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patch.1 (20410B)

      1 .\"-
      2 .\" Copyright 1986, Larry Wall
      3 .\"
      4 .\" Redistribution and use in source and binary forms, with or without
      5 .\" modification, are permitted provided that the following condition
      6 .\" is met:
      7 .\"  1. Redistributions of source code must retain the above copyright
      8 .\"     notice, this condition and the following disclaimer.
      9 .\"
     20 .\" SUCH DAMAGE.
     21 .\"
     22 .\" $OpenBSD: patch.1,v 1.26 2010/09/03 11:09:29 jmc Exp $
     23 .\" $FreeBSD$
     24 .Dd January 29, 2013
     25 .Dt PATCH 1
     26 .Os
     27 .Sh NAME
     28 .Nm patch
     29 .Nd apply a diff file to an original
     30 .Sh SYNOPSIS
     31 .Nm
     32 .Bk -words
     33 .Op Fl bCcEeflNnRstuv
     34 .Op Fl B Ar backup-prefix
     35 .Op Fl D Ar symbol
     36 .Op Fl d Ar directory
     37 .Op Fl F Ar max-fuzz
     38 .Op Fl i Ar patchfile
     39 .Op Fl o Ar out-file
     40 .Op Fl p Ar strip-count
     41 .Op Fl r Ar rej-name
     42 .Op Fl V Cm t | nil | never
     43 .Op Fl x Ar number
     44 .Op Fl z Ar backup-ext
     45 .Op Fl Fl posix
     46 .Op Ar origfile Op Ar patchfile
     47 .Ek
     48 .Nm
     49 .Pf \*(Lt Ar patchfile
     51 .Nm
     52 will take a patch file containing any of the four forms of difference
     53 listing produced by the
     54 .Xr diff 1
     55 program and apply those differences to an original file,
     56 producing a patched version.
     57 If
     58 .Ar patchfile
     59 is omitted, or is a hyphen, the patch will be read from the standard input.
     60 .Pp
     61 .Nm
     62 will attempt to determine the type of the diff listing, unless overruled by a
     63 .Fl c ,
     64 .Fl e ,
     65 .Fl n ,
     66 or
     67 .Fl u
     68 option.
     69 Context diffs (old-style, new-style, and unified) and
     70 normal diffs are applied directly by the
     71 .Nm
     72 program itself, whereas ed diffs are simply fed to the
     73 .Xr ed 1
     74 editor via a pipe.
     75 .Pp
     76 If the
     77 .Ar patchfile
     78 contains more than one patch,
     79 .Nm
     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
     86 below).
     87 .Pp
     88 The options are as follows:
     89 .Bl -tag -width Ds
     90 .It Xo
     91 .Fl B Ar backup-prefix ,
     92 .Fl Fl prefix Ar backup-prefix
     93 .Xc
     94 Causes the next argument to be interpreted as a prefix to the backup file
     95 name.
     96 If this argument is specified, any argument to
     97 .Fl z
     98 will be ignored.
     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
    102 .Qq .orig
    103 unless the file already has a numbered backup, in which case a numbered
    104 backup is made.
    105 This is equivalent to specifying
    106 .Qo Fl V Cm existing Qc .
    107 This option is currently the default, unless
    108 .Fl -posix
    109 is specified.
    110 .It Fl C , Fl Fl check
    111 Checks that the patch would apply cleanly, but does not modify anything.
    112 .It Fl c , Fl Fl context
    113 Forces
    114 .Nm
    115 to interpret the patch file as a context diff.
    116 .It Xo
    117 .Fl D Ar symbol ,
    118 .Fl Fl ifdef Ar symbol
    119 .Xc
    120 Causes
    121 .Nm
    122 to use the
    123 .Qq #ifdef...#endif
    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
    127 .Fl D
    128 and the argument.
    129 .It Xo
    130 .Fl d Ar directory ,
    131 .Fl Fl directory Ar directory
    132 .Xc
    133 Causes
    134 .Nm
    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
    138 Causes
    139 .Nm
    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.
    142 .It Fl e , Fl Fl ed
    143 Forces
    144 .Nm
    145 to interpret the patch file as an
    146 .Xr ed 1
    147 script.
