted):
322 .Bl -tag -width Ds -offset indent
324 Always make numbered backups.
325 .It Cm nil , existing
326 Make numbered backups of files that already have them,
327 simple backups of the others.
328 .It Cm never , simple
329 Always make simple backups.
331 .It Fl v , Fl Fl version
334 to print out its revision header and patch level.
337 .Fl Fl debug Ar number
339 Sets internal debugging flags, and is of interest only to
343 .Fl z Ar backup-ext ,
344 .Fl Fl suffix Ar backup-ext
346 Causes the next argument to be interpreted as the backup extension, to be
352 conformance, specifically:
355 Backup files are not created unless the
359 If unspecified, the file name used is the first of the old, new and
360 index files that exists.
363 .Ss Patch Application
365 will try to skip any leading garbage, apply the diff,
366 and then skip any trailing garbage.
367 Thus you could feed an article or message containing a
371 If the entire diff is indented by a consistent amount,
372 this will be taken into account.
374 With context diffs, and to a lesser extent with normal diffs,
376 can detect when the line numbers mentioned in the patch are incorrect,
377 and will attempt to find the correct place to apply each hunk of the patch.
378 As a first guess, it takes the line number mentioned for the hunk, plus or
379 minus any offset used in applying the previous hunk.
380 If that is not the correct place,
382 will scan both forwards and backwards for a set of lines matching the context
386 looks for a place where all lines of the context match.
387 If no such place is found, and it's a context diff, and the maximum fuzz factor
388 is set to 1 or more, then another scan takes place ignoring the first and last
390 If that fails, and the maximum fuzz factor is set to 2 or more,
391 the first two and last two lines of context are ignored,
392 and another scan is made.
393 .Pq The default maximum fuzz factor is 2.
397 cannot find a place to install that hunk of the patch, it will put the hunk
398 out to a reject file, which normally is the name of the output file plus
400 (Note that the rejected hunk will come out in context diff form whether the
401 input patch was a context diff or a normal diff.
402 If the input was a normal diff, many of the contexts will simply be null.)
403 The line numbers on the hunks in the reject file may be different than
404 in the patch file: they reflect the approximate location patch thinks the
405 failed hunks belong in the new file rather than the old one.
407 As each hunk is completed, you will be told whether the hunk succeeded or
408 failed, and which line (in the new file)
410 thought the hunk should go on.
411 If this is different from the line number specified in the diff,
412 you will be told the offset.
413 A single large offset MAY be an indication that a hunk was installed in the
415 You will also be told if a fuzz factor was used to make the match, in which
416 case you should also be slightly suspicious.
417 .Ss Filename Determination
418 If no original file is specified on the command line,
420 will try to figure out from the leading garbage what the name of the file
422 When checking a prospective file name, pathname components are stripped
425 option and the file's existence and writability are checked relative
426 to the current working directory (or the directory specified by the
430 If the diff is a context or unified diff,
432 is able to determine the old and new file names from the diff header.
433 For context diffs, the
435 file is specified in the line beginning with
439 file is specified in the line beginning with
441 For a unified diff, the
443 file is specified in the line beginning with
447 file is specified in the line beginning with
451 line in the leading garbage (regardless of the diff type),
453 will use the file name from that line as the
458 will choose the file name by performing the following steps, with the first
464 is operating in strict
466 mode, the first of the
471 file names that exist is used.
474 will examine either the
478 file names or, for a non-context diff, the
480 file name, and choose the file name with the fewest path components,
481 the shortest basename, and the shortest total file name length (in that order).
485 checks for the existence of the files in an SCCS or RCS directory
486 (using the appropriate prefix or suffix) using the criteria specified
490 will attempt to get or check out the file.
492 If no suitable file was found to patch, the patch file is a context or
493 unified diff, and the old file was zero length, the new file name is
496 If the file name still cannot be determined,
498 will prompt the user for the file name to use.
501 Additionally, if the leading garbage contains a
505 will take the first word from the prerequisites line (normally a version
506 number) and check the input file to see if that word can be found.
509 will ask for confirmation before proceeding.
