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Diff for /src/usr.bin/patch/patch.1 between version 1.8 and 1.9

version 1.8, 2003/07/22 20:17:06 version 1.9, 2003/07/24 04:41:19
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 .\"     $OpenBSD$       -*- nroff -*-  .\"     $OpenBSD$
 .\" Copyright 1986, Larry Wall  .\" Copyright 1986, Larry Wall
 .\"  .\"
 .\" Redistribution and use in source and binary forms, with or without  .\" Redistribution and use in source and binary forms, with or without
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 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF  .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.  .\" SUCH DAMAGE.
 .\"  .\"
 .rn '' }`  .Dd July 23, 2003
 .de Sh  .Dt PATCH 1
 .br  .Os
 .ne 5  .Sh NAME
 .PP  .Nm patch
 \fB\\$1\fR  .Nd apply a diff file to an original
 .PP  .Sh SYNOPSIS
 ..  .Nm patch
 .de Sp  .Op Cm options
 .if t .sp .5v  .Op Ar origfile Op Ar patchfile
 .if n .sp  .Nm patch
 ..  .Pf \*(Lt Ar patchfile
 '\"  .Sh DESCRIPTION
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 .TH PATCH 1  
 .SH NAME  
 patch - apply a diff file to an original  
 .SH SYNOPSIS  
 .B patch  
 [options] [origfile [patchfile]]  
 .sp  
 but usually just  
 .sp  
 .B patch  
 <patchfile  
 .SH DESCRIPTION  
 .I Patch  
 will take a patch file containing any of the four forms of difference  will take a patch file containing any of the four forms of difference
 listing produced by the  listing produced by the
 .I diff  .Xr diff 1
 program and apply those differences to an original file, producing a patched  program and apply those differences to an original file,
 version.  producing a patched version.
 By default, the patched version is put in place of the original, with  By default, the patched version is put in place of the original, with
 the original file backed up to the same name with the  the original file backed up to the same name with the extension
 extension \*(L".orig\*(R" (\*(L"~\*(R" on systems that do not  .Qq .orig
 support long filenames), or as specified by the  .Po
 .BR -b ,  
 .BR -B ,  
 or  or
 .B -V  .Qq ~
   on systems that do not support long filenames
   .Pc ,
   or as specified by the
   .Fl b ,
   .Fl B ,
   or
   .Fl V
 switches.  switches.
 The extension used for making backup files may also be specified in the  The extension used for making backup files may also be specified in the
 .B SIMPLE_BACKUP_SUFFIX  .Ev SIMPLE_BACKUP_SUFFIX
 environment variable, which is overridden by the above switches.  environment variable, which is overridden by the above switches.
 .PP  .Pp
 If the backup file already exists,  If the backup file already exists,
 .B patch  .Nm
 creates a new backup file name by changing the first lowercase letter  creates a new backup file name by changing the first lowercase letter
 in the last component of the file's name into uppercase.  If there are  in the last component of the file's name into uppercase.
 no more lowercase letters in the name, it removes the first character  If there are no more lowercase letters in the name,
 from the name.  It repeats this process until it comes up with a  it removes the first character from the name.
   It repeats this process until it comes up with a
 backup file that does not already exist.  backup file that does not already exist.
 .PP  .Pp
 You may also specify where you want the output to go with a  You may also specify where you want the output to go with the
 .B -o  .Fl o
 switch; if that file already exists, it is backed up first.  switch; if that file already exists, it is backed up first.
 .PP  .Pp
 If  If
 .I patchfile  .Ar patchfile
 is omitted, or is a hyphen, the patch will be read from standard input.  is omitted, or is a hyphen, the patch will be read from standard input.
 .PP  .Pp
 Upon startup, patch will attempt to determine the type of the diff listing,  Upon startup,
   .Nm
   will attempt to determine the type of the diff listing,
 unless over-ruled by a  unless over-ruled by a
 .BR -c ,  .Fl c ,
 .BR -e ,  .Fl e ,
 .BR -n ,  .Fl n ,
 or  or
 .B -u  .Fl u
 switch.  switch.