    148 .It Xo
    149 .Fl F Ar max-fuzz ,
    150 .Fl Fl fuzz Ar max-fuzz
    151 .Xc
    152 Sets the maximum fuzz factor.
    153 This option only applies to context diffs, and causes
    154 .Nm
    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
    160 Forces
    161 .Nm
    162 to assume that the user knows exactly what he or she is doing, and to not
    163 ask any questions.
    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
    167 .Qq Prereq:
    168 line in the patch;
    169 and assume that patches are not reversed even if they look like they are.
    170 This option does not suppress commentary; use
    171 .Fl s
    172 for that.
    173 .It Xo
    174 .Fl i Ar patchfile ,
    175 .Fl Fl input Ar patchfile
    176 .Xc
    177 Causes the next argument to be interpreted as the input file name
    178 (i.e. a patchfile).
    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
    184 in the input file.
    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
    188 Causes
    189 .Nm
    190 to ignore patches that it thinks are reversed or already applied.
    191 See also
    192 .Fl R .
    193 .It Fl n , Fl Fl normal
    194 Forces
    195 .Nm
    196 to interpret the patch file as a normal diff.
    197 .It Xo
    198 .Fl o Ar out-file ,
    199 .Fl Fl output Ar out-file
    200 .Xc
    201 Causes the next argument to be interpreted as the output file name.
    202 .It Xo
    203 .Fl p Ar strip-count ,
    204 .Fl Fl strip Ar strip-count
    205 .Xc
    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
    209 out the patch.
    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 :
    215 .Pp
    216 Setting
    217 .Fl p Ns Ar 0
    218 gives the entire pathname unmodified.
    219 .Pp
    220 .Fl p Ns Ar 1
    221 gives
    222 .Pp
    223 .D1 Pa u/howard/src/blurfl/blurfl.c
    224 .Pp
    225 without the leading slash.
    226 .Pp
    227 .Fl p Ns Ar 4
    228 gives
    229 .Pp
    230 .D1 Pa blurfl/blurfl.c
    231 .Pp
    232 Not specifying
    233 .Fl p
    234 at all just gives you
    235 .Pa blurfl.c ,
    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
    242 .Fl d
    243 option.
    244 .It Fl R , Fl Fl reverse
    245 Tells
    246 .Nm
    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
    249 is.)
    250 .Nm
    251 will attempt to swap each hunk around before applying it.
    252 Rejects will come out in the swapped format.
    253 The
    254 .Fl R
    255 option will not work with ed diff scripts because there is too little
    256 information to reconstruct the reverse operation.
    257 .Pp
    258 If the first hunk of a patch fails,
    259 .Nm
    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
    262 .Fl R
    263 option set.
    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
    268 anywhere.
    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
    271 the heuristic.)
    272 .It Xo
    273 .Fl r Ar rej-name ,
    274 .Fl Fl reject-file Ar rej-name
    275 .Xc
    276 Causes the next argument to be interpreted as the reject file name.
    277 .It Xo
    278 .Fl s , Fl Fl quiet ,
    279 .Fl Fl silent
    280 .Xc
    281 Makes
    282 .Nm
    283 do its work silently, unless an error occurs.
    284 .It Fl t , Fl Fl batch
    285 Similar to
    286 .Fl f ,
    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
    289 .Fl f ) ;
    290 skip patches for which the file has the wrong version for the
    291 .Qq Prereq:
    292 line in the patch;
    293 and assume that patches are reversed if they look like they are.
    294 .It Fl u , Fl Fl unified
    295 Forces
    296 .Nm
    297 to interpret the patch file as a unified context diff (a unidiff).
    298 .It Xo
    299 .Fl V Cm t | nil | never ,
    300 .Fl Fl version-control Cm t | nil | never
    301 .Xc
    302 Causes the next argument to be interpreted as a method for creating
    303 backup file names.
    304 The type of backups made can also be given in the
    306 or
    308 environment variables, which are overridden by this option.
    309 The
    310 .Fl B
    311 option overrides this option, causing the prefix to always be used for
    312 making backup file names.
    313 The values of the
    315 and
    317 environment variables and the argument to the
    318 .Fl V
    319 option are like the GNU Emacs
    320 .Dq version-control
    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
    324 .It Cm t , numbered
    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.
