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authorjoerg <joerg@NetBSD.org>2008-09-19 18:33:34 +0000
committerjoerg <joerg@NetBSD.org>2008-09-19 18:33:34 +0000
commitd5b2c9a8256bb738e99f71510f32d4ab70f76f03 (patch)
treeade297b9e3ea4e09610f0640b0687a97022e80ec /usr.bin/patch/patch.1
parent97e276be341799ee7ff55d4c7625d953c4c93266 (diff)
Update patch to the version used by DragonFly and derived from OpenBSD.
Major changes are: - better detection of double applied patches - rejects remain unified diffs for unified patches - far less limitations, e.g. patch lines may be arbitrary long This addresses PR standards/11220 by changing patch -b behavior to be POSIX compliant. Old behavior can be obtained using --suffix, which works since NetBSD 1.4. pkgsrc has been adjusted accordingly.
Diffstat (limited to 'usr.bin/patch/patch.1')
-rw-r--r--usr.bin/patch/patch.11022
1 files changed, 592 insertions, 430 deletions
diff --git a/usr.bin/patch/patch.1 b/usr.bin/patch/patch.1
index aa935b67bc7..b07efdcd7b3 100644
--- a/usr.bin/patch/patch.1
+++ b/usr.bin/patch/patch.1
@@ -1,368 +1,266 @@
-.\" $NetBSD: patch.1,v 1.12 2005/03/25 23:55:02 wiz Exp $ -*- nroff -*-
-.rn '' }`
-.de Sh
-.br
-.ne 5
-.PP
-\fB\\$1\fR
-.PP
-..
-.de Sp
-.if t .sp .5v
-.if n .sp
-..
-'\"
-'\" Set up \*(-- to give an unbreakable dash;
-'\" string Tr holds user defined translation string.
-'\" Bell System Logo is used as a dummy character.
-'\"
-'\" Shut up a groff -ww warning.
-.if \n(.g .if !dTr .ds Tr
-.ie n \{\
-.tr \(*W-\*(Tr
-.ds -- \(*W-
-.if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
-.if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch
-.ds L" ""
-.ds R" ""
-.ds L' '
-.ds R' '
-'br \}
-.el \{\
-.ds -- \(em\|
-.tr \*(Tr
-.ds L" ``
-.ds R" ''
-.ds L' `
-.ds R' '
-'br\}
-.TH PATCH 1
-.SH NAME
-patch - apply a diff file to an original
-.SH SYNOPSIS
-.B patch
-[options] [origfile [patchfile]] [+ [options] [origfile]]...
-.sp
-but usually just
-.sp
-.B patch
-\*[Lt]patchfile
-.SH DESCRIPTION
-.I Patch
+.\" $OpenBSD: patch.1,v 1.22 2008/06/06 20:44:00 jmc Exp $
+.\" $DragonFly: src/usr.bin/patch/patch.1,v 1.10 2008/08/18 19:15:55 joerg Exp $
+.\" $NetBSD: patch.1,v 1.13 2008/09/19 18:33:34 joerg Exp $
+.\" Copyright 1986, Larry Wall
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following condition
+.\" is met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\" notice, this condition and the following disclaimer.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.Dd August 18, 2008
+.Dt PATCH 1
+.Os
+.Sh NAME
+.Nm patch
+.Nd apply a diff file to an original
+.Sh SYNOPSIS
+.Nm
+.Bk -words
+.Op Fl bCcEeflNnRstuv
+.Op Fl B Ar backup-prefix
+.Op Fl D Ar symbol
+.Op Fl d Ar directory
+.Op Fl F Ar max-fuzz
+.Op Fl i Ar patchfile
+.Op Fl o Ar out-file
+.Op Fl p Ar strip-count
+.Op Fl r Ar rej-name
+.Op Fl V Cm t | nil | never
+.Op Fl x Ar number
+.Op Fl z Ar backup-ext
+.Op Fl Fl posix
+.Op Ar origfile Op Ar patchfile
+.Ek
+.Nm
+.Pf \*(Lt Ar patchfile
+.Sh DESCRIPTION
+.Nm
will take a patch file containing any of the four forms of difference
listing produced by the
-.I diff
-program and apply those differences to an original file, producing a patched
-version.
-By default, the patched version is put in place of the original, with
-the original file backed up to the same name with the
-extension \*(L".orig\*(R" (\*(L"~\*(R" on systems that do not
-support long filenames), or as specified by the
-.BR -b ,
-.BR -B ,
-or
-.B -V
-switches.
