PATCH(1) | General Commands Manual | PATCH(1) |
patch
— apply a
diff file to an original
patch |
[-bCcEeflNnRstuv ]
[-B backup-prefix]
[-D symbol]
[-d directory]
[-g vcs-option]
[-F max-fuzz]
[-i patchfile]
[-o out-file]
[-p strip-count]
[-r rej-name]
[-T | -Z ]
[-V t | nil | never | none ]
[-x number]
[-Y prefix]
[-z backup-ext]
[--quoting-style style]
[--posix ]
[origfile [patchfile]] |
patch |
<patchfile |
patch
will take a patch file containing
any of the four forms of difference listing produced by the
diff(1) program and apply those
differences to an original file, producing a patched version. If
patchfile is omitted, or is a hyphen, the patch will
be read from the standard input.
patch
will attempt to determine the type
of the diff listing, unless overruled by a -c
,
-e
, -n
, or
-u
option. Context diffs (old-style, new-style, and
unified) and normal diffs are applied directly by the
patch
program itself, whereas ed diffs are simply
fed to the ed(1) editor via a pipe.
If the patchfile contains more than one
patch, patch
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 file names and revision level (see the
section on Filename
Determination below).
The options are as follows:
-B
backup-prefix, --prefix
backup-prefix-z
will be ignored.-b
,
--backup
-V
existing
".--backup-if-mismatch
-b
option,
--backup-if-mismatch
will use the
existing
format that is accepted by the
-V
option when a backup is to be created.
If backups were otherwise requested with the
-b
option, then this option has no effect.
This option is currently the default, unless
--posix
is specified.
--no-backup-if-mismatch
--backup-if-mismatch
, creating
backups for every file unless backups have been disabled with
--posix
or -V
none
.-C
,
--check
, --dry-run
-c
,
--context
patch
to interpret the patch file as a
context diff.-D
symbol, --ifdef
symbolpatch
to use the
"#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
-D
and the argument.-d
directory, --directory
directorypatch
to interpret the next argument as a
directory, and change the working directory to it before doing anything
else.-E
,
--remove-empty-files
patch
to remove output files that are empty
after the patches have been applied. This option is useful when applying
patches that create or remove files.-e
,
--ed
patch
to interpret the patch file as an
ed(1) script.-F
max-fuzz, --fuzz
max-fuzzpatch
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.-f
,
--force
patch
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 cannot 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. This option does not suppress commentary; use
-s
for that.-g
vcs-option, --get
vcs-optionpatch
to consult some version control
systems for missing or read-only files. This version of
patch
has limited, detect-only support for SCCS
and ClearCase, but full support for RCS and Perforce.
If vcs-option is set to 0, then
patch
will not consult any version control
system. This is the default behavior, unless overruled by setting the
PATCH_GET
environment variable.
If vcs-option is set to a negative
number, then patch
will prompt to confirm that
it is OK to checkout each file that is detected under a supported
version control system.
If vcs-option is set to a positive
number, then patch
will not prompt before
checking out each file that is detected under a supported version
control system.
Note that one must be in the root directory of the repository
in order for --get
to work, unless
patch
is operating in a Perforce workspace.
The --get
option may also influence
how a filename is chosen. See
Filename Determination
below for details.
--help
-i
patchfile, --input
patchfile-l
,
--ignore-whitespace
-N
,
--forward
patch
to ignore patches that it thinks are
reversed or already applied. See also -R
.-n
,
--normal
patch
to interpret the patch file as a
normal diff.-o
out-file, --output
out-file-p
strip-count, --strip
strip-countSetting -p
0
gives the entire pathname unmodified.
-p
1 gives
without the leading slash.
-p
4 gives
Not specifying -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, 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 -d
option.
--quoting-style
stylepatch
writes out filenames to the
console. The valid values for style are:
literal
shell
shell-always
c
escape
c
, except quotes will be
omitted.The default quoting option is shell
,
unless QUOTING_STYLE
is set.
-R
,
--reverse
patch
that this patch was created with the
old and new files swapped. (Yes, I am afraid that does happen
occasionally, human nature being what it is.)
patch
will attempt to swap each hunk around before
applying it. Rejects will come out in the swapped format. The
-R
option will 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
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
-R
option set. If it cannot, 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) since appends always
succeed, due to the fact that a null context will match 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.)
-r
rej-name, --reject-file
rej-name-s
,
--quiet
, --silent
patch
do its work silently, unless an error
occurs.-T
,
--set-time
patch
to set the access and modification
times of the output file based on timestamps included in the diff's
header. The -T
option will force
patch
to assume the timestamps provided are in the
system's local timezone, unless a timezone offset is present in the
timstamp.
patch
will not change the times on the
output file unless the original file's timestamp matches the proper
file's timestamp in the diff header and the patch context matched the
original file with neither fuzz nor offsets. Both of these caveats are
ignored if the -f
flag has been specified.
