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分类： LINUX
2012-02-19 16:24:36
PATCH(1) PATCH(1)
NAME
patch - apply a diff file to an original
SYNOPSIS
patch [options] [originalfile [patchfile]]
but usually just
patch -pnum
DESCRIPTION
patch takes a patch file patchfile containing a difference listing produced by the diff program and applies
those differences to one or more original files, producing patched versions. Normally the patched versions
are put in place of the originals. Backups can be made; see the -b or --backup option. The names of the
files to be patched are usually taken from the patch file, but if there's just one file to be patched it
can specified on the command line as originalfile.
Patch接收输入文件patchfile,将这个输入文件的差异应用到一个或多个原始文件，从而生成一个补丁版本，同时还可以生成备份文件。
Upon startup, patch attempts to determine the type of the diff listing, unless overruled by a -c (--con-
text), -e (--ed), -n (--normal), or -u (--unified) option. Context diffs (old-style, new-style, and uni-
fied) and normal diffs are applied by the patch program itself, while ed diffs are simply fed to the ed(1)
editor via a pipe.
patch tries 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 patch, and it should work. If the entire
diff is indented by a consistent amount, or if a context diff contains lines ending in CRLF or is encapsu-
lated one or more times by prepending "- " to lines starting with "-" as specified by Internet RFC 934,
this is taken into account.
With context diffs, and to a lesser extent with normal diffs, patch can detect when the line numbers mentioned in the patch are incorrect, and attempts to find the correct place to apply each hunk of the patch.
对于上下文diff, 和轻度的标准diff来说，当行号不匹配时，patch会检测并尝试查找每个补丁块对应的正确的位置。
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, patch scans both forwards and backwards for a set of lines matching the context given in the hunk. First 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 patch cannot find a place to install that hunk of the patch, it puts the hunk out to a reject file, which normally is the name of the output file plus a .rej suffix, or # if .rej would generate a file name that is too long (if even appending the single character # makes the file name too long, then # replaces the file name's last character). (The rejected hunk comes out in ordinary context diff form regardless of the input patch's form. If the input was a normal diff, many of the contexts are simply 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.
Patch首先对当前补丁块的行号，加上或减去当前块对于前一个块的偏移量。
如果位置不匹配，patch会向前或身后扫描匹配当前块上下文的行集合。
首先，patch会查找匹配上下文所有行的位置。如果没有找到这样的位置，并且是一个上下文diff时，它的最大模糊因子大于等于1时，patch会忽略上下文的第一行和最后一行，进行扫描和匹配。
如果仍旧不匹配，且最大模糊因子大于等于2，patch会忽略上下文的前两行和后两行来扫描和匹配(默认模糊因子为2)。
如果patch找不任何位置来安放当前块，它就会将这个块输出给reject文件----命名为生成文件加.rej后缀或#(如果文件名太长)。
当前块的行号在reject文件中可以不同于patch中的。因为reject文件中的行号表示的是patch认为这个匹配失败的块在新文件中大概的位置。
As each hunk is completed, you are told if the hunk failed, and if so which line (in the new file) patch thought the hunk should go on. If the hunk is installed at a different line from the line number specified in the diff you are told the offset. A single large offset may indicate that a hunk was installed in the wrong place. You are also told if a fuzz factor was used to make the match, in which case you should also be slightly suspicious. If the --verbose option is given, you are also told about hunks that match exactly.
当每个块都被处理后，Patch将会报告这个块是否失败了，这个块应该被补到哪行。如果块被安装在和diff文件中不同的行，一个很大的偏移量值为指示这个块被安装在了错误的位置。Patch还会报告是否使用了模糊因子，这时你对匹配结果应该保持一定的怀疑，有必要去检查一下。如果指定了“--verbose”选项，Patch会报告精确匹配的块。
If no original file origfile is specified on the command line, patch tries to figure out from the leading garbage what the name of the file to edit is, using the following rules.
如果在命令行中没有指定源文件origfile，Patch将会从头部的冗余信息中指出当前下在编辑的文件名，使用如下的规则：
First, patch takes an ordered list of candidate file names as follows:
Patch会使用如下的候选有序文件名列表：
· If the header is that of a context diff, patch takes the old and new file names in the header. A name is ignored if it does not have enough slashes to satisfy the -pnum or --strip=num option. The name /dev/null is also ignored.