-The extension used for making backup files may also be specified in the
-.B SIMPLE_BACKUP_SUFFIX
-environment variable, which is overridden by above switches.
-.PP
-If the backup file already exists,
-.B patch
-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
-no more lowercase letters in the name, 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.
-.PP
-You may also specify where you want the output to go with a
-.B -o
-switch; if that file already exists, it is backed up first.
-.PP
+.Xr diff 1
+program and apply those differences to an original file,
+producing a patched version.
If
-no
-.I patchfile
-argument is specified using the
-.BR -i
-option, and the
-.I patchfile
-argument is omitted, or is a hyphen, the patch will be read from standard input.
-.PP
-Upon startup, patch will attempt to determine the type of the diff listing,
-unless over-ruled by a
-.BR -c ,
-.BR -e ,
-.BR -n ,
+.Ar patchfile
+is omitted, or is a hyphen, the patch will be read from the standard input.
+.Pp
+.Nm
+will attempt to determine the type of the diff listing, unless over-ruled by a
+.Fl c ,
+.Fl e ,
+.Fl n ,
or
-.B -u
-switch.
+.Fl u
+option.
Context diffs (old-style, new-style, and unified) and
-normal diffs are applied by the
-.I patch
-program itself, while ed diffs are simply fed to the
-.I ed
+normal diffs are applied directly by the
+.Nm
+program itself, whereas ed diffs are simply fed to the
+.Xr ed 1
editor via a pipe.
-.PP
-.I Patch
-will try to skip any leading garbage, apply the diff,
-and then skip any trailing garbage.
-Thus you could feed an article or message containing a
-diff listing to
-.IR patch ,
-and it should work.
-If the entire diff is indented by a consistent amount,
-this will be taken into account.
-.PP
-With context diffs, and to a lesser extent with normal diffs,
-.I patch
-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.
-As a first guess, it takes the line number mentioned for the hunk, plus or
-minus any offset used in applying the previous hunk.
-If that is not the correct place,
-.I patch
-will scan both forwards and backwards for a set of lines matching the context
-given in the hunk.
-First
-.I patch
-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
-is set to 1 or more, then another scan takes place ignoring the first and last
-line of context.
-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,
-and another scan is made.
-(The default maximum fuzz factor is 2.)
-If
-.I patch
-cannot find a place to install that hunk of the patch, it will put the
-hunk out to a reject file, which normally is the name of the output file
-plus \*(L".rej\*(R" (\*(L"#\*(R" on systems that do not support
-long filenames).
-(Note that the rejected hunk will come out in context diff form whether the
-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.)
-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
-failed hunks belong in the new file rather than the old one.
-.PP
-As each hunk is completed, you will be told whether the hunk succeeded or
-failed, and which line (in the new file)
-.I patch
-thought the hunk should go on.
-If this is different from the line number specified in the diff you will
-be told the offset.
-A single large offset MAY be an indication that a hunk was installed in the
-wrong place.
-You will also be told if a fuzz factor was used to make the match, in which
-case you should also be slightly suspicious.
-.PP
-If no original file is specified on the command line,
-.I patch
-will try to figure out from the leading garbage what the name of the file
-to edit is.
-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
-file winning.
-Only context diffs have lines like that, but if there is an \*(L"Index:\*(R"
-line in the leading garbage,
-.I patch
-will try to use the filename from that 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
-for the name of the file to patch.
-.PP
-If the original file cannot be found or is read-only, but a suitable
-SCCS or RCS file is handy,
-.I patch
-will attempt to get or check out the file.
-.PP
-Additionally, if the leading garbage contains a \*(L"Prereq: \*(R" line,
-.I patch
-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.
-If not,
-.I patch
-will ask for confirmation before proceeding.
-.PP
-The upshot of all this is that you should be able to say, while in a news
-interface, the following:
-.Sp
- | patch -d /usr/src/local/blurfl
-.Sp
-and patch a file in the blurfl directory directly from the article containing
-the patch.
-.PP
-If the patch file contains more than one patch,
-.I patch
+.Pp
+If the
+.Ar patchfile
+contains more than one patch,
+.Nm
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
-to patch must be determined for each diff listing,
-and that the garbage before each diff listing will
-be examined for interesting things such as filenames and revision level, as
-mentioned previously.