511 The upshot of all this is that you should be able to say, while in a news
512 interface, the following:
514 .Dl | patch -d /usr/src/local/blurfl
516 and patch a file in the blurfl directory directly from the article containing
519 By default, the patched version is put in place of the original, with
520 the original file backed up to the same name with the extension
522 or as specified by the
528 The extension used for making backup files may also be specified in the
529 .Ev SIMPLE_BACKUP_SUFFIX
530 environment variable, which is overridden by the options above.
532 If the backup file is a symbolic or hard link to the original file,
534 creates a new backup file name by changing the first lowercase letter
535 in the last component of the file's name into uppercase.
536 If there are no more lowercase letters in the name,
537 it removes the first character from the name.
538 It repeats this process until it comes up with a
539 backup file that does not already exist or is not linked to the original file.
541 You may also specify where you want the output to go with the
543 option; if that file already exists, it is backed up first.
544 .Ss Notes For Patch Senders
545 There are several things you should bear in mind if you are going to
546 be sending out patches:
548 First, you can save people a lot of grief by keeping a
550 file which is patched to increment the patch level as the first diff in the
551 patch file you send out.
554 line in with the patch, it won't let them apply
555 patches out of order without some warning.
557 Second, make sure you've specified the file names right, either in a
558 context diff header, or with an
561 If you are patching something in a subdirectory, be sure to tell the patch
566 Third, you can create a file by sending out a diff that compares a
567 null file to the file you want to create.
568 This will only work if the file you want to create doesn't exist already in
569 the target directory.
571 Fourth, take care not to send out reversed patches, since it makes people wonder
572 whether they already applied the patch.
574 Fifth, while you may be able to get away with putting 582 diff listings into
575 one file, it is probably wiser to group related patches into separate files in
576 case something goes haywire.
578 .Bl -tag -width "PATCH_VERSION_CONTROL" -compact
579 .It Ev POSIXLY_CORRECT
584 option has been specified.
585 .It Ev SIMPLE_BACKUP_SUFFIX
586 Extension to use for backup file names instead of
589 Directory to put temporary files in; default is
591 .It Ev PATCH_VERSION_CONTROL
592 Selects when numbered backup files are made.
593 .It Ev VERSION_CONTROL
595 .Ev PATCH_VERSION_CONTROL .
598 .Bl -tag -width "$TMPDIR/patch*" -compact
599 .It Pa $TMPDIR/patch*
603 used to read input when
608 Too many to list here, but generally indicative that
610 couldn't parse your patch file.
614 indicates that there is unprocessed text in the patch file and that
616 is attempting to intuit whether there is a patch in that text and, if so,
617 what kind of patch it is.
621 utility exits with one of the following values:
623 .Bl -tag -width Ds -compact -offset indent
625 Successful completion.
627 One or more lines were written to a reject file.
632 When applying a set of patches in a loop it behooves you to check this
633 exit status so you don't apply a later patch to a partially patched file.
639 utility is compliant with the
642 (except as detailed above for the
645 though the presence of
653 are extensions to that specification.
656 with many other contributors.
659 cannot tell if the line numbers are off in an ed script, and can only detect
660 bad line numbers in a normal diff when it finds a
665 A context diff using fuzz factor 3 may have the same problem.
666 Until a suitable interactive interface is added, you should probably do
667 a context diff in these cases to see if the changes made sense.
668 Of course, compiling without errors is a pretty good indication that the patch
669 worked, but not always.
672 usually produces the correct results, even when it has to do a lot of
674 However, the results are guaranteed to be correct only when the patch is
675 applied to exactly the same version of the file that the patch was
678 Could be smarter about partial matches, excessively deviant offsets and
679 swapped code, but that would take an extra pass.
683 will fail if you try to check several patches in succession that build on
687 code would have to be restructured to keep temporary files around so that it
688 can handle this situation.
690 If code has been duplicated (for instance with #ifdef OLDCODE ... #else ...
693 is incapable of patching both versions, and, if it works at all, will likely
694 patch the wrong one, and tell you that it succeeded to boot.
696 If you apply a patch you've already applied,
698 will think it is a reversed patch, and offer to un-apply the patch.
699 This could be construed as a feature.
projects / dragonfly.git / blob