 Context diffs (old-style, new-style, and unified) and  Context diffs (old-style, new-style, and unified) and
 normal diffs are applied by the  normal diffs are applied by the
 .I patch  .Nm
 program itself, while ed diffs are simply fed to the  program itself, while ed diffs are simply fed to the
 .I ed  .Xr ed 1
 editor via a pipe.  editor via a pipe.
 .PP  .Pp
 .I Patch  .Nm
 will try to skip any leading garbage, apply the diff,  will try to skip any leading garbage, apply the diff,
 and then skip any trailing garbage.  and then skip any trailing garbage.
 Thus you could feed an article or message containing a  Thus you could feed an article or message containing a
 diff listing to  diff listing to
 .IR patch ,  .Nm patch ,
 and it should work.  and it should work.
 If the entire diff is indented by a consistent amount,  If the entire diff is indented by a consistent amount,
 this will be taken into account.  this will be taken into account.
 .PP  .Pp
 With context diffs, and to a lesser extent with normal diffs,  With context diffs, and to a lesser extent with normal diffs,
 .I patch  .Nm
 can detect when the line numbers mentioned in the patch are incorrect,  can detect when the line numbers mentioned in the patch are incorrect,
 and will attempt to find the correct place to apply each hunk of the patch.  and will attempt to find the correct place to apply each hunk of the patch.
 As a first guess, it takes the line number mentioned for the hunk, plus or  As a first guess, it takes the line number mentioned for the hunk, plus or
 minus any offset used in applying the previous hunk.  minus any offset used in applying the previous hunk.
 If that is not the correct place,  If that is not the correct place,
 .I patch  .Nm
 will scan both forwards and backwards for a set of lines matching the context  will scan both forwards and backwards for a set of lines matching the context
 given in the hunk.  given in the hunk.
 First  First
 .I patch  .Nm
 looks for a place where all lines of the context match.  looks for a place where all lines of the context match.
 If no such place is found, and it's a context diff, and the maximum fuzz factor  If no such place is found, and it's a context diff, and the maximum fuzz factor
 is set to 1 or more, then another scan takes place ignoring the first and last  is set to 1 or more, then another scan takes place ignoring the first and last
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 If that fails, and the maximum fuzz factor is set to 2 or more,  If that fails, and the maximum fuzz factor is set to 2 or more,
 the first two and last two lines of context are ignored,  the first two and last two lines of context are ignored,
 and another scan is made.  and another scan is made.
 (The default maximum fuzz factor is 2.)  .Pq The default maximum fuzz factor is 2.
   .Pp
 If  If
 .I patch  .Nm
 cannot find a place to install that hunk of the patch, it will put the  cannot find a place to install that hunk of the patch, it will put the hunk
 hunk out to a reject file, which normally is the name of the output file  out to a reject file, which normally is the name of the output file plus
 plus \*(L".rej\*(R" (\*(L"#\*(R" on systems that do not support  .Qq .rej
 long filenames).  .Po
   or
   .Qq #
   on systems that do not support long filenames
   .Pc .
 (Note that the rejected hunk will come out in context diff form whether the  (Note that the rejected hunk will come out in context diff form whether the
 input patch was a context diff or a normal diff.  input patch was a context diff or a normal diff.
 If the input was a normal diff, many of the contexts will simply be null.)  If the input was a normal diff, many of the contexts will simply be null.)
 The line numbers on the hunks in the reject file may be different than  The line numbers on the hunks in the reject file may be different than
 in the patch file: they reflect the approximate location patch thinks the  in the patch file: they reflect the approximate location patch thinks the
 failed hunks belong in the new file rather than the old one.  failed hunks belong in the new file rather than the old one.
 .PP  .Pp
 As each hunk is completed, you will be told whether the hunk succeeded or  As each hunk is completed, you will be told whether the hunk succeeded or
 failed, and which line (in the new file)  failed, and which line (in the new file)
 .I patch  .Nm
 thought the hunk should go on.  thought the hunk should go on.