-You can give switches (and another original file name) for the second and
-subsequent patches by separating the corresponding argument lists
-by a \*(L'+\*(R'.
-(The argument list for a second or subsequent patch may not specify a new
-patch file, however.)
-.PP
-.I Patch
-recognizes the following switches:
-.TP 5
-.B \-B or \-\-prefix
-causes the next argument to be interpreted as a prefix to the backup file
+to patch must be determined for each diff listing, and that the garbage before
+each diff listing will be examined for interesting things such as file names
+and revision level (see the section on
+.Sx Filename Determination
+below).
+.Pp
+The options are as follows:
+.Bl -tag -width Ds
+.It Xo
+.Fl B Ar backup-prefix ,
+.Fl Fl prefix Ar backup-prefix
+.Xc
+Causes the next argument to be interpreted as a prefix to the backup file
name.
-If this argument is specified any argument from -b will be ignored.
-.TP 5
-.B \-b or \-\-suffix
-causes the next argument to be interpreted as the backup extension, to be
-used in place of \*(L".orig\*(R" or \*(L"~\*(R".
-.TP 5
-.B \-C or \-\-dry\-run
-causes
-.I patch
-to report what would be done, but not to actually modify any files
-or create any rejects.
-.TP 5
-.B \-c or \-\-context
-forces
-.I patch
+If this argument is specified, any argument to
+.Fl z
+will be ignored.
+.It Fl b , Fl Fl backup
+Save a backup copy of the file before it is modified.
+By default the original file is saved with a backup extension of
+.Qq .orig
+unless the file already has a numbered backup, in which case a numbered
+backup is made.
+This is equivalent to specifying
+.Qo Fl V Cm existing Qc .
+This option is currently the default, unless
+.Fl -posix
+is specified.
+.It Fl C , Fl Fl check
+Checks that the patch would apply cleanly, but does not modify anything.
+.It Fl c , Fl Fl context
+Forces
+.Nm
to interpret the patch file as a context diff.
-.TP 5
-.B \-D or \-\-ifdef
-causes
-.I patch
-to use the "#ifdef...#endif" construct to mark changes.
+.It Xo
+.Fl D Ar symbol ,
+.Fl Fl ifdef Ar symbol
+.Xc
+Causes
+.Nm
+to use the
+.Qq #ifdef...#endif
+construct to mark changes.
The argument following will be used as the differentiating symbol.
Note that, unlike the C compiler, there must be a space between the
-.B \-D
+.Fl D
and the argument.
-.TP 5
-.B \-d or \-\-directory
-causes
-.I patch
-to interpret the next argument as a directory, and cd to it before doing
-anything else.
-.TP 5
-.B \-E or \-\-remove-empty-files
-causes
-.I patch
+.It Xo
+.Fl d Ar directory ,
+.Fl Fl directory Ar directory
+.Xc
+Causes
+.Nm
+to interpret the next argument as a directory,
+and change the working directory to it before doing anything else.
+.It Fl E , Fl Fl remove-empty-files
+Causes
+.Nm
to remove output files that are empty after the patches have been applied.
-.TP 5
-.B \-e or \-\-ed
-forces
-.I patch
-to interpret the patch file as an ed script.
-.TP 5
-.B \-F\*[Lt]number\*[Gt] or \-\-fuzz \*[Lt]number\*[Gt]
-sets the maximum fuzz factor.
-This switch only applies to context diffs, and causes
-.I patch
+This option is useful when applying patches that create or remove files.
+.It Fl e , Fl Fl ed
+Forces
+.Nm
+to interpret the patch file as an
+.Xr ed 1
+script.
+.It Xo
+.Fl F Ar max-fuzz ,
+.Fl Fl fuzz Ar max-fuzz
+.Xc
+Sets the maximum fuzz factor.
+This option only applies to context diffs, and causes
+.Nm
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.
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.
-.TP 5
-.B \-f or \-\-force
-forces
-.I patch
+.It Fl f , Fl Fl force
+Forces
+.Nm
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
-file to patch can't be found; patch files even though they have the
-wrong version for the ``Prereq:'' line in the patch; and assume that
-patches are not reversed even if they look like they are.
+It assumes the following:
+skip patches for which a file to patch can't be found;
+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
-.B \-s
+.Fl s
for that.