如要头部是上下文diff，Patch会采用头部的旧的和新的文件名。当文件名不满足“-pnum”,“--strip=num”选项时将被忽略。文件名“/dev/null”也会被忽略。
· If there is an Index: line in the leading garbage and if either the old and new names are both absent or
if patch is conforming to POSIX, patch takes the name in the Index: line.
如果有一个索引：行号在头部的冗余信息中且旧文件名和新文件都不存在，或者Patch运行在POSIX系统上，Patch使用的名字为"Index::line"。
· For the purpose of the following rules, the candidate file names are considered to be in the order (old,
new, index), regardless of the order that they appear in the header.
以下规则的目的是为了使候选文件名有序--老的，新的，索引。而不是以它们在头中出现的顺序。
Then patch selects a file name from the candidate list as follows:
Patch从候选列表中选择文件外的规则如下：
· If some of the named files exist, patch selects the first name if conforming to POSIX, and the best name
otherwise.
如果文件名存在，Patch会选择第一个文件名
· If patch is not ignoring RCS, ClearCase, and SCCS (see the -g num or --get=num option), and no named
files exist but an RCS, ClearCase, or SCCS master is found, patch selects the first named file with an
RCS, ClearCase, or SCCS master.
· If no named files exist, no RCS, ClearCase, or SCCS master was found, some names are given, patch is not
conforming to POSIX, and the patch appears to create a file, patch selects the best name requiring the
creation of the fewest directories.
· If no file name results from the above heuristics, you are asked for the name of the file to patch, and
patch selects that name.
如果文件名不满足上面任何一条规则，Patch将会询问问题名，并采纳
To determine the best of a nonempty list of file names, patch first takes all the names with the fewest path name components; of those, it then takes all the names with the shortest basename; of those, it then takes all the shortest names; finally, it takes the first remaining name.
为了确定一个最好的非空文件名，patch先选择最短的路径名
Additionally, if the leading garbage contains a Prereq: line, patch takes the first word from the prerequisites line (normally a version number) and checks the original file to see if that word can be found. If not, patch asks for confirmation before proceeding.
The upshot of all this is that you should be able to say, while in a news interface, something like the following:
| patch -d /usr/src/local/blurfl
and patch a file in the blurfl directory directly from the article containing the patch.
If the patch file contains more than one patch, patch tries to apply each of them as if they came from sep-
arate 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 contains interest-
ing things such as file names and revision level, as mentioned previously.
OPTIONS
-b or --backup
Make backup files. That is, when patching a file, rename or copy the original instead of removing it.
When backing up a file that does not exist, an empty, unreadable backup file is created as a placeholder
to represent the nonexistent file. See the -V or --version-control option for details about how backup
file names are determined.
生成备份文件。
--backup-if-mismatch
Back up a file if the patch does not match the file exactly and if backups are not otherwise requested.
This is the default unless patch is conforming to POSIX.
当有文件不匹配时生成备份文件
--no-backup-if-mismatch
Do not back up a file if the patch does not match the file exactly and if backups are not otherwise
requested. This is the default if patch is conforming to POSIX.
当文件不匹配时也不生成备份文件
-B pref or --prefix=pref
Prefix pref to a file name when generating its simple backup file name. For example, with -B /junk/ the
simple backup file name for src/patch/util.c is /junk/src/patch/util.c.
指定备份文件名的前缀，如，使用 -B /junk 对于文件 src/patch/util.c的备份文件名为 /junk/src/patch/util.c
--binary
Read and write all files in binary mode, except for standard output and /dev/tty. This option has no
effect on POSIX-conforming systems. On systems like DOS where this option makes a difference, the patch
should be generated by diff -a --binary.
对所有的文件以二进制方式读和写，对应的补丁的生成要使用"diff -a --binary"。
-c or --context
Interpret the patch file as a ordinary context diff.
以普通上下文diff方式解析补丁文件。
-d dir or --directory=dir
Change to the directory dir immediately, before doing anything else.
在所有动作之前，改变当前文件路径
-D define or --ifdef=define
Use the #ifdef ... #endif construct to mark changes, with define as the differentiating symbol.
用"#ifdef ... #endif "来标记改变
--dry-run
Print the results of applying the patches without actually changing any files.
不对文件作任何修改，仅模拟打印出patch后的结果
-e or --ed
Interpret the patch file as an ed script.