 If this is different from the line number specified in the diff you will  If this is different from the line number specified in the diff,
 be told the offset.  you will be told the offset.
 A single large offset MAY be an indication that a hunk was installed in the  A single large offset MAY be an indication that a hunk was installed in the
 wrong place.  wrong place.
 You will also be told if a fuzz factor was used to make the match, in which  You will also be told if a fuzz factor was used to make the match, in which
 case you should also be slightly suspicious.  case you should also be slightly suspicious.
 .PP  .Pp
 If no original file is specified on the command line,  If no original file is specified on the command line,
 .I patch  .Nm
 will try to figure out from the leading garbage what the name of the file  will try to figure out from the leading garbage what the name of the file
 to edit is.  to edit is.
 In the header of a context diff, the filename is found from lines beginning  In the header of a context diff, the filename is found from lines beginning
 with \*(L"***\*(R" or \*(L"---\*(R", with the shortest name of an existing  with
 file winning.  .Qq ***
 Only context diffs have lines like that, but if there is an \*(L"Index:\*(R"  or
   .Qq --- ,
   with the shortest name of an existing file winning.
   Only context diffs have lines like that, but if there is an
   .Qq Index:
 line in the leading garbage,  line in the leading garbage,
 .I patch  .Nm
 will try to use the filename from that line.  will try to use the filename from that line.
 The context diff header takes precedence over an Index line.  The context diff header takes precedence over an Index line.
 If no filename can be intuited from the leading garbage, you will be asked  If no filename can be intuited from the leading garbage, you will be asked
 for the name of the file to patch.  for the name of the file to patch.
 .PP  .Pp
 If the original file cannot be found or is read-only, but a suitable  If the original file cannot be found or is read-only, but a suitable
 SCCS or RCS file is handy,  SCCS or RCS file is handy,
 .I patch  .Nm
 will attempt to get or check out the file.  will attempt to get or check out the file.
 .PP  .Pp
 Additionally, if the leading garbage contains a \*(L"Prereq: \*(R" line,  Additionally, if the leading garbage contains a
 .I patch  .Qq Prereq:\ \&
   line,
   .Nm
 will take the first word from the prerequisites line (normally a version  will take the first word from the prerequisites line (normally a version
 number) and check the input file to see if that word can be found.  number) and check the input file to see if that word can be found.
 If not,  If not,
 .I patch  .Nm
 will ask for confirmation before proceeding.  will ask for confirmation before proceeding.
 .PP  .Pp
 The upshot of all this is that you should be able to say, while in a news  The upshot of all this is that you should be able to say, while in a news
 interface, the following:  interface, the following:
 .Sp  .Pp
         | patch -d /usr/src/local/blurfl  .Dl | patch -d /usr/src/local/blurfl
 .Sp  .Pp
 and patch a file in the blurfl directory directly from the article containing  and patch a file in the blurfl directory directly from the article containing
 the patch.  the patch.
 .PP  .Pp
 If the patch file contains more than one patch,  If the patch file contains more than one patch,
 .I patch  .Nm
 will try to apply each of them as if they came from separate patch files.  will try to apply each of them as if they came from separate patch files.
 This means, among other things, that it is assumed that the name of the file  This means, among other things, that it is assumed that the name of the file
 to patch must be determined for each diff listing,  to patch must be determined for each diff listing,
 and that the garbage before each diff listing will  and that the garbage before each diff listing will
 be examined for interesting things such as filenames and revision level, as  be examined for interesting things such as filenames and revision level, as
 mentioned previously.  mentioned previously.
 .PP  .Pp
 .I Patch  .Nm
 recognizes the following switches:  recognizes the following switches:
 .TP 5  .Bl -tag -width Ds
 .B \-b or \-\-suffix  .It Fl b , Fl Fl suffix
 causes the next argument to be interpreted as the backup extension, to be  Causes the next argument to be interpreted as the backup extension, to be
 used in place of \*(L".orig\*(R" or \*(L"~\*(R".  used in place of
 .TP 5  .Qq .orig
 .B \-B or \-\-prefix  or
 causes the next argument to be interpreted as a prefix to the backup file  .Qq ~ .
 name. If this argument is specified any argument from -b will be ignored.  .It Fl B , Fl Fl prefix
 .TP 5  Causes the next argument to be interpreted as a prefix to the backup file
 .B \-c or \-\-context  name.
 forces  If this argument is specified, any argument from
 .I patch  .Fl b
   will be ignored.