-.TP 5
-.B \-i \*[Lt]patchfile\*[Gt] or \-\-patchfile \*[Lt]patchfile\*[Gt]
-Read the patch to be applied from the specified file.
-.TP 5
-.B \-l or \-\-ignore-whitespace
-causes the pattern matching to be done loosely, in case the tabs and
+.It Xo
+.Fl i Ar patchfile ,
+.Fl Fl input Ar patchfile
+.Xc
+Causes the next argument to be interpreted as the input file name
+(i.e. a patchfile).
+This option may be specified multiple times.
+.It Fl l , Fl Fl ignore-whitespace
+Causes the pattern matching to be done loosely, in case the tabs and
spaces have been munged in your input file.
Any sequence of whitespace in the pattern line will match any sequence
in the input file.
Normal characters must still match exactly.
Each line of the context must still match a line in the input file.
-.TP 5
-.B \-N or \-\-forward
-causes
-.I patch
+.It Fl N , Fl Fl forward
+Causes
+.Nm
to ignore patches that it thinks are reversed or already applied.
See also
-.B \-R .
-.TP 5
-.B \-n or \-\-normal
-forces
-.I patch
+.Fl R .
+.It Fl n , Fl Fl normal
+Forces
+.Nm
to interpret the patch file as a normal diff.
-.TP 5
-.B \-o or \-\-output
-causes the next argument to be interpreted as the output file name.
-.TP 5
-.B \-p\*[Lt]number\*[Gt] or \-\-strip \*[Lt]number\*[Gt]
-sets the pathname strip count,
-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
+.It Xo
+.Fl o Ar out-file ,
+.Fl Fl output Ar out-file
+.Xc
+Causes the next argument to be interpreted as the output file name.
+.It Xo
+.Fl p Ar strip-count ,
+.Fl Fl strip Ar strip-count
+.Xc
+Sets the pathname strip count,
+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.
The strip count specifies how many slashes are to be stripped from
the front of the pathname.
(Any intervening directory names also go away.)
-For example, supposing the filename in the patch file was
-.sp
- /u/howard/src/blurfl/blurfl.c
-.sp
-setting
-.B \-p
-or
-.B \-p0
-gives the entire pathname unmodified,
-.B \-p1
+For example, supposing the file name in the patch file was
+.Pa /u/howard/src/blurfl/blurfl.c :
+.Pp
+Setting
+.Fl p Ns Ar 0
+gives the entire pathname unmodified.
+.Pp
+.Fl p Ns Ar 1
gives
-.sp
- u/howard/src/blurfl/blurfl.c
-.sp
-without the leading slash,
-.B \-p4
+.Pp
+.D1 Pa u/howard/src/blurfl/blurfl.c
+.Pp
+without the leading slash.
+.Pp
+.Fl p Ns Ar 4
gives
-.sp
- blurfl/blurfl.c
-.sp
-and not specifying
-.B \-p
-at all just gives you "blurfl.c", unless all of the directories in the
-leading path (u/howard/src/blurfl) exist and that path is relative,
+.Pp
+.D1 Pa blurfl/blurfl.c
+.Pp
+Not specifying
+.Fl p
+at all just gives you
+.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.
Whatever you end up with is looked for either in the current directory,
or the directory specified by the
-.B \-d
-switch.
-.TP 5
-.B \-R or \-\-reverse
-tells
-.I patch
+.Fl d
+option.
+.It Fl R , Fl Fl reverse
+Tells
+.Nm
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
is.)
-.I Patch
+.Nm
will attempt to swap each hunk around before applying it.
Rejects will come out in the swapped format.
The
-.B \-R
-switch will not work with ed diff scripts because there is too little
+.Fl R
+option will not work with ed diff scripts because there is too little
information to reconstruct the reverse operation.
-.Sp
+.Pp
If the first hunk of a patch fails,
-.I patch
+.Nm
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
-.B \-R
-switch set.
+.Fl R
+option set.
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
and if the first command is an append (i.e. it should have been a delete)
@@ -371,168 +269,432 @@ anywhere.
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
the heuristic.)
-.TP 5
-.B \-r or \-\-reject-file
-causes the next argument to be interpreted as the reject file name.
-.TP 5
-.B \-S or \-\-skip
-causes
-.I patch
-to ignore this patch from the patch file, but continue on looking
-for the next patch in the file.
-Thus
-.sp
- patch -S + -S + \*[Lt]patchfile
-.sp
-will ignore the first and second of three patches.