将补丁文件解析成ed脚本
-E or --remove-empty-files
Remove output files that are empty after the patches have been applied. Normally this option is unnec-
essary, since patch can examine the time stamps on the header to determine whether a file should exist
after patching. However, if the input is not a context diff or if patch is conforming to POSIX, patch
does not remove empty patched files unless this option is given. When patch removes a file, it also
attempts to remove any empty ancestor directories.
删除在patch后为空的输出文件。通常来说，这个选项是不必要，因为patch为检查头部的时间戳来决定这 个文件在patch后是不是应该存在。但是，它在输入文件不是上下文diff或在POSIX系统中是有用。
-f or --force
Assume that the user knows exactly what he or she is doing, and do not ask any questions. Skip patches
whose headers do not say which file is to be patched; patch files even though they have the wrong ver-
sion for the 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 -s for that.
当用户很明确它所要做的工作时，可用此选项来忽略各项提示和询问
-F num or --fuzz=num
Set the maximum fuzz factor. This option only applies to diffs that have context, and causes patch 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.
设置模糊因子，该选项仅用于context diff，以使在patch匹配时忽略要安装块的行数。要注意，大模糊因子 会增加补丁出错的机率。默认的模糊因子为2。它的值不能大于补丁块的行数。通常设置为3
-g num or --get=num
This option controls patch's actions when a file is under RCS or SCCS control, and does not exist or is read-only and matches the default version, or when a file is under ClearCase control and does not exist. If num is positive, patch gets (or checks out) the file from the revision control system; if zero, patch ignores RCS, ClearCase, and SCCS and does not get the file; and if negative, patch asks the user whether to get the file. The default value of this option is given by the value of the PATCH_GET environment variable if it is set; if not, the default value is zero if patch is conforming to POSIX, negative otherwise.
配合版本控制工具RCS,SCCS, ClearCase来设置patch的动作，
--help
Print a summary of options and exit.
-i patchfile or --input=patchfile
Read the patch from patchfile. If patchfile is -, read from standard input, the default.
从文件“patchfile”来读取补丁。如果“patchfile”是“-”，则从标准输入读取
-l or --ignore-whitespace
Match patterns loosely, in case tabs or spaces have been munged in your files. Any sequence of one or
more blanks in the patch file matches any sequence in the original file, and sequences of blanks at the
ends of lines are ignored. Normal characters must still match exactly. Each line of the context must
still match a line in the original file.
放松匹配模式，忽略Tab，和空格。
-n or --normal
Interpret the patch file as a normal diff.
将补丁文件解析成“normal diff”模式
-N or --forward
Ignore patches that seem to be reversed or already applied. See also -R.
忽略已打补丁的地方
-o outfile or --output=outfile
Send output to outfile instead of patching files in place.
发送输出到文件“outfile”，而不是打补丁
-pnum or --strip=num
Strip the smallest prefix containing num leading slashes from each file name found in the patch file. A
sequence of one or more adjacent slashes is counted as a single slash. This controls how file names
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.
文件名前缀剥离
For example, supposing the file name in the patch file was
/u/howard/src/blurfl/blurfl.c
setting -p0 gives the entire file name unmodified,
-p0保持原样，不对文件名做任何修改
-p1 gives u/howard/src/blurfl/blurfl.c without the leading slash,
-p1剥离掉"/"，留下"u/howard/src/blurfl/blurfl.c"
-p4 gives blurfl/blurfl.c
-p4剥离掉"/"--1, "u/"--2, "howard/"--3, "src/"--4，留下"blurfl/blurfl.c"
and not specifying -p at all just gives you blurfl.c. Whatever you end up with is looked for either in
the current directory, or the directory specified by the -d option.
没有指定"-p"选项时，只留下"blurfl.c"。则patch查找的是当前路径或是"-d"指定的路径
--posix
Conform more strictly to the POSIX standard, as follows.
启用更强限制的POSIX标准
· Take the first existing file from the list (old, new, index) when intuiting file names from diff headers.
· Do not remove files that are empty after patching.
· Do not ask whether to get files from RCS, ClearCase, or SCCS.
· Require that all options precede the files in the command line.
· Do not backup files when there is a mismatch.
--quoting-style=word
Use style word to quote output names. The word should be one of the following:
风格化引用输出名
Literal
Output names as-is.
shell
Quote names for the shell if they contain shell metacharacters or would cause ambiguous output.
shell-always
Quote names for the shell, even if they would normally not require quoting.
c
Quote names as for a C language string.
escape Quote as with c except omit the surrounding double-quote characters.