   .It Fl c , Fl Fl context
   Forces
   .Nm
 to interpret the patch file as a context diff.  to interpret the patch file as a context diff.
 .TP 5  .It Fl C , Fl Fl check
 .B \-C or \-\-check  Checks that the patch would apply cleanly, but does not modify anything.
 checks that the patch would apply cleanly, but does not modify anything.  .It Fl d , Fl Fl directory
 .TP 5  Causes
 .B \-d or \-\-directory  .Nm
 causes  to interpret the next argument as a directory, and
 .I patch  .Xr cd 1
 to interpret the next argument as a directory, and cd to it before doing  to it before doing anything else.
 anything else.  .It Fl D , Fl Fl ifdef
 .TP 5  Causes
 .B \-D or \-\-ifdef  .Nm
 causes  to use the
 .I patch  .Qq #ifdef...#endif
 to use the "#ifdef...#endif" construct to mark changes.  construct to mark changes.
 The argument following will be used as the differentiating symbol.  The argument following will be used as the differentiating symbol.
 Note that, unlike the C compiler, there must be a space between the  Note that, unlike the C compiler, there must be a space between the
 .B \-D  .Fl D
 and the argument.  and the argument.
 .TP 5  .It Fl e , Fl Fl ed
 .B \-e or \-\-ed  Forces
 forces  .Nm
 .I patch  to interpret the patch file as an
 to interpret the patch file as an ed script.  .Xr ed 1
 .TP 5  script.
 .B \-E or \-\-remove-empty-files  .It Fl E , Fl Fl remove-empty-files
 causes  Causes
 .I patch  .Nm
 to remove output files that are empty after the patches have been applied.  to remove output files that are empty after the patches have been applied.
 .TP 5  .It Fl f , Fl Fl force
 .B \-f or \-\-force  Forces
 forces  .Nm
 .I patch  
 to assume that the user knows exactly what he or she is doing, and to not  to assume that the user knows exactly what he or she is doing, and to not
 ask any questions.  It assumes the following: skip patches for which a  ask any questions.
 file to patch can't be found; patch files even though they have the  It assumes the following:
 wrong version for the ``Prereq:'' line in the patch; and assume that  skip patches for which a file to patch can't be found;
 patches are not reversed even if they look like they are.  patch files even though they have the wrong version for the
   .Qq Prereq:
   line in the patch;
   and assume that patches are not reversed even if they look like they are.
 This option does not suppress commentary; use  This option does not suppress commentary; use
 .B \-s  .Fl s
 for that.  for that.
 .TP 5  .It Fl t , Fl Fl batch
 .B \-t or \-\-batch  Similar to
 similar to  .Fl f ,
 .BR \-f ,  
 in that it suppresses questions, but makes some different assumptions:  in that it suppresses questions, but makes some different assumptions:
 skip patches for which a file to patch can't be found (the same as \fB\-f\fP);  skip patches for which a file to patch can't be found (the same as
 skip patches for which the file has the wrong version for the ``Prereq:'' line  .Fl f ) ;
 in the patch; and assume that patches are reversed if they look like  skip patches for which the file has the wrong version for the
 they are.  .Qq Prereq:
 .TP 5  line in the patch;
 .B \-F<number> or \-\-fuzz <number>  and assume that patches are reversed if they look like they are.
 sets the maximum fuzz factor.  .It Xo
   .Fl F Ns Aq Ar number ,
   .Fl Fl fuzz Aq Ar number
   .Xc
   Sets the maximum fuzz factor.