-.TP 5
-.B \-s or \-\-quiet or \-\-silent
-makes
-.I patch
+.It Xo
+.Fl r Ar rej-name ,
+.Fl Fl reject-file Ar rej-name
+.Xc
+Causes the next argument to be interpreted as the reject file name.
+.It Xo
+.Fl s , Fl Fl quiet ,
+.Fl Fl silent
+.Xc
+Makes
+.Nm
do its work silently, unless an error occurs.
-.TP 5
-.B \-t or \-\-batch
-similar to
-.BR \-f ,
+.It Fl t , Fl Fl batch
+Similar to
+.Fl f ,
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 the file has the wrong version for the ``Prereq:'' line
-in the patch; and assume that patches are reversed if they look like
-they are.
-.TP 5
-.B \-u or \-\-unified
-forces
-.I patch
+skip patches for which a file to patch can't be found (the same as
+.Fl f ) ;
+skip patches for which the file has the wrong version for the
+.Qq Prereq:
+line in the patch;
+and assume that patches are reversed if they look like they are.
+.It Fl u , Fl Fl unified
+Forces
+.Nm
to interpret the patch file as a unified context diff (a unidiff).
-.TP 5
-.B \-V or \-\-version-control
-causes the next argument to be interpreted as a method for creating
+.It Xo
+.Fl V Cm t | nil | never ,
+.Fl Fl version-control Cm t | nil | never
+.Xc
+Causes the next argument to be interpreted as a method for creating
backup file names.
The type of backups made can also be given in the
-.B VERSION_CONTROL
-environment variable, which is overridden by this option.
+.Ev PATCH_VERSION_CONTROL
+or
+.Ev VERSION_CONTROL
+environment variables, which are overridden by this option.
The
-.B -B
+.Fl B
option overrides this option, causing the prefix to always be used for
making backup file names.
-The value of the
-.B VERSION_CONTROL
-environment variable and the argument to the
-.B -V
-option are like the GNU
-Emacs `version-control' variable; they also recognize synonyms that
-are more descriptive.
-The valid values are (unique abbreviations are
-accepted):
-.RS
-.TP
-`t' or `numbered'
+The values of the
+.Ev PATCH_VERSION_CONTROL
+and
+.Ev VERSION_CONTROL
+environment variables and the argument to the
+.Fl V
+option are like the GNU Emacs
+.Dq version-control
+variable; they also recognize synonyms that are more descriptive.
+The valid values are (unique abbreviations are accepted):
+.Bl -tag -width Ds -offset indent
+.It Cm t , numbered
Always make numbered backups.
-.TP
-`nil' or `existing'
-Make numbered backups of files that already
-have them, simple backups of the others.
-This is the default.
-.TP
-`never' or `simple'
+.It Cm nil , existing
+Make numbered backups of files that already have them,
+simple backups of the others.
+.It Cm never , simple
Always make simple backups.
-.RE
-.TP 5
-.B \-v or \-\-version
-causes
-.I patch
+.El
+.It Fl v , Fl Fl version
+Causes
+.Nm
to print out its revision header and patch level.
-.TP 5
-.B \-x\*[Lt]number\*[Gt] or \-\-debug \*[Lt]number\*[Gt]
-sets internal debugging flags, and is of interest only to
-.I patch
+.It Xo
+.Fl x Ar number ,
+.Fl Fl debug Ar number
+.Xc
+Sets internal debugging flags, and is of interest only to
+.Nm
patchers.
-.SH AUTHOR
-Larry Wall \*[Lt]lwall@netlabs.com\*[Gt]
-.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
+.It Xo
+.Fl z Ar backup-ext ,
+.Fl Fl suffix Ar backup-ext
+.Xc
+Causes the next argument to be interpreted as the backup extension, to be
+used in place of
+.Qq .orig .
+.It Fl Fl posix
+Enables strict
+.St -p1003.1-2004
+conformance, specifically:
+.Bl -enum
+.It
+Backup files are not created unless the
+.Fl b
+option is specified.
+.It
+If unspecified, the file name used is the first of the old, new and
+index files that exists.
+.El
+.El
+.Ss Patch Application
+.Nm
+will try to skip any leading garbage, apply the diff,
+and then skip any trailing garbage.
+Thus you could feed an article or message containing a
+diff listing to
+.Nm ,
+and it should work.
+If the entire diff is indented by a consistent amount,
+this will be taken into account.