You can specify the default value of the --quoting-style option with the environment variable QUOTING_STYLE. If that environment variable is not set, the default value is shell.
-r rejectfile or --reject-file=rejectfile
Put rejects into rejectfile instead of the default .rej file.
指定被patch拒绝的文件名
-R or --reverse
Assume 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.) patch attempts to swap each hunk around before applying it. Rejects come out in the swapped format. The -R option does not work with ed diff scripts
because there is too little information to reconstruct the reverse operation.
回滚补丁
If the first hunk of a patch fails, patch reverses the hunk to see if it can be applied that way. If it
can, you are asked if you want to have the -R option set. If it can't, the patch continues 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) since appends always succeed, due to the
fact that a null context matches anywhere. Luckily, most patches add or change lines rather than delete
them, so most reversed normal diffs begin with a delete, which fails, triggering the heuristic.)
-s or --silent or --quiet
Work silently, unless an error occurs.
静默工作模式，除非有错误发生
-t or --batch
Suppress questions like -f, but make some different assumptions: skip patches whose headers do not contain file names (the same as -f); 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.
像"-f"一样，抑制询问，但有一些不同的设定：
-T or --set-time
Set the modification and access times of patched files from time stamps given in context diff headers, assuming that the context diff headers use local time. This option is not recommended, because patches using local time cannot easily be used by people in other time zones, and because local time stamps are ambiguous when local clocks move backwards during daylight-saving time adjustments. Instead of using this option, generate patches with UTC and use the -Z or --set-utc option instead.
设置被打补丁文件的修改和访问时间
-u or --unified
-u or --unified
Interpret the patch file as a unified context diff.
以"unified context diff"模式解析补丁文件
-v or --version
Print out patch's revision header and patch level, and exit.
-V method or --version-control=method
Use method to determine backup file names. The method can also be given by the PATCH_VERSION_CONTROL
(or, if that's not set, the VERSION_CONTROL) environment variable, which is overridden by this option.
The method does not affect whether backup files are made; it affects only the names of any backup files
that are made.
以method方式确定备份文件名
The value of method is like the GNU Emacs 'version-control' variable; patch also recognizes synonyms that are more descriptive. The valid values for method are (unique abbreviations are accepted):
existing or nil
Make numbered backups of files that already have them, otherwise simple backups. This is the default.
numbered or t
Make numbered backups. The numbered backup file name for F is F.~N~ where N is the version number.
simple or never
Make simple backups. The -B or --prefix, -Y or --basename-prefix, and -z or --suffix options specify the simple backup file name. If none of these options are given, then a simple backup suffix is used; it is the value of the SIMPLE_BACKUP_SUFFIX environment variable if set, and is .orig otherwise.
With numbered or simple backups, if the backup file name is too long, the backup suffix ~ is used
instead; if even appending ~ would make the name too long, then ~ replaces the last character of the
file name.
--verbose
Output extra information about the work being done.
输出patch动作的额外信息
-x num or --debug=num
Set internal debugging flags of interest only to patch patchers.
-Y pref or --basename-prefix=pref
Prefix pref to the basename of a file name when generating its simple backup file name. For example,
with -Y .del/ the simple backup file name for src/patch/util.c is src/patch/.del/util.c.
在文件名的基名字添加前缀,如，对"src/patch/util.c"用"-Y .del/ ",则结果为"src/patch/.del/util.c"
-z suffix or --suffix=suffix
Use suffix as the simple backup suffix. For example, with -z - the simple backup file name for src/patch/util.c is src/patch/util.c-. The backup suffix may also be specified by the SIMPLE_BACKUP_SUFFIX environment variable, which is overridden by this option.
在文件名后添加后缀，如，对"src/patch/util.c"用"-z -",则结果为"src/patch/util.c-"。
-Z or --set-utc
Set the modification and access times of patched files from time stamps given in context diff headers,
assuming that the context diff headers use Coordinated Universal Time (UTC, often known as GMT). Also
see the -T or --set-time option.
给被打补丁的文件设置UTC格式的时间戳
The -Z or --set-utc and -T or --set-time options normally refrain from setting a file's time if the
file's original time does not match the time given in the patch header, or if its contents do not match
the patch exactly. However, if the -f or --force option is given, the file time is set regardless.