 This switch only applies to context diffs, and causes  This switch only applies to context diffs, and causes
 .I patch  .Nm
 to ignore up to that many lines in looking for places to install a hunk.  to ignore up to that many lines in looking for places to install a hunk.
 Note that a larger fuzz factor increases the odds of a faulty patch.  Note that a larger fuzz factor increases the odds of a faulty patch.
 The default fuzz factor is 2, and it may not be set to more than  The default fuzz factor is 2, and it may not be set to more than
 the number of lines of context in the context diff, ordinarily 3.  the number of lines of context in the context diff, ordinarily 3.
 .TP 5  .It Fl l , Fl Fl ignore-whitespace
 .B \-l or \-\-ignore-whitespace  Causes the pattern matching to be done loosely, in case the tabs and
 causes the pattern matching to be done loosely, in case the tabs and  
 spaces have been munged in your input file.  spaces have been munged in your input file.
 Any sequence of whitespace in the pattern line will match any sequence  Any sequence of whitespace in the pattern line will match any sequence
 in the input file.  in the input file.
 Normal characters must still match exactly.  Normal characters must still match exactly.
 Each line of the context must still match a line in the input file.  Each line of the context must still match a line in the input file.
 .TP 5  .It Fl n , Fl Fl normal
 .B \-n or \-\-normal  Forces
 forces  .Nm
 .I patch  
 to interpret the patch file as a normal diff.  to interpret the patch file as a normal diff.
 .TP 5  .It Fl N , Fl Fl forward
 .B \-N or \-\-forward  Causes
 causes  .Nm
 .I patch  
 to ignore patches that it thinks are reversed or already applied.  to ignore patches that it thinks are reversed or already applied.
 See also  See also
 .B \-R .  .Fl R .
 .TP 5  .It Fl o , Fl Fl output
 .B \-o or \-\-output  Causes the next argument to be interpreted as the output file name.
 causes the next argument to be interpreted as the output file name.  .It Xo
 .TP 5  .Fl p Ns Aq Ar number ,
 .B \-p<number> or \-\-strip <number>  .Fl Fl strip Aq Ar number
 sets the pathname strip count,  .Xc
 which controls how pathnames found in the patch file are treated, in case  Sets the pathname strip count,
 you keep your files in a different directory than the person who sent  which controls how pathnames found in the patch file are treated,
   in case you keep your files in a different directory than the person who sent
 out the patch.  out the patch.
 The strip count specifies how many slashes are to be stripped from  The strip count specifies how many slashes are to be stripped from
 the front of the pathname.  the front of the pathname.
 (Any intervening directory names also go away.)  (Any intervening directory names also go away.)
 For example, supposing the filename in the patch file was  For example, supposing the filename in the patch file was
 .sp  .Pa /u/howard/src/blurfl/blurfl.c :
         /u/howard/src/blurfl/blurfl.c  .Pp
 .sp  Setting
 setting  .Fl p
 .B \-p  
 or  or
 .B \-p0  .Fl p Ns Ar 0
 gives the entire pathname unmodified,  gives the entire pathname unmodified.
 .B \-p1  .Pp
   .Fl p Ns Ar 1
 gives  gives
 .sp  .Pp
         u/howard/src/blurfl/blurfl.c  .D1 Pa u/howard/src/blurfl/blurfl.c
 .sp  .Pp
 without the leading slash,  without the leading slash.
 .B \-p4  .Pp
   .Fl p Ns Ar 4
 gives  gives
 .sp  .Pp
         blurfl/blurfl.c  .D1 Pa blurfl/blurfl.c
 .sp  .Pp
 and not specifying  Not specifying
 .B \-p  .Fl p
 at all just gives you "blurfl.c", unless all of the directories in the  at all just gives you
 leading path (u/howard/src/blurfl) exist and that path is relative,  .Pa blurfl.c ,
   unless all of the directories in the leading path
   .Pq Pa u/howard/src/blurfl
   exist and that path is relative,
 in which case you get the entire pathname unmodified.  in which case you get the entire pathname unmodified.
