path: root/man1p/patch.1p

.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved 
.TH "PATCH" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\" patch 
.SH NAME
patch \- apply changes to files
.SH SYNOPSIS
.LP
\fBpatch\fP \fB[\fP\fB-blNR\fP\fB][\fP \fB-c| -e| -n\fP\fB][\fP\fB-d\fP
\fIdir\fP\fB][\fP\fB-D\fP \fIdefine\fP\fB][\fP\fB-i\fP \fIpatchfile\fP\fB]
.br
\fP \fB\ \ \ \ \ \ \fP \fB[\fP\fB-o\fP \fIoutfile\fP\fB][\fP\fB-p\fP
\fInum\fP\fB][\fP\fB-r\fP \fIrejectfile\fP\fB][\fP\fIfile\fP\fB]\fP\fB\fP
.SH DESCRIPTION
.LP
The \fIpatch\fP utility shall read a source (patch) file containing
any of the three forms of difference (diff) listings
produced by the \fIdiff\fP utility (normal, context, or in the style
of \fIed\fP) and apply those differences to a file. By default, \fIpatch\fP
shall read from the standard
input.
.LP
The \fIpatch\fP utility shall attempt to determine the type of the
\fIdiff\fP listing,
unless overruled by a \fB-c\fP, \fB-e\fP, or \fB-n\fP option.
.LP
If the patch file contains more than one patch, \fIpatch\fP shall
attempt to apply each of them as if they came from separate
patch files. (In this case, the application shall ensure that the
name of the patch file is determinable for each \fIdiff\fP listing.)
.SH OPTIONS
.LP
The \fIpatch\fP utility shall conform to the Base Definitions volume
of IEEE\ Std\ 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
.LP
The following options shall be supported:
.TP 7
\fB-b\fP
Save 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 \fB.orig\fP appended to it. If the file already exists,
it shall be overwritten; if multiple patches are applied to the
same file, the \fB.orig\fP file shall be written only for the first
patch. When the \fB-o\fP \fIoutfile\fP option is also
specified, \fIfile\fP \fB.orig\fP shall not be created but, if \fIoutfile\fP
already exists, \fIoutfile\fP \fB.orig\fP shall
be created.
.TP 7
\fB-c\fP
Interpret the patch file as a context difference (the output of the
utility \fIdiff\fP
when the \fB-c\fP or \fB-C\fP options are specified).
.TP 7
\fB-d\ \fP \fIdir\fP
Change the current directory to \fIdir\fP before processing as described
in the EXTENDED DESCRIPTION section.
.TP 7
\fB-D\ \fP \fIdefine\fP
Mark changes with one of the following C preprocessor constructs:
.sp
.RS
.nf

\fB#ifdef define
\&...
#endif
.sp

#ifndef define
\&...
#endif
\fP
.fi
.RE
.LP
optionally combined with the C preprocessor construct \fB#else\fP.
If the patched file is processed with the C preprocessor,
where the macro \fIdefine\fP is defined, the output shall contain
the changes from the patch file; otherwise, the output shall not
contain the patches specified in the patch file.
.TP 7
\fB-e\fP
Interpret the patch file as an \fIed\fP script, rather than a \fIdiff\fP
script.
.TP 7
\fB-i\ \fP \fIpatchfile\fP
Read the patch information from the file named by the pathname \fIpatchfile\fP,
rather than the standard input.
.TP 7
\fB-l\fP
(The letter ell.) Cause any sequence of <blank>s in the difference
script to match any sequence of <blank>s in the
input file. Other characters shall be matched exactly.
.TP 7
\fB-n\fP
Interpret the script as a normal difference.
.TP 7
\fB-N\fP
Ignore patches where the differences have already been applied to
the file; by default, already-applied patches shall be
rejected.
