patch - apply changes to files
patch [-blNR] [-c | -e | -n | -u] [-d dir] [-D define] [-
i patchfile] [-o outfile] [-p num] [-r rejectfile] [file]
The patch command reads a source (patch) file containing any
of the three forms of difference (diff) listings produced by
the diff(1) command (normal, context or in the style of
ed(1)) and apply those differences to a file. By default,
patch reads from the standard input.
patch attempts to determine the type of the diff listing,
unless overruled by a -c, -e, or -n option.
If the patch file contains more than one patch, patch will
attempt to apply each of them as if they came from separate
patch files. (In this case the name of the patch file must
be determinable for each diff listing.)
The following options are supported:
-b Saves a copy of the original contents of each modified
file, before the differences are applied, in a file of
the same name with the suffix .orig appended to it. If
the file already exists, it will be overwritten. If
multiple patches are applied to the same file, the
.orig file will be written only for the first patch.
When the -o outfile option is also specified,
file.orig will not be created but, if outfile already
exists, outfile.orig will be created.
-c Interprets the patch file as a context difference (the
output of the command diff when the -c or -C options
Changes the current directory to dir before processing
as described in EXTENDED DESCRIPTION.
Marks changes with the C preprocessor construct:
The option-argument define will be used as the differentiat-
-e Interprets the patch file as an ed script, rather than
a diff script.
Reads the patch information from the file named by the
path name patchfile, rather than the standard input.
-l (The letter ell.) Causes any sequence of blank charac-
ters in the difference script to match any sequence of
blank characters in the input file. Other characters
will be matched exactly.
-n Interprets the script as a normal difference.
-N Ignores patches where the differences have already
been applied to the file; by default, already-applied
patches are rejected.
Instead of modifying the files (specified by the file
operand or the difference listings) directly, writes a
copy of the file referenced by each patch, with the
appropriate differences applied, to outfile. Multiple
patches for a single file will be applied to the
intermediate versions of the file created by any pre-
vious patches, and will result in multiple, con-
catenated versions of the file being written to out-
For all path names in the patch file that indicate the
names of files to be patched, deletes num path name
components from the beginning of each path name. If
the path name in the patch file is absolute, any lead-
ing slashes are considered the first component (that
is, -p 1 removes the leading slashes). Specifying -p 0
causes the full path name to be used. If -p is not
specified, only the basename (the final path name com-
ponent) is used.
-R Reverses the sense of the patch script. That is,
assumes that the difference script was created from
the new version to the old version. The -R option can-
not be used with ed scripts. patch attempts to reverse
each portion of the script before applying it.
Rejected differences will be 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 suc-
cessful, the user will be prompted to determine if the
-R option should be set.
Overrides the default reject file name. In the default
case, the reject file will have the same name as the
output file, with the suffix .rej appended to it. See
-u Interprets the patch file as a unified context differ-
ence, that is, the output of the command diff when the
-u or -U options are specified.
The following operand is supported:
file A path name of a file to patch.
The -R option will not work with ed scripts because there is
too little information to reconstruct the reverse operation.
The -p option makes it possible to customize a patch file to
local user directory structures without manually editing the
patch file. For example, if the file name in the patch file
o Setting -p 0 gives the entire path name unmodified.
o Setting -p 1 gives:
o Without the leading slash, -p 4 gives:
o Not specifying -p at all gives:
When using -b in some file system implementations, the sav-
ing of a .orig file may produce unwanted results. In the
case of 12-, 13-, or 14-character file names, on file sys-
tems supporting 14-character maximum file names, the .orig
file will overwrite the new file.
See environ(5) for descriptions of the following environment
variables that affect the execution of patch: LANG, LC_ALL,
LC_CTYPE, LC_MESSAGES, LC_TIME, and NLSPATH.
The output of patch the save files (.orig suffixes) and the
reject files (.rej suffixes) will be text files.
A patch file may contain patching instructions for more than
one file. File names are determined as specified in Patch
Determination. When the -b option is specified, for each
patched file, the original will be saved in a file of the
same name with the suffix .orig appended to it.
For each patched file, a reject file may also be created as
noted in Patch Application. In the absence of an -r option,
the name of this file will be formed by appending the suffix
.rej to the original file name.
Patch File 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 file name identification in
the format produced by diff -c, and one or more sets of diff
output, which are customarily called hunks.
patch recognizes the following expression in the header
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, patch will
remove this sequence before proceeding. Within each patch,
if the type of difference is context, patch recognizes the
*** 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
File Name Determination
If no file operand is specified, patch performs the follow-
ing steps to obtain a path name:
1. If the patch contains the strings *** and ---, patch
strips components from the beginning of each path name
(depending on the presence or value of the -p option),
then tests for the existence of both files in the current
directory (or directory specified with the -d option).
2. If both files exist, patch assumes that no path name can
be obtained from this step. If the header information
contains a line with the string Index:, patch strips com-
ponents from the beginning of the path name (depending on
-p), then tests for the existence of this file in the
current directory (or directory specified with the -d
3. If an SCCS directory exists in the current directory,
patch will attempt to perform a get -e SCCS/s.filename
command to retrieve an editable version of the file.
4. If no path name can be obtained by applying the previous
steps, or if the path names obtained do not exist, patch
will write a prompt to standard output and request a file
name interactively from standard input.
If the -c, -e, -n, or -u option is present, patch will
interpret information within each hunk as a context differ-
ence, an ed difference, a normal difference, or a unified
context difference, respectively. In the absence of any of
these options, patch determines the type of difference based
on the format of information within the hunk.
For each hunk, patch begins to search for the place to apply
the patch at the line number at the beginning of the hunk,
plus or minus any offset used in applying the previous hunk.
If lines 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 will take place, ignoring the first and
last line of context. If that fails, the first two and last
two lines of context will be ignored and another scan will
be made. Implementations may search more extensively for
If no location can be found, patch will append the hunk to
the reject file. The rejected hunk will be written in
context-difference format regardless of the format of the
patch file. If the input was a normal or ed -style differ-
ence, the reject file may contain differences with zero
lines of context. The line numbers on the hunks in the
reject file may be different from the line numbers in the
patch file since they will reflect the approximate locations
for the failed hunks in the new file rather than the old
If the type of patch is an ed diff, the implementation may
accomplish the patching by invoking the ed command.
The following exit values are returned:
0 Successful completion.
1 One or more lines were written to a reject file.
>1 An error occurred.
See attributes(5) for descriptions of the following attri-
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| Availability | SUNWcsu |
| Interface Stability | Standard |
ed(1), diff(1), attributes(5), environ(5), standards(5)
Man(1) output converted with