patch
apply a diff file to an original
see also :
diff - ed
Synopsis
patch
[options] [originalfile
[patchfile]]
but usually
just
patch
-pnum <patchfile
add an example, a script, a trick and tips
examples
source
diff and patch tool
Although I've never used Meld, I have a feeling it's actually
using 'diff' under the covers. The way I've always generated
patch files is simple:
$ diff -ruN ${dir1} ${dir2} > ${patchfile}.patch
That generates a single large patch file, which you can then
break up as apporpriate. To generate individual patch files for
each change found, you would simply run that large file through a
script that split when it saw a new changeset (a script I don't
have handy or know of, since I've never used one like it).
source
Binary diff/patch for large files on linux?
You should probably take a look at the rsync-related tools:
rdiff and rdiff-backup. The
rdiff
command lets you produce a patch file and
apply it to some other file.
The rdiff-backup
command uses this approach to deal
with entire directories, but I'm guessing you're working with
single-file disk images, so rdiff
will be the one to
use.
source
How to apply patch to Gnome on Ubuntu
apt-get build-dep gnome-terminal
apt-get source gnome-terminal
wget -c https://bugs.launchpad.net/ubuntu/+source/gnome-terminal/+bug/526437/+attachment/1285690/+files/save-contents-keyentry.patch
cd gnome-terminal-2.29.6/
cp ../save-contents-keyentry.patch debian/patches/30_save_contents_keyentry.patch
dpkg-buildpackage -b
Or wait a bit, and it'll build in my ppa
source
Do distributions like Ubuntu and Fedora costomize their own kernels?
Yes, all major distributions customizes their kernel. I use
Mandriva Linux and they have some 500 patches to the kernel, but
the system works well with the Vanilla (original) kernel, too.
Usually the last number, in your case 21, shows the build number
of your customized kernel. In other words, Ubuntu built 21
different kernels from the original sources of 2.6.31 until they
reached the current state.
Some directories are also customized to let applications
differentiate between several kernels if you have more than one
installed.
source
Atomic application of unix patch
git apply
can be used for this. It
does not require a Git repository.
source
How do I apply a patch to my Linux kernel?
Your Linux distribution usually has its own instructions. Search
their website or ask on IRC – or at least tell us the distro;
without knowing it, it's impossible to provide a reliable anwer.
The generic instructions are:
-
Download the kernel source from Kernel.org. "Stable" is probably the best
choice. Extract to a convenient place (I use
~/src/linux
).
-
Read the file named
README
.
-
Once inside the source directory, copy the current kernel's
configuration, with:
zcat /proc/config.gz > .config
-
Apply the patch, with:
patch -p1 < foo.patch
(try -p0
if it gets rejected).
-
Compile the kernel with:
make silentoldconfig && make
-
Install the modules with:
sudo make modules_install
-
Install the kernel image
.../linux/arch/i386/boot/bzImage
to whatever
location your bootloader looks in.
source
What do these instructions mean in plain English?
Unified diff format: basically '-' means removed
line, '+' means added line. So you can manually apply the patch
if you want. But the best thing would be to resolve the
underlying problem. Is the file segment you provide the complete
file? If it is - it indicates that the diff header information is
corrupt/missing, and you need to go back to the
source/tools/process that created this patch.
source
Arch Linux: How to handle patches which only you will use?
Try reporting a bug to the original author, and if your patch
adds something like a configuration option to choose if disable
that or not, they might accept it.
If they don't accept your patch, the only option is to re-patch
and re-compile at every release they do.
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 be specified on the command line as
originalfile.
Upon startup,
patch attempts to determine the type of the diff listing,
unless overruled by a -c
(--context), -e
(--ed), -n
(--normal), or -u
(--unified) option. Context diffs
(old-style, new-style, and unified) 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, if lines end in CRLF , or if a diff
is encapsulated one or more times by prepending
"- " to lines starting with
"-" as specified by Internet RFC 934,
this is taken into account. After removing indenting or
encapsulation, lines beginning with # are ignored, as
they are considered to be comments.
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. 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.)
Hunks with less
prefix context than suffix context (after applying fuzz)
must apply at the start of the file if their first line
number is 1. Hunks with more prefix context than suffix
context (after applying fuzz) must apply at the end of the
file.
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 unified or context diff format. 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.
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.
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.
First,
patch takes an ordered list of candidate file names
as follows:
•
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.
•
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.
•
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.
Then
patch selects a file name from the candidate list as
follows:
•
If some of the named files
exist, patch selects the first name if conforming to
POSIX , and the best name otherwise.
•
If patch is not ignoring RCS ,
ClearCase, Perforce, and SCCS (see the
-g num or
--get=num option), and no named
files exist but an RCS , ClearCase, Perforce,
or SCCS master is found, patch selects
the first named file with an RCS , ClearCase,
Perforce, or SCCS master.
•
If no named files exist, no RCS ,
ClearCase, Perforce, 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.
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.
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 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 contains interesting 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. See the -V or
--version-control option for
details about how backup file names are determined.
--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 .
--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 .
-B pref or
--prefix=pref
Use the simple method to
determine backup file names (see the -V
method or --version-control
method option), and append pref to a file name
when generating its backup file name. For example, with
-B /junk/ the simple backup file name for
src/patch/util.c is
/junk/src/patch/util.c.