+.Pp
+With context diffs, and to a lesser extent with normal diffs,
+.Nm
+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.
+As a first guess, it takes the line number mentioned for the hunk, plus or
+minus any offset used in applying the previous hunk.
+If that is not the correct place,
+.Nm
+will scan both forwards and backwards for a set of lines matching the context
+given in the hunk.
+First
+.Nm
+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
+is set to 1 or more, then another scan takes place ignoring the first and last
+line of context.
+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,
+and another scan is made.
+.Pq The default maximum fuzz factor is 2.
+.Pp
+If
+.Nm
+cannot find a place to install that hunk of the patch, it will put the hunk
+out to a reject file, which normally is the name of the output file plus
+.Qq .rej .
+(Note that the rejected hunk will come out in context diff form whether the
+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.)
+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
+failed hunks belong in the new file rather than the old one.
+.Pp
+As each hunk is completed, you will be told whether the hunk succeeded or
+failed, and which line (in the new file)
+.Nm
+thought the hunk should go on.
+If this is different from the line number specified in the diff,
+you will be told the offset.
+A single large offset MAY be an indication that a hunk was installed in the
+wrong place.
+You will also be told if a fuzz factor was used to make the match, in which
+case you should also be slightly suspicious.
+.Ss Filename Determination
+If no original file is specified on the command line,
+.Nm
+will try to figure out from the leading garbage what the name of the file
+to edit is.
+When checking a prospective file name, pathname components are stripped
+as specified by the
+.Fl p
+option and the file's existence and writability are checked relative
+to the current working directory (or the directory specified by the
+.Fl d
+option).
+.Pp
+If the diff is a context or unified diff,
+.Nm
+is able to determine the old and new file names from the diff header.
+For context diffs, the
+.Dq old
+file is specified in the line beginning with
+.Qq ***
+and the
+.Dq new
+file is specified in the line beginning with
+.Qq --- .
+For a unified diff, the
+.Dq old
+file is specified in the line beginning with
+.Qq ---
+and the
+.Dq new
+file is specified in the line beginning with
+.Qq +++ .
+If there is an
+.Qq Index:
+line in the leading garbage (regardless of the diff type),
+.Nm
+will use the file name from that line as the
+.Dq index
+file.
+.Pp
+.Nm
+will choose the file name by performing the following steps, with the first
+match used:
+.Bl -enum
+.It
+If
+.Nm
+is operating in strict
+.St -p1003.1-2004
+mode, the first of the
+.Dq old ,
+.Dq new
+and
+.Dq index
+file names that exist is used.
+Otherwise,
+.Nm
+will examine either the
+.Dq old
+and
+.Dq new
+file names or, for a non-context diff, the
+.Dq index
+file name, and choose the file name with the fewest path components,
+the shortest basename, and the shortest total file name length (in that order).
+.It
+If no file exists,
+.Nm
+checks for the existence of the files in an SCCS or RCS directory
+(using the appropriate prefix or suffix) using the criteria specified
+above.
+If found,
+.Nm
+will attempt to get or check out the file.
+.It
+If no suitable file was found to patch, the patch file is a context or
+unified diff, and the old file was zero length, the new file name is
+created and used.
+.It
+If the file name still cannot be determined,
+.Nm
+will prompt the user for the file name to use.
+.El
+.Pp
+Additionally, if the leading garbage contains a
+.Qq Prereq:\ \&
+line,
+.Nm
+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.
+If not,
+.Nm
+will ask for confirmation before proceeding.
+.Pp
+The upshot of all this is that you should be able to say, while in a news
+interface, the following:
+.Pp
+.Dl | patch -d /usr/src/local/blurfl
+.Pp
+and patch a file in the blurfl directory directly from the article containing
+the patch.
+.Ss Backup Files
+By default, the patched version is put in place of the original, with
+the original file backed up to the same name with the extension
+.Qq .orig ,
+or as specified by the
+.Fl B ,
+.Fl V ,
+or
+.Fl z
+options.
+The extension used for making backup files may also be specified in the
+.Ev SIMPLE_BACKUP_SUFFIX
+environment variable, which is overridden by the options above.
+.Pp
+If the backup file is a symbolic or hard link to the original file,
+.Nm
+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 no more lowercase letters in the name,
+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 or is not linked to the original file.
+.Pp
+You may also specify where you want the output to go with the
+.Fl o
+option; if that file already exists, it is backed up first.