.TP 7
\fB-o\ \fP \fIoutfile\fP
Instead of modifying the files (specified by the \fIfile\fP operand
or the difference listings) directly, write a copy of the
file referenced by each patch, with the appropriate differences applied,
to \fIoutfile\fP. Multiple patches for a single file
shall be applied to the intermediate versions of the file created
by any previous patches, and shall result in multiple,
concatenated versions of the file being written to \fIoutfile\fP.
.TP 7
\fB-p\ \fP \fInum\fP
For all pathnames in the patch file that indicate the names of files
to be patched, delete \fInum\fP pathname components from
the beginning of each pathname. If the pathname in the patch file
is absolute, any leading slashes shall be considered the first
component (that is, \fB-p\ 1\fP shall remove the leading slashes).
Specifying \fB-p\ 0\fP shall cause the full pathname
to be used. If \fB-p\fP is not specified, only the basename (the final
pathname component) shall be used.
.TP 7
\fB-R\fP
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 \fB-R\fP option cannot be used with \fIed\fP scripts.
The \fIpatch\fP utility
shall attempt to reverse each portion of the script before applying
it. Rejected differences shall be saved in swapped format. If
this option is not specified, and until a portion of the patch file
is successfully applied, \fIpatch\fP attempts to apply each
portion in its reversed sense as well as in its normal sense. If the
attempt is successful, the user shall be prompted to determine
whether the \fB-R\fP option should be set.
.TP 7
\fB-r\ \fP \fIrejectfile\fP
Override the default reject filename. In the default case, the reject
file shall have the same name as the output file, with
the suffix \fB.rej\fP appended to it; see Patch Application .
.sp
.SH OPERANDS
.LP
The following operand shall be supported:
.TP 7
\fIfile\fP
A pathname of a file to patch.
.sp
.SH STDIN
.LP
See the INPUT FILES section.
.SH INPUT FILES
.LP
Input files shall be text files.
.SH ENVIRONMENT VARIABLES
.LP
The following environment variables shall affect the execution of
\fIpatch\fP:
.TP 7
\fILANG\fP
Provide a default value for the internationalization variables that
are unset or null. (See the Base Definitions volume of
IEEE\ Std\ 1003.1-2001, Section 8.2, Internationalization Variables
for
the precedence of internationalization variables used to determine
the values of locale categories.)
.TP 7
\fILC_ALL\fP
If set to a non-empty string value, override the values of all the
other internationalization variables.
.TP 7
\fILC_CTYPE\fP
Determine the locale for the interpretation of sequences of bytes
of text data as characters (for example, single-byte as
opposed to multi-byte characters in arguments and input files).
.TP 7
\fILC_MESSAGES\fP
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.
.TP 7
\fINLSPATH\fP
Determine the location of message catalogs for the processing of \fILC_MESSAGES
\&.\fP 
.TP 7
\fILC_TIME\fP
Determine the locale for recognizing the format of file timestamps
written by the \fIdiff\fP utility in a context-difference input file.
.sp
.SH ASYNCHRONOUS EVENTS
.LP
Default.
.SH STDOUT
.LP
Not used.
.SH STDERR
.LP
The standard error shall be used for diagnostic and informational
messages.
.SH OUTPUT FILES
.LP
The output of the \fIpatch\fP utility, the save files ( \fB.orig\fP
suffixes), and the reject files ( \fB.rej\fP suffixes)
shall be text files.
.SH EXTENDED DESCRIPTION
.LP
A patch file may contain patching instructions for more than one file;
filenames shall be determined as specified in Filename Determination
\&. When the \fB-b\fP option is specified, for each patched file, the
original shall
be saved in a file of the same name with the suffix \fB.orig\fP appended
to it.
.LP
For each patched file, a reject file may also be created as noted
in Patch Application . In the
absence of a \fB-r\fP option, the name of this file shall be formed
by appending the suffix \fB.rej\fP to the original
filename.