Due to the limitations of diff output format, these options cannot update the times of files whose contents have not changed. Also, if you use these options, you should remove (e.g. with make clean) all files that depend on the patched files, so that later invocations of make do not get confused by the patched files' times.
ENVIRONMENT
PATCH_GET
This specifies whether patch gets missing or read-only files from RCS, ClearCase, or SCCS by default;
see the -g or --get option.
POSIXLY_CORRECT
If set, patch conforms more strictly to the POSIX standard by default: see the --posix option.
QUOTING_STYLE
Default value of the --quoting-style option.
SIMPLE_BACKUP_SUFFIX
Extension to use for simple backup file names instead of .orig.
TMPDIR, TMP, TEMP
Directory to put temporary files in; patch uses the first environment variable in this list that is set.
If none are set, the default is system-dependent; it is normally /tmp on Unix hosts.
VERSION_CONTROL or PATCH_VERSION_CONTROL
Selects version control style; see the -v or --version-control option.
FILES
$TMPDIR/p*
temporary files
/dev/tty
controlling terminal; used to get answers to questions asked of the user
SEE ALSO
diff(1), ed(1)
Marshall T. Rose and Einar A. Stefferud, Proposed Standard for Message Encapsulation, Internet RFC 934
NOTES FOR PATCH SENDERS
There are several things you should bear in mind if you are going to be sending out patches.
Create your patch systematically. A good method is the command diff -Naur old new where old and new iden-
tify the old and new directories. The names old and new should not contain any slashes. The diff com-
mand's headers should have dates and times in Universal Time using traditional Unix format, so that patch
recipients can use the -Z or --set-utc option. Here is an example command, using Bourne shell syntax:
LC_ALL=C TZ=UTC0 diff -Naur gcc-2.7 gcc-2.8
Tell your recipients how to apply the patch by telling them which directory to cd to, and which patch
options to use. The option string -Np1 is recommended. Test your procedure by pretending to be a recipi-
ent and applying your patch to a copy of the original files.
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 patch file you send out. If you put a Prereq: line in with the patch, it
won't let them apply patches out of order without some warning.
You can create a file by sending out a diff that compares /dev/null or an empty file dated the Epoch
(1970-01-01 00:00:00 UTC) to the file you want to create. This only works if the file you want to create
doesn't exist already in the target directory. Conversely, you can remove a file by sending out a context
diff that compares the file to be deleted with an empty file dated the Epoch. The file will be removed
unless patch is conforming to POSIX and the -E or --remove-empty-files option is not given. An easy way to
generate patches that create and remove files is to use GNU diff's -N or --new-file option.
If the recipient is supposed to use the -pN option, do not send output that looks like this:
diff -Naur v2.0.29/prog/README prog/README
--- v2.0.29/prog/README Mon Mar 10 15:13:12 1997
+++ prog/README Mon Mar 17 14:58:22 1997
because the two file names have different numbers of slashes, and different versions of patch interpret the
file names differently. To avoid confusion, send output that looks like this instead:
diff -Naur v2.0.29/prog/README v2.0.30/prog/README
--- v2.0.29/prog/README Mon Mar 10 15:13:12 1997
+++ v2.0.30/prog/README Mon Mar 17 14:58:22 1997
Avoid sending patches that compare backup file names like README.orig, since this might confuse patch into
patching a backup file instead of the real file. Instead, send patches that compare the same base file
names in different directories, e.g. old/README and new/README.
Take care not to send out reversed patches, since it makes people wonder whether they already applied the
patch.
Try not to have your patch modify derived files (e.g. the file configure where there is a line configure:
configure.in in your makefile), since the recipient should be able to regenerate the derived files anyway.
If you must send diffs of derived files, generate the diffs using UTC, have the recipients apply the patch
with the -Z or --set-utc option, and have them remove any unpatched files that depend on patched files
(e.g. with make clean).
While you may be able to get away with putting 582 diff listings into one file, it may be wiser to group
related patches into separate files in case something goes haywire.
DIAGNOSTICS
Diagnostics generally indicate that patch couldn't parse your patch file.
If the --verbose option is given, the message Hmm... indicates that there is unprocessed text in the patch
file and that patch is attempting to intuit whether there is a patch in that text and, if so, what kind of
patch it is.
patch's exit status is 0 if all hunks are applied successfully, 1 if some hunks cannot be applied, and 2 if
there is more serious trouble. 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.