+.Ss Notes For Patch Senders
There are several things you should bear in mind if you are going to
-be sending out patches.
-First, you can save people a lot of grief by keeping a patchlevel.h file
-which is patched to increment the patch level as the first diff in the
+be sending out patches:
+.Pp
+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.
-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.
-Second, make sure you've specified the filenames right, either in a
-context diff header, or with an Index: line.
+.Pp
+Second, make sure you've specified the file names right, either in a
+context diff header, or with an
+.Qq Index:
+line.
If you are patching something in a subdirectory, be sure to tell the patch
user to specify a
-.B \-p
-switch as needed.
+.Fl p
+option as needed.
+.Pp
Third, you can create a file by sending out a diff that compares a
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
the target directory.
+.Pp
Fourth, take care not to send out reversed patches, since it makes people wonder
whether they already applied the patch.
+.Pp
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
case something goes haywire.
-.SH DIAGNOSTICS
+.Sh ENVIRONMENT
+.Bl -tag -width "PATCH_VERSION_CONTROL" -compact
+.It Ev POSIXLY_CORRECT
+When set,
+.Nm
+behaves as if the
+.Fl Fl posix
+option has been specified.
+.It Ev SIMPLE_BACKUP_SUFFIX
+Extension to use for backup file names instead of
+.Qq .orig .
+.It Ev TMPDIR
+Directory to put temporary files in; default is
+.Pa /tmp .
+.It Ev PATCH_VERSION_CONTROL
+Selects when numbered backup files are made.
+.It Ev VERSION_CONTROL
+Same as
+.Ev PATCH_VERSION_CONTROL .
+.El
+.Sh FILES
+.Bl -tag -width "$TMPDIR/patch*" -compact
+.It Pa $TMPDIR/patch*
+.Nm
+temporary files
+.It Pa /dev/tty
+used to read input when
+.Nm
+prompts the user
+.El
+.Sh DIAGNOSTICS
Too many to list here, but generally indicative that
-.I patch
+.Nm
couldn't parse your patch file.
-.PP
-The message \*(L"Hmm...\*(R" indicates that there is unprocessed text in
-the patch file and that
-.I patch
+.Pp
+The message
+.Qq Hmm...
+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,
what kind of patch it is.
-.PP
-.I Patch
-will exit with a non-zero status if any reject files were created.
+.Pp
+The
+.Nm
+utility exits with one of the following values:
+.Pp
+.Bl -tag -width Ds -compact -offset indent
+.It \&0
+Successful completion.
+.It \&1
+One or more lines were written to a reject file.
+.It \*[Gt]\&1
+An error occurred.
+.El
+.Pp
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.
-.SH CAVEATS
-.I Patch
+.Sh SEE ALSO
+.Xr diff 1
+.Sh STANDARDS
+The
+.Nm
+utility is compliant with the
+.St -p1003.1-2004
+specification
+(except as detailed above for the
+.Fl -posix
+option),
+though the presence of
+.Nm
+itself is optional.
+.Pp
+The flags
+.Op Fl CEfstuvBFVxz
+and
+.Op Fl -posix
+are extensions to that specification.
+.Sh AUTHORS
+.An Larry Wall
+with many other contributors.
+.Sh CAVEATS
+.Nm
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
-a \*(L"delete\*(R" command.
+bad line numbers in a normal diff when it finds a
+.Qq change
+or a
+.Qq delete
+command.
A context diff using fuzz factor 3 may have the same problem.
Until a suitable interactive interface is added, you should probably do
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
worked, but not always.
-.PP
-.I Patch
+.Pp
+.Nm
usually produces the correct results, even when it has to do a lot of
guessing.
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
generated from.
-.SH BUGS
-Could be smarter about partial matches, excessively \&deviant offsets and
+.Sh BUGS
+Could be smarter about partial matches, excessively deviant offsets and
swapped code, but that would take an extra pass.
-.PP
+.Pp
+Check patch mode
+.Pq Fl C
+will fail if you try to check several patches in succession that build on
+each other.
+The entire
+.Nm
+code would have to be restructured to keep temporary files around so that it
+can handle this situation.
+.Pp
If code has been duplicated (for instance with #ifdef OLDCODE ... #else ...
#endif),
-.I patch
+.Nm
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.
-.PP
+.Pp
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.
This could be construed as a feature.
-.rn }` ''