--binary
Write all files in binary mode,
except for standard output and /dev/tty. When
reading, disable the heuristic for transforming CRLF line
endings into LF line endings. This option is needed on
POSIX systems when applying patches generated
on non- POSIX systems to non-
POSIX files. (On POSIX
systems, file reads and writes never transform line endings.
On Windows, reads and writes do transform line endings by
default, and patches should be generated by
diff --binary when line endings are
significant.)
-c or
--context
Interpret the patch file as a
ordinary context diff.
-d dir or
--directory=dir
Change to the directory
dir immediately, before doing anything else.
-D define
or --ifdef=define
Use the #ifdef ...
#endif construct to mark changes, with define
as the differentiating symbol.
--dry-run
Print the results of applying
the patches without actually changing any files.
-e or
--ed
Interpret the patch file as an
ed script.
-E or
--remove-empty-files
Remove output files that are
empty after the patches have been applied. Normally this
option is unnecessary, 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.
-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 version 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.
-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 of
context 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. A fuzz factor greater than or
equal to the number of lines of context in the context diff,
ordinarily 3, ignores all context.
-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 or Perforce 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, Perforce, 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.
--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.
-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.
--merge or
--merge=merge or
--merge=diff3
Merge a patch file into the
original files similar to diff3(1) or
merge(1). If a conflict is found, patch
outputs a warning and brackets the conflict with
<<<<<<< and
>>>>>>> lines. A typical
conflict will look like this:
<<<<<<<
lines from the original file
|||||||
original lines from the patch
=======
new lines from the patch
>>>>>>>
The optional argument of --merge
determines the output format for conflicts: the diff3 format
shows the ||||||| section with the original lines
from the patch; in the merge format, this section is
missing. The merge format is the default.
This option
implies --forward and does not take the
--fuzz=num option into account.
-n or
--normal
Interpret the patch file as a
normal diff.
-N or
--forward
Ignore patches that seem to be
reversed or already applied. See also -R.
-o outfile
or --output=outfile
Send output to outfile
instead of patching files in place. Do not use this option
if outfile is one of the files to be patched. When
outfile is -, send output to standard
output, and send any messages that would usually go to
standard output to standard error.
-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. 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,
-p1 gives
u/howard/src/blurfl/blurfl.c
without the
leading slash, -p4 gives
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.
--posix
Conform more strictly to the
POSIX standard, as follows.
•
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, Perforce, 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:
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.
When rejectfile is -, discard
rejects.
-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.
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.)
--reject-format=format
Produce reject files in the
specified format (either context or
unified). Without this option, rejected hunks come
out in unified diff format if the input patch was of that
format, otherwise in ordinary context diff form.
-s or
--silent or
--quiet
Work silently, unless an error
occurs.
-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.
-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.
-u or
--unified
Interpret the patch file as a
unified context diff.
-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.
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.
-x num or
--debug=num
Set internal debugging flags of
interest only to patch patchers.
-Y pref or
--basename-prefix=pref
Use the simple method to
determine backup file names (see the -V
method or --version-control
method option), and prefix pref to the
basename of a file name when generating its backup file
name. For example, with -Y .del/ the
simple backup file name for src/patch/util.c is
src/patch/.del/util.c.
-z suffix
or --suffix=suffix
Use the simple method to
determine backup file names (see the -V
method or --version-control
method option), and use suffix as the suffix.
For example, with -z - the backup file
name for src/patch/util.c is
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.
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.
caveats
Context diffs cannot reliably represent the creation or deletion
of empty files, empty directories, or special files such as
symbolic links. Nor can they represent changes to file metadata
like ownership, permissions, 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 problem. 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 maximum 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 -conforming; 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
compatible 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 output, /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
following list, and operands are required.
-c
-d dir
-D define
-e
-l
-n
-N
-o outfile
-pnum
-R
-r rejectfile
copying
Copyright (C) 1984, 1985, 1986, 1988 Larry Wall.
Copyright (C) 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996,
1997, 1998, 1999, 2000, 2001, 2002, 2009 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 verbatim copying, provided
that the entire resulting derived work is distributed under the
terms of a permission 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.
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 or there were
merge conflicts, 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.
environment
PATCH_GET
This specifies whether patch gets missing or read-only
files from RCS , ClearCase, Perforce, 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
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 identify the old and new directories. The names
old and new should not contain any slashes. The
diff command’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 recipient 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.
bugs
Please report
bugs via email to <bug-patch[:at:]gnu[:dot:]org>.
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 succeeded 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.
Computing how
to merge a hunk is significantly harder than using the
standard fuzzy algorithm. Bigger hunks, more context, a
bigger offset from the original location, and a worse match
all slow the algorithm down.
see also
diff ,
ed , merge.
Marshall T.
Rose and Einar A. Stefferud, Proposed Standard for Message
Encapsulation, Internet RFC 934
<URL:ftp://ftp.isi.edu/in-notes/rfc934.txt>
(1985-01).
authors
Larry Wall
wrote the original version of patch. Paul Eggert
removed patch’s arbitrary limits; added support
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. Andreas Grünbacher added support for
merging.