CAVEATS
Context diffs cannot reliably represent the creation or deletion of empty files, empty directories, or spe-
cial files such as symbolic links. Nor can they represent changes to file metadata like ownership, permis-
sions, or whether one file is a hard link to another. If changes like these are also required, separate
instructions (e.g. a shell script) to accomplish them should accompany the patch.
patch cannot tell if the line numbers are off in an ed script, and can detect bad line numbers in a normal
diff only when it finds a change or deletion. A context diff using fuzz factor 3 may have the same prob-
lem. 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.
patch 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.
COMPATIBILITY ISSUES
The POSIX standard specifies behavior that differs from patch's traditional behavior. You should be aware
of these differences if you must interoperate with patch versions 2.1 and earlier, which do not conform to
POSIX.
· In traditional patch, the -p option's operand was optional, and a bare -p was equivalent to -p0. The -p
option now requires an operand, and -p 0 is now equivalent to -p0. For maximum compatibility, use
options like -p0 and -p1.
Also, traditional patch simply counted slashes when stripping path prefixes; patch now counts pathname
components. That is, a sequence of one or more adjacent slashes now counts as a single slash. For max-
imum portability, avoid sending patches containing // in file names.
· In traditional patch, backups were enabled by default. This behavior is now enabled with the -b or
--backup option.
Conversely, in POSIX patch, backups are never made, even when there is a mismatch. In GNU patch, this
behavior is enabled with the --no-backup-if-mismatch option, or by conforming to POSIX with the --posix
option or by setting the POSIXLY_CORRECT environment variable.
The -b suffix option of traditional patch is equivalent to the -b -z suffix options of GNU patch.
· Traditional patch used a complicated (and incompletely documented) method to intuit the name of the file
to be patched from the patch header. This method did not conform to POSIX, and had a few gotchas. Now
patch uses a different, equally complicated (but better documented) method that is optionally POSIX-con-
forming; we hope it has fewer gotchas. The two methods are compatible if the file names in the context
diff header and the Index: line are all identical after prefix-stripping. Your patch is normally com-
patible if each header's file names all contain the same number of slashes.
· When traditional patch asked the user a question, it sent the question to standard error and looked for
an answer from the first file in the following list that was a terminal: standard error, standard out-
put, /dev/tty, and standard input. Now patch sends questions to standard output and gets answers from
/dev/tty. Defaults for some answers have been changed so that patch never goes into an infinite loop
when using default answers.
· Traditional patch exited with a status value that counted the number of bad hunks, or with status 1 if
there was real trouble. Now patch exits with status 1 if some hunks failed, or with 2 if there was real
trouble.
· Limit yourself to the following options when sending instructions meant to be executed by anyone running
GNU patch, traditional patch, or a patch that conforms to POSIX. Spaces are significant in the follow-
ing list, and operands are required.
-c
-d dir
-D define
-e
-l
-n
-N
-o outfile
-pnum
-R
-r rejectfile
BUGS
Please report bugs via email to
patch could be smarter about partial matches, excessively deviant offsets and swapped code, but that would
take an extra pass.
If code has been duplicated (for instance with #ifdef OLDCODE ... #else ... #endif), patch is incapable of
patching both versions, and, if it works at all, will likely patch the wrong one, and tell you that it suc-
ceeded to boot.
If you apply a patch you've already applied, patch thinks it is a reversed patch, and offers to un-apply
the patch. This could be construed as a feature.
COPYING
Copyright 1984, 1985, 1986, 1988 Larry Wall.
Copyright 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice
and this permission notice are preserved on all copies.
Permission is granted to copy and distribute modified versions of this manual under the conditions for ver-
batim copying, provided that the entire resulting derived work is distributed under the terms of a permis-
sion notice identical to this one.
Permission is granted to copy and distribute translations of this manual into another language, under the
above conditions for modified versions, except that this permission notice may be included in translations
approved by the copyright holders instead of in the original English.
AUTHORS
Larry Wall wrote the original version of patch. Paul Eggert removed patch's arbitrary limits; added sup-
port for binary files, setting file times, and deleting files; and made it conform better to POSIX. Other
contributors include Wayne Davison, who added unidiff support, and David MacKenzie, who added configuration
and backup support.
GNU 1998/03/21 PATCH(1)