 Whatever you end up with is looked for either in the current directory,  Whatever you end up with is looked for either in the current directory,
 or the directory specified by the  or the directory specified by the
 .B \-d  .Fl d
 switch.  switch.
 .TP 5  .It Fl r , Fl Fl reject-file
 .B \-r or \-\-reject-file  Causes the next argument to be interpreted as the reject file name.
 causes the next argument to be interpreted as the reject file name.  .It Fl R , Fl Fl reverse
 .TP 5  Tells
 .B \-R or \-\-reverse  .Nm
 tells  
 .I patch  
 that this patch was created with the old and new files swapped.  that this patch was created with the old and new files swapped.
 (Yes, I'm afraid that does happen occasionally, human nature being what it  (Yes, I'm afraid that does happen occasionally, human nature being what it
 is.)  is.)
 .I Patch  .Nm
 will attempt to swap each hunk around before applying it.  will attempt to swap each hunk around before applying it.
 Rejects will come out in the swapped format.  Rejects will come out in the swapped format.
 The  The
 .B \-R  .Fl R
 switch will not work with ed diff scripts because there is too little  switch will not work with ed diff scripts because there is too little
 information to reconstruct the reverse operation.  information to reconstruct the reverse operation.
 .Sp  .Pp
 If the first hunk of a patch fails,  If the first hunk of a patch fails,
 .I patch  .Nm
 will reverse the hunk to see if it can be applied that way.  will reverse the hunk to see if it can be applied that way.
 If it can, you will be asked if you want to have the  If it can, you will be asked if you want to have the
 .B \-R  .Fl R
 switch set.  switch set.
 If it can't, the patch will continue to be applied normally.  If it can't, the patch will continue to be applied normally.
 (Note: this method cannot detect a reversed patch if it is a normal diff  (Note: this method cannot detect a reversed patch if it is a normal diff
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 Luckily, most patches add or change lines rather than delete them, so most  Luckily, most patches add or change lines rather than delete them, so most
 reversed normal diffs will begin with a delete, which will fail, triggering  reversed normal diffs will begin with a delete, which will fail, triggering
 the heuristic.)  the heuristic.)
 .TP 5  .It Xo
 .B \-s or \-\-quiet or \-\-silent  .Fl s , Fl Fl quiet ,
 makes  .Fl Fl silent
 .I patch  .Xc
   Makes
   .Nm
 do its work silently, unless an error occurs.  do its work silently, unless an error occurs.
 .TP 5  .It Fl u , Fl Fl unified
 .B \-u or \-\-unified  Forces
 forces  .Nm
 .I patch  
 to interpret the patch file as a unified context diff (a unidiff).  to interpret the patch file as a unified context diff (a unidiff).
 .TP 5  .It Fl v , Fl Fl version
 .B \-v or \-\-version  Causes
 causes  .Nm
 .I patch  
 to print out its revision header and patch level.  to print out its revision header and patch level.
 .TP 5  .It Fl V , Fl Fl version-control
 .B \-V or \-\-version-control  Causes the next argument to be interpreted as a method for creating
 causes the next argument to be interpreted as a method for creating  backup file names.
 backup file names.  The type of backups made can also be given in the  The type of backups made can also be given in the
 .B VERSION_CONTROL  .Ev VERSION_CONTROL
 environment variable, which is overridden by this option.  environment variable, which is overridden by this option.
 The  The
 .B -B  .Fl B
 option overrides this option, causing the prefix to always be used for  option overrides this option, causing the prefix to always be used for
 making backup file names.  making backup file names.
 The value of the  The value of the
 .B VERSION_CONTROL  .Ev VERSION_CONTROL
 environment variable and the argument to the  environment variable and the argument to the
 .B -V  .Fl V
 option are like the GNU  option are like the GNU Emacs
 Emacs `version-control' variable; they also recognize synonyms that  .Dq version-control
 are more descriptive.  The valid values are (unique abbreviations are  variable; they also recognize synonyms that are more descriptive.
 accepted):  The valid values are (unique abbreviations are accepted):
 .RS  .Bl -tag -width Ds -offset indent
 .TP  .It t , numbered
 `t' or `numbered'  
 Always make numbered backups.  Always make numbered backups.
