patch(1) patch(1)
NAME
patch - apply patch changes to files
SYNOPSIS
patch [-blNR] [-c| -e| -n] [-d dir] [-D define] [-i patchfile]
[-o outfile] [-p num] [-r rejectfile] [file]
DESCRIPTION
The patch utility reads a path or source file containing one
of the three forms of listings produced by the diff utility
and applies those differences to a file. By default, patch
reads from the standard input.
When the patch utility is run without specifying the -c, -e,
or -n option, patch tries to determine the type of diff list.
When a patch file contains more than one patch, each patch is
applied as if it came from a separate patch file. In this
case, the name of the patch file is determined from the diff
listing.
Patches that cannot be correctly placed in the file are
written to a reject file. The name of this file is formed by
appending the suffix to the original filename, unless the -r
option is present with a name for the reject file. Then, the
specified name overrides the default name.
file is the pathname of the patch file.
OPTIONS
The following options are supported:
-b Save a copy of the original file, in a file of the same
name with the suffix .orig appended to it. If the file
already exists, it is overwritten; if multiple patches
are applied to the same file, the .orig file is written
only for the first patch. When the -o outfile option
also is specified, file.orig is not created but, if
outfile already exists, outfile.orig is created.
-c Interpret the patch file as a context difference, that
is, it was created by the utility diff when the -c or
-C option was specified.
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patch(1) patch(1)
-d dir Change the current directory to dir before processing.
-D define
Mark changes with the C preprocessor construct:
#ifdef define
. . .
#endif
The option-argument define is used as the
differentiating symbol.
-e Interpret the path file as an ed script, rather than a
diff.
-i patchfile
Read the patch information from the file named by the
pathname patchfile, rather than the standard input.
-l Cause any sequence of blank characters in the difference
script to match any sequence of blank characters in the
input file. Other characters are matched exactly.
-n Interpret the script as a normal difference.
-N Ignore patches where the differences have already been
applied to the file; by default, already-applied
patches are rejected.
-o outfile
Instead of modifying the input file directly, write a
copy of the file referenced by each patch, with the
appropriate differences applied, to outfile. Multiple
patches for a single file are applied to the
intermediate versions of the file created by any
previous patches, and results in multiple, concatenated
versions of the file being written to outfile.
-p num For all pathnames in the patch file that show the names
of files to be patched, delete num pathname components
from the beginning of each pathname. If the pathname
in the patch file is absolute, any leading slashes are
considered the first component (that is, -p 1 removes
the leading slashes). Specifying -p 1 causes the full
pathname to be used. If -p is not specified, only the
basename (the final pathname component) is used.
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patch(1) patch(1)
-R Reverse the sense of the patch script; that is, assume
that the difference script was created from the new
version to the old version. The -R option cannot be
used with ed scripts. The patch utility attempts to
reverse each portion of the script before applying it.
Rejected differences are saved in swapped format. If
this option is not specified, and until a portion of
the patch file is successfully applied, patch attempts
to apply each portion in its reversed sense as well as
in its normal sense. If the attempt is successful, the
user is prompted to determine if the -R option should
be set.
-r rejectfile
Use rejectfile to override the default reject filename.
The default reject filename is the name of the output
file, with the suffix appended to it.
ENVIRONMENT VARIABLES
The following environment variables affect the execution of
patch:
LANG Provide a default value for the internationalization
variables that are unset or null. If LANG is unset or
null, the corresponding value from the implementation-
specific default locale is used. If any of the
internationalization variables contains an invalid
setting, the utility behaves as if none of the variables
had been defined.
LC_ALL
If set to a non-empty string value, override the values
of all the other internationalization variables.
LC_CTYPE
Determine the locale for the interpretation of sequences
of bytes of text data as characters (for example,
single- as opposed to multi-byte characters in arguments
and input files).
LC_MESSAGES
Determine the locale that should be used to affect the
format and contents of diagnostic messages written to
standard error and informative messages written to
standard output.
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patch(1) patch(1)
LC_TIME
Determine the locale for recognizing the format of file
timestamps written by the diff utility in a context-
difference input file.
Patchfile Format
The patch file must contain zero or more lines of header
information followed by one or more patches. Each patch must
contain zero or more lines of filename identification in the
format produced by diff -c, and one or more sets of diff
output, which are customarily called hunks.
The patch utility recognizes the following expression in the
header information:
Index: pathname The file to be patched is named pathname
If all lines (including headers) within a patch begin with the
same leading sequence of blank characters, the patch utility
removes this sequence before proceeding. Within each patch,
if the type of difference is context, the patch utility
recognizes the following expressions:
*** filename timestamp The patches arose from filename.
--- filename timestamp The patches should be applied to filename.
Each hunk within a patch must be the diff output to change a
line range within the original file. The line numbers for
successive hunks within a patch must occur in ascending order.
Filename Determination
If no file operand is specified, patch performs the following
steps to obtain a pathname:
If the patch contains the strings *** and --- patch utility
strips components from the beginning of each pathname and then
tests for the existence of both files in the current directory
or the directory specified with the -d option. If both files
exist, patch assumes that no pathname can be obtained from
this step.
If the header information contains a line with the string
Index:, patch strips components from the beginning of the
pathname and then tests for the existence of this file in the
current directory or the directory specified with the -d
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patch(1) patch(1)
option.
If no pathname can be obtained by applying the previous steps,
or if the pathnames obtained do not exist, patch writes a
prompt to standard output and requests a filename
interactively from standard input.
Patch Application
If the -c, -e, or -n option is present, the patch utility
interprets information within each hunk as a context
difference, an ed difference or a normal difference,
respectively. In the absence of any of these options, the
patch utility determines the type of difference based on the
format of information within the hunk.
For each hunk, the patch utility begins to search for the
place to apply the patch at the line number at the beginning
of the hunk, plus or minus an offset used in applying the
previous hunk. If line matching the hunk context are not
found, patch scans both forwards and backwards at least 1000
bytes for a set of lines that match the hunk context.
If no such place is found and it is a context difference, then
another scan takes place, ignoring the first and last line of
context. If that fails, the first two and last two lines of
context are ignored and another scan is made. Implementations
can search more extensively for installation locations.
If no location is found, the patch utility appends the hunk to
the reject file. The rejected hunk is written in contest-
difference format regardless of the format of the patch file.
If the input was a normal or ed-style difference, the reject
file can contain differences with zero line of context. The
line numbers on the hunks in the reject file can be different
from the line numbers in the patch file since they reflect the
approximate locations for the failed hunks in the new file
rather than the old one.
If the type of patch is an ed diff, the implementation can
accomplish the patching by invoking the ed utility.
NOTICES
The -R utility does not work with ed scripts because there is
too little information to reconstruct the reverse operation.
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patch(1) patch(1)
The -p option makes it possible to customize a patchfile to
local user directory structures without manually editing the
patchfile. For example, if the filename in the patch file
was:
/curds/whey/src/blurf1/blurf1.c
Setting -p 0 gives the entire pathname unmodified; -p 1 gives:
/curds/whey/src/blurf1/blurf1.c
without the leading slash, -p 4 gives:
blurf1/blurf1.c
and not specifying -p at all gives:
blurf1.c .
When using -b in some file system implementations, the saving
of a .orig file can produce unwanted results. In the case of
12, 13, or 14-character filenames, on file systems supporting
14-character maximum filenames, the .orig file overwrites the
new file.
REFERENCES
diff(1), ed(1)
Copyright 1994 Novell, Inc. Page 6