    331 .El
    332 .It Fl v , Fl Fl version
    333 Causes
    334 .Nm
    335 to print out its revision header and patch level.
    336 .It Xo
    337 .Fl x Ar number ,
    338 .Fl Fl debug Ar number
    339 .Xc
    340 Sets internal debugging flags, and is of interest only to
    341 .Nm
    342 patchers.
    343 .It Xo
    344 .Fl z Ar backup-ext ,
    345 .Fl Fl suffix Ar backup-ext
    346 .Xc
    347 Causes the next argument to be interpreted as the backup extension, to be
    348 used in place of
    349 .Qq .orig .
    350 .It Fl Fl posix
    351 Enables strict
    352 .St -p1003.1-2008
    353 conformance, specifically:
    354 .Bl -enum
    355 .It
    356 Backup files are not created unless the
    357 .Fl b
    358 option is specified.
    359 .It
    360 If unspecified, the file name used is the first of the old, new and
    361 index files that exists.
    362 .El
    363 .El
    364 .Ss Patch Application
    365 .Nm
    366 will try to skip any leading garbage, apply the diff,
    367 and then skip any trailing garbage.
    368 Thus you could feed an article or message containing a
    369 diff listing to
    370 .Nm ,
    371 and it should work.
    372 If the entire diff is indented by a consistent amount,
    373 this will be taken into account.
    374 .Pp
    375 With context diffs, and to a lesser extent with normal diffs,
    376 .Nm
    377 can detect when the line numbers mentioned in the patch are incorrect,
    378 and will attempt to find the correct place to apply each hunk of the patch.
    379 As a first guess, it takes the line number mentioned for the hunk, plus or
    380 minus any offset used in applying the previous hunk.
    381 If that is not the correct place,
    382 .Nm
    383 will scan both forwards and backwards for a set of lines matching the context
    384 given in the hunk.
    385 First
    386 .Nm
    387 looks for a place where all lines of the context match.
    388 If no such place is found, and it's a context diff, and the maximum fuzz factor
    389 is set to 1 or more, then another scan takes place ignoring the first and last
    390 line of context.
    391 If that fails, and the maximum fuzz factor is set to 2 or more,
    392 the first two and last two lines of context are ignored,
    393 and another scan is made.
    394 .Pq The default maximum fuzz factor is 2.
    395 .Pp
    396 If
    397 .Nm
    398 cannot find a place to install that hunk of the patch, it will put the hunk
    399 out to a reject file, which normally is the name of the output file plus
    400 .Qq .rej .
    401 (Note that the rejected hunk will come out in context diff form whether the
    402 input patch was a context diff or a normal diff.
    403 If the input was a normal diff, many of the contexts will simply be null.)
    404 The line numbers on the hunks in the reject file may be different than
    405 in the patch file: they reflect the approximate location patch thinks the
    406 failed hunks belong in the new file rather than the old one.
    407 .Pp
    408 As each hunk is completed, you will be told whether the hunk succeeded or
    409 failed, and which line (in the new file)
    410 .Nm
    411 thought the hunk should go on.
    412 If this is different from the line number specified in the diff,
    413 you will be told the offset.
    414 A single large offset MAY be an indication that a hunk was installed in the
    415 wrong place.
    416 You will also be told if a fuzz factor was used to make the match, in which
    417 case you should also be slightly suspicious.
    418 .Ss Filename Determination
    419 If no original file is specified on the command line,
    420 .Nm
    421 will try to figure out from the leading garbage what the name of the file
    422 to edit is.
    423 When checking a prospective file name, pathname components are stripped
    424 as specified by the
    425 .Fl p
    426 option and the file's existence and writability are checked relative
    427 to the current working directory (or the directory specified by the
    428 .Fl d
    429 option).
    430 .Pp
    431 If the diff is a context or unified diff,
    432 .Nm
    433 is able to determine the old and new file names from the diff header.
    434 For context diffs, the
    435 .Dq old
    436 file is specified in the line beginning with
    437 .Qq ***
    438 and the
    439 .Dq new
    440 file is specified in the line beginning with
    441 .Qq --- .