-t
,
--batch
-f
, in that it suppresses questions,
but makes some different assumptions: skip patches for which a file to
patch cannot be found (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.-u
,
--unified
patch
to interpret the patch file as a
unified context diff (a unidiff).-V
t
|
nil
|
never
|
none
,
--version-control
t
|
nil
|
never
|
none
PATCH_VERSION_CONTROL
or
VERSION_CONTROL
environment variables, which are
overridden by this option. The -B
option overrides
this option, causing the prefix to always be used for making backup file
names. The values of the PATCH_VERSION_CONTROL
and
VERSION_CONTROL
environment variables and the
argument to the -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):
-v
,
--version
patch
to print out its revision header and
patch level.-x
number, --debug
numberpatch
patchers.-Y
prefix, --basename-prefix
prefix-Z
,
--set-utc
patch
to set the access and modification
times of the output file based on timestamps included in the diff's
header. The -Z
option will force
patch
to assume the timestamps provided are in UTC
unless the timezone offset is present in the timstamp. Note that the
caveats described with the -T
option about when
the output file's modification time is changed also apply to the
-Z
option.-z
backup-ext, --suffix
backup-ext--posix
-b
option is specified.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
patch
, and it should work. If the entire diff is
indented by a consistent amount, this will be 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 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, patch
will scan
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 is 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 will put the hunk out to a reject file, which
normally is the name of the output file plus ".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.
As each hunk is completed, you will be told whether the hunk
succeeded or failed, and which line (in the new file)
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.
If no original file is specified on the command line,
patch
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
-p
option and the file's existence and writability
are checked relative to the current working directory (or the directory
specified by the -d
option).
If the diff is a context or unified diff,
patch
is able to determine the old and new file
names from the diff header. For context diffs, the “old” file
is specified in the line beginning with "***" and the
“new” file is specified in the line beginning with
"---". For a unified diff, the “old” file is
specified in the line beginning with "---" and the
“new” file is specified in the line beginning with
"+++". If there is an "Index": line in the leading
garbage (regardless of the diff type), patch
will
use the file name from that line as the “index” file.
patch
will choose the file name by
performing the following steps, with the first match used:
patch
is operating in strict
IEEE Std 1003.1-2008 (“POSIX.1”)
mode, the first of the “old”, “new” and
“index” file names that exist is used.patch
is not operating in strict
IEEE Std 1003.1-2008 (“POSIX.1”)
mode, and a non-zero --get
argument has been
supplied, then patch
will choose one of the
“index”, “old” or “new”
filenames that are detected to exist under a version control system.
Otherwise, patch
will examine either the
“old” and “new” file names or, for a
non-context diff, the “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).patch
will prompt the user for the file name to use.Additionally, if the leading garbage contains a
"Prereq: " line, 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,
patch
will ask for confirmation before
proceeding.
The upshot of all this is that you should be able to say, while in a news interface, the following:
| patch -d
/usr/src/local/blurfl
and patch a file in the blurfl directory directly from the article containing the patch.
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
".orig", or as specified by the -B
,
-V
, or -z
options. The
extension used for making backup files may also be specified in the
SIMPLE_BACKUP_SUFFIX
environment variable, which is
overridden by the options above.
If the backup file is a symbolic or hard link to the original
file, 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 or is not linked to
the original file.
You may also specify where you want the output to go with the
-o
option; if that file already exists, it is backed
up first.
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 patch file you send out. If you put a "Prereq": line in with the patch, it will not let them apply patches out of order without some warning.
Second, make sure you have specified the file names right, either
in a context diff header, or with an "Index": line. If you are
patching something in a subdirectory, be sure to tell the patch user to
specify a -p
option as needed.
Third, you can create a file by sending out a diff that compares a
null file to the file you want to create. If the file you want to create
already exists in the target directory when the diff is applied, then
patch
will identify the patch as potentially
reversed and offer to reverse the patch.
Fourth, take care not to send out reversed patches, since it makes people wonder whether they already applied the patch.
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.
PATCH_GET
--get
for valid values.PATCH_VERBOSE
patch
. Setting
PATCH_VERBOSE
to a non-zero integer will enable
verbosity.POSIXLY_CORRECT
patch
behaves as if the
--posix
option has been specified.QUOTING_STYLE
--quoting-style
for valid values.SIMPLE_BACKUP_SUFFIX
TMPDIR
PATCH_VERSION_CONTROL
VERSION_CONTROL
PATCH_VERSION_CONTROL
.patch
temporary filespatch
prompts the
userThe patch
utility exits with one of the
following values:
When applying a set of patches in a loop it behooves you to check this exit status so you do not apply a later patch to a partially patched file.
Too many to list here, but generally indicative that
patch
couldn't parse your patch file.
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.
The patch
utility is compliant with the
IEEE Std 1003.1-2008 (“POSIX.1”)
specification, except as detailed above for the
--posix
option.
The flags [-BCEFfstVvxz
] and
[--posix
] are extensions to that specification.
Larry Wall with many other contributors.
patch
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 "change" or a "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.
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.
Could be smarter about partial matches, excessively deviant offsets and swapped code, but that would take an extra pass.
Check patch mode (-C
) will fail if you try
to check several patches in succession that build on each other. The entire
patch
code would have to be restructured to keep
temporary files around so that it can handle this situation.
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 have already applied,
patch
will think it is a reversed patch, and offer
to un-apply the patch. This could be construed as a feature.
April 27, 2022 | macOS 14.6 |