 .TP  .It nil , existing
 `nil' or `existing'  Make numbered backups of files that already have them,
 Make numbered backups of files that already  simple backups of the others.
 have them, simple backups of the others.  
 This is the default.  This is the default.
 .TP  .It never , simple
 `never' or `simple'  
 Always make simple backups.  Always make simple backups.
 .RE  .El
 .TP 5  .It Xo
 .B \-x<number> or \-\-debug <number>  .Fl x Ns Aq Ar number ,
 sets internal debugging flags, and is of interest only to  .Fl Fl debug Aq Ar number
 .I patch  .Xc
   Sets internal debugging flags, and is of interest only to
   .Nm
 patchers.  patchers.
 .SH AUTHOR  .El
 Larry Wall <lwall@netlabs.com>  .Sh NOTES FOR PATCH SENDERS
 .br  
 with many other contributors.  
 .SH ENVIRONMENT  
 .TP  
 .B TMPDIR  
 Directory to put temporary files in; default is /tmp.  
 .TP  
 .B SIMPLE_BACKUP_SUFFIX  
 Extension to use for backup file names instead of \*(L".orig\*(R" or  
 \*(L"~\*(R".  
 .TP  
 .B VERSION_CONTROL  
 Selects when numbered backup files are made.  
 .SH FILES  
 $TMPDIR/patch*  
 .SH SEE ALSO  
 diff(1)  
 .SH NOTES FOR PATCH SENDERS  
 There are several things you should bear in mind if you are going to  There are several things you should bear in mind if you are going to
 be sending out patches.  be sending out patches:
 First, you can save people a lot of grief by keeping a patchlevel.h file  .Pp
 which is patched to increment the patch level as the first diff in the  First, you can save people a lot of grief by keeping a
   .Pa patchlevel.h
   file which is patched to increment the patch level as the first diff in the
 patch file you send out.  patch file you send out.
 If you put a Prereq: line in with the patch, it won't let them apply  If you put a
   .Qq Prereq:
   line in with the patch, it won't let them apply
 patches out of order without some warning.  patches out of order without some warning.
   .Pp
 Second, make sure you've specified the filenames right, either in a  Second, make sure you've specified the filenames right, either in a
 context diff header, or with an Index: line.  context diff header, or with an
   .Qq Index:
   line.
 If you are patching something in a subdirectory, be sure to tell the patch  If you are patching something in a subdirectory, be sure to tell the patch
 user to specify a  user to specify a
 .B \-p  .Fl p
 switch as needed.  switch as needed.
   .Pp
 Third, you can create a file by sending out a diff that compares a  Third, you can create a file by sending out a diff that compares a
 null file to the file you want to create.  null file to the file you want to create.
 This will only work if the file you want to create doesn't exist already in  This will only work if the file you want to create doesn't exist already in
 the target directory.  the target directory.
   .Pp
 Fourth, take care not to send out reversed patches, since it makes people wonder  Fourth, take care not to send out reversed patches, since it makes people wonder
 whether they already applied the patch.  whether they already applied the patch.
   .Pp
 Fifth, while you may be able to get away with putting 582 diff listings into  Fifth, while you may be able to get away with putting 582 diff listings into
 one file, it is probably wiser to group related patches into separate files in  one file, it is probably wiser to group related patches into separate files in
 case something goes haywire.  case something goes haywire.
 .SH DIAGNOSTICS  .Sh ENVIRONMENT
   .Bl -tag -width "SIMPLE_BACKUP_SUFFIX" -compact
   .It Ev TMPDIR
   Directory to put temporary files in; default is
   .Pa /tmp .
   .It Ev SIMPLE_BACKUP_SUFFIX
   Extension to use for backup file names instead of
   .Qq .orig
   or
   .Qq ~ .
   .It Ev VERSION_CONTROL
   Selects when numbered backup files are made.