    442 For a unified diff, the
    443 .Dq old
    444 file is specified in the line beginning with
    445 .Qq ---
    446 and the
    447 .Dq new
    448 file is specified in the line beginning with
    449 .Qq +++ .
    450 If there is an
    451 .Qq Index:
    452 line in the leading garbage (regardless of the diff type),
    453 .Nm
    454 will use the file name from that line as the
    455 .Dq index
    456 file.
    457 .Pp
    458 .Nm
    459 will choose the file name by performing the following steps, with the first
    460 match used:
    461 .Bl -enum
    462 .It
    463 If
    464 .Nm
    465 is operating in strict
    466 .St -p1003.1-2008
    467 mode, the first of the
    468 .Dq old ,
    469 .Dq new
    470 and
    471 .Dq index
    472 file names that exist is used.
    473 Otherwise,
    474 .Nm
    475 will examine either the
    476 .Dq old
    477 and
    478 .Dq new
    479 file names or, for a non-context diff, the
    480 .Dq index
    481 file name, and choose the file name with the fewest path components,
    482 the shortest basename, and the shortest total file name length (in that order).
    483 .It
    484 If no file exists,
    485 .Nm
    486 checks for the existence of the files in an SCCS or RCS directory
    487 (using the appropriate prefix or suffix) using the criteria specified
    488 above.
    489 If found,
    490 .Nm
    491 will attempt to get or check out the file.
    492 .It
    493 If no suitable file was found to patch, the patch file is a context or
    494 unified diff, and the old file was zero length, the new file name is
    495 created and used.
    496 .It
    497 If the file name still cannot be determined,
    498 .Nm
    499 will prompt the user for the file name to use.
    500 .El
    501 .Pp
    502 Additionally, if the leading garbage contains a
    503 .Qq Prereq:\ \&
    504 line,
    505 .Nm
    506 will take the first word from the prerequisites line (normally a version
    507 number) and check the input file to see if that word can be found.
    508 If not,
    509 .Nm
    510 will ask for confirmation before proceeding.
    511 .Pp
    512 The upshot of all this is that you should be able to say, while in a news
    513 interface, the following:
    514 .Pp
    515 .Dl | patch -d /usr/src/local/blurfl
    516 .Pp
    517 and patch a file in the blurfl directory directly from the article containing
    518 the patch.
    519 .Ss Backup Files
    520 By default, the patched version is put in place of the original, with
    521 the original file backed up to the same name with the extension
    522 .Qq .orig ,
    523 or as specified by the
    524 .Fl B ,
    525 .Fl V ,
    526 or
    527 .Fl z
    528 options.
    529 The extension used for making backup files may also be specified in the
    531 environment variable, which is overridden by the options above.
    532 .Pp
    533 If the backup file is a symbolic or hard link to the original file,
    534 .Nm
    535 creates a new backup file name by changing the first lowercase letter
    536 in the last component of the file's name into uppercase.
    537 If there are no more lowercase letters in the name,
    538 it removes the first character from the name.
    539 It repeats this process until it comes up with a
    540 backup file that does not already exist or is not linked to the original file.
    541 .Pp
    542 You may also specify where you want the output to go with the
    543 .Fl o
    544 option; if that file already exists, it is backed up first.
    545 .Ss Notes For Patch Senders
    546 There are several things you should bear in mind if you are going to
    547 be sending out patches:
    548 .Pp
    549 First, you can save people a lot of grief by keeping a
    550 .Pa patchlevel.h
    551 file which is patched to increment the patch level as the first diff in the
    552 patch file you send out.
    553 If you put a
    554 .Qq Prereq:
    555 line in with the patch, it will not let them apply
    556 patches out of order without some warning.
    557 .Pp
    558 Second, make sure you have specified the file names right, either in a
    559 context diff header, or with an
    560 .Qq Index:
    561 line.
    562 If you are patching something in a subdirectory, be sure to tell the patch
    563 user to specify a
    564 .Fl p
    565 option as needed.
    566 .Pp
    567 Third, you can create a file by sending out a diff that compares a
    568 null file to the file you want to create.
    569 This will only work if the file you want to create does not exist already in
    570 the target directory.