   .El
   .Sh FILES
   .Bl -tag -width Ds
   .It Pa $TMPDIR/patch*
   .El
   .Sh DIAGNOSTICS
 Too many to list here, but generally indicative that  Too many to list here, but generally indicative that
 .I patch  .Nm
 couldn't parse your patch file.  couldn't parse your patch file.
 .PP  .Pp
 The message \*(L"Hmm...\*(R" indicates that there is unprocessed text in  The message
 the patch file and that  .Qq Hmm...
 .I patch  indicates that there is unprocessed text in the patch file and that
   .Nm
 is attempting to intuit whether there is a patch in that text and, if so,  is attempting to intuit whether there is a patch in that text and, if so,
 what kind of patch it is.  what kind of patch it is.
 .PP  .Pp
 .I Patch  .Nm
 will exit with a non-zero status if any reject files were created.  will exit with a non-zero status if any reject files were created.
 When applying a set of patches in a loop it behooves you to check this  When applying a set of patches in a loop it behooves you to check this
 exit status so you don't apply a later patch to a partially patched file.  exit status so you don't apply a later patch to a partially patched file.
 .SH CAVEATS  .Sh SEE ALSO
 .I Patch  .Xr diff 1
   .Sh AUTHORS
   .An Larry Wall Aq lwall@netlabs.com
   with many other contributors.
   .Sh CAVEATS
   .Nm
 cannot tell if the line numbers are off in an ed script, and can only detect  cannot tell if the line numbers are off in an ed script, and can only detect
 bad line numbers in a normal diff when it finds a \*(L"change\*(R" or  bad line numbers in a normal diff when it finds a
 a \*(L"delete\*(R" command.  .Qq change
   or a
   .Qq delete
   command.
 A context diff using fuzz factor 3 may have the same problem.  A context diff using fuzz factor 3 may have the same problem.
 Until a suitable interactive interface is added, you should probably do  Until a suitable interactive interface is added, you should probably do
 a context diff in these cases to see if the changes made sense.  a context diff in these cases to see if the changes made sense.
 Of course, compiling without errors is a pretty good indication that the patch  Of course, compiling without errors is a pretty good indication that the patch
 worked, but not always.  worked, but not always.
 .PP  .Pp
 .I Patch  .Nm
 usually produces the correct results, even when it has to do a lot of  usually produces the correct results, even when it has to do a lot of
 guessing.  guessing.
 However, the results are guaranteed to be correct only when the patch is  However, the results are guaranteed to be correct only when the patch is
 applied to exactly the same version of the file that the patch was  applied to exactly the same version of the file that the patch was
 generated from.  generated from.
 .SH BUGS  .Sh BUGS
 Could be smarter about partial matches, excessively \&deviant offsets and  Could be smarter about partial matches, excessively deviant offsets and
 swapped code, but that would take an extra pass.  swapped code, but that would take an extra pass.
 .PP  .Pp
 Check patch mode (  Check patch mode
 .BR -C )  .Pq Fl C
 will fail if you try to check several patches in succession that build on  will fail if you try to check several patches in succession that build on
 each other.  The whole code of  each other.
 .I patch  The whole code of
   .Nm
 would have to be restructured to keep temporary files around so that it can  would have to be restructured to keep temporary files around so that it can
 handle this situation.  handle this situation.
 .PP  .Pp
 If code has been duplicated (for instance with #ifdef OLDCODE ... #else ...  If code has been duplicated (for instance with #ifdef OLDCODE ... #else ...
 #endif),  #endif),
 .I patch  .Nm
 is incapable of patching both versions, and, if it works at all, will likely  is incapable of patching both versions, and, if it works at all, will likely
 patch the wrong one, and tell you that it succeeded to boot.  patch the wrong one, and tell you that it succeeded to boot.
 .PP  .Pp
 If you apply a patch you've already applied,  If you apply a patch you've already applied,
 .I patch  .Nm
 will think it is a reversed patch, and offer to un-apply the patch.  will think it is a reversed patch, and offer to un-apply the patch.
 This could be construed as a feature.  This could be construed as a feature.
 .rn }` ''  
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  Added in v.1.9