    571 .Pp
    572 Fourth, take care not to send out reversed patches, since it makes people wonder
    573 whether they already applied the patch.
    574 .Pp
    575 Fifth, while you may be able to get away with putting 582 diff listings into
    576 one file, it is probably wiser to group related patches into separate files in
    577 case something goes haywire.
    579 .Bl -tag -width "PATCH_VERSION_CONTROL" -compact
    581 When set,
    582 .Nm
    583 behaves as if the
    584 .Fl Fl posix
    585 option has been specified.
    587 Extension to use for backup file names instead of
    588 .Qq .orig .
    589 .It Ev TMPDIR
    590 Directory to put temporary files in; default is
    591 .Pa /tmp .
    593 Selects when numbered backup files are made.
    595 Same as
    597 .El
    598 .Sh FILES
    599 .Bl -tag -width "$TMPDIR/patch*" -compact
    600 .It Pa $TMPDIR/patch*
    601 .Nm
    602 temporary files
    603 .It Pa /dev/tty
    604 used to read input when
    605 .Nm
    606 prompts the user
    607 .El
    608 .Sh EXIT STATUS
    609 The
    610 .Nm
    611 utility exits with one of the following values:
    612 .Pp
    613 .Bl -tag -width Ds -offset indent -compact
    614 .It 0
    615 Successful completion.
    616 .It 1
    617 One or more lines were written to a reject file.
    618 .It \*(Gt1
    619 An error occurred.
    620 .El
    621 .Pp
    622 When applying a set of patches in a loop it behooves you to check this
    623 exit status so you do not apply a later patch to a partially patched file.
    625 Too many to list here, but generally indicative that
    626 .Nm
    627 couldn't parse your patch file.
    628 .Pp
    629 The message
    630 .Qq Hmm...
    631 indicates that there is unprocessed text in the patch file and that
    632 .Nm
    633 is attempting to intuit whether there is a patch in that text and, if so,
    634 what kind of patch it is.
    635 .Sh SEE ALSO
    636 .Xr diff 1
    637 .Sh STANDARDS
    638 The
    639 .Nm
    640 utility is compliant with the
    641 .St -p1003.1-2008
    642 specification
    643 (except as detailed above for the
    644 .Fl -posix
    645 option),
    646 though the presence of
    647 .Nm
    648 itself is optional.
    649 .Pp
    650 The flags
    651 .Op Fl BCEFfstVvxz
    652 and
    653 .Op Fl -posix
    654 are extensions to that specification.
    655 .Sh AUTHORS
    656 .An Larry Wall
    657 with many other contributors.
    658 .Sh CAVEATS
    659 .Nm
    660 cannot tell if the line numbers are off in an ed script, and can only detect
    661 bad line numbers in a normal diff when it finds a
    662 .Qq change
    663 or a
    664 .Qq delete
    665 command.
    666 A context diff using fuzz factor 3 may have the same problem.
    667 Until a suitable interactive interface is added, you should probably do
    668 a context diff in these cases to see if the changes made sense.
    669 Of course, compiling without errors is a pretty good indication that the patch
    670 worked, but not always.
    671 .Pp
    672 .Nm
    673 usually produces the correct results, even when it has to do a lot of
    674 guessing.
    675 However, the results are guaranteed to be correct only when the patch is
    676 applied to exactly the same version of the file that the patch was
    677 generated from.
    678 .Sh BUGS
    679 Could be smarter about partial matches, excessively deviant offsets and
    680 swapped code, but that would take an extra pass.
    681 .Pp
    682 Check patch mode
    683 .Pq Fl C
    684 will fail if you try to check several patches in succession that build on
    685 each other.
    686 The entire
    687 .Nm
    688 code would have to be restructured to keep temporary files around so that it
    689 can handle this situation.
    690 .Pp
    691 If code has been duplicated (for instance with #ifdef OLDCODE ... #else ...
    692 #endif),
    693 .Nm
    694 is incapable of patching both versions, and, if it works at all, will likely
    695 patch the wrong one, and tell you that it succeeded to boot.
    696 .Pp
    697 If you apply a patch you have already applied,
    698 .Nm
    699 will think it is a reversed patch, and offer to un-apply the patch.
    700 This could be construed as a feature.