.SS Patch File Format
.LP
The patch file shall contain zero or more lines of header information
followed by one or more patches. Each patch shall contain
zero or more lines of filename identification in the format produced
by \fIdiff\fP \fB-c\fP,
and one or more sets of \fIdiff\fP output, which are customarily called
\fIhunks\fP.
.LP
The \fIpatch\fP utility shall recognize the following expression in
the header information:
.TP 7
\fBIndex:\ \fP \fIpathname\fP
.sp
The file to be patched is named \fIpathname\fP.
.sp
.LP
If all lines (including headers) within a patch begin with the same
leading sequence of <blank>s, the \fIpatch\fP utility
shall remove this sequence before proceeding. Within each patch, if
the type of difference is context, the \fIpatch\fP utility
shall recognize the following expressions:
.TP 7
***\ \fIfilename\ timestamp\fP
.sp
The patches arose from \fIfilename\fP.
.TP 7
---\ \fIfilename\ timestamp\fP
.sp
The patches should be applied to \fIfilename\fP.
.sp
.LP
Each hunk within a patch shall be the \fIdiff\fP output to change
a line range within the
original file. The line numbers for successive hunks within a patch
shall occur in ascending order.
.SS Filename Determination
.LP
If no \fIfile\fP operand is specified, \fIpatch\fP shall perform the
following steps to determine the filename to use:
.IP " 1." 4
If the type of \fIdiff\fP is context, the \fIpatch\fP utility shall
delete pathname
components (as specified by the \fB-p\fP option) from the filename
on the line beginning with \fB"***"\fP , then test for the
existence of this file relative to the current directory (or the directory
specified with the \fB-d\fP option). If the file
exists, the \fIpatch\fP utility shall use this filename.
.LP
.IP " 2." 4
If the type of \fIdiff\fP is context, the \fIpatch\fP utility shall
delete the pathname
components (as specified by the \fB-p\fP option) from the filename
on the line beginning with \fB"---"\fP , then test for the
existence of this file relative to the current directory (or the directory
specified with the \fB-d\fP option). If the file
exists, the \fIpatch\fP utility shall use this filename.
.LP
.IP " 3." 4
If the header information contains a line beginning with the string
\fBIndex:\fP, the \fIpatch\fP utility shall delete
pathname components (as specified by the \fB-p\fP option) from this
line, then test for the existence of this file relative to the
current directory (or the directory specified with the \fB-d\fP option).
If the file exists, the \fIpatch\fP utility shall use
this filename.
.LP
.IP " 4." 4
If an \fBSCCS\fP directory exists in the current directory, \fIpatch\fP
shall attempt to perform a \fIget\fP \fB-e\fP \fBSCCS/s.\fP \fIfilename\fP
command to retrieve an editable version of the
file. If the file exists, the \fIpatch\fP utility shall use this filename.
.LP
.IP " 5." 4
The \fIpatch\fP utility shall write a prompt to standard output and
request a filename interactively from the controlling
terminal (for example, \fB/dev/tty\fP).
.LP
.SS Patch Application
.LP
If the \fB-c\fP, \fB-e\fP, or \fB-n\fP option is present, the \fIpatch\fP
utility shall interpret information within each
hunk as a context difference, an \fIed\fP difference, or a normal
difference, respectively. In
the absence of any of these options, the \fIpatch\fP utility shall
determine the type of difference based on the format of
information within the hunk.
.LP
For each hunk, the \fIpatch\fP utility shall begin 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, \fIpatch\fP shall scan both forwards and backwards at least
1000 bytes for a set of lines that match the hunk context.
.LP
If no such place is found and it is a context difference, then another
scan shall take place, ignoring the first and last line
of context. If that fails, the first two and last two lines of context
shall be ignored and another scan shall be made.
Implementations may search more extensively for installation locations.
.LP
If no location can be found, the \fIpatch\fP utility shall append
the hunk to the reject file. The rejected hunk shall be
written in context-difference format regardless of the format of the
patch file. If the input was a normal or \fIed\fP-style difference,
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 shall reflect the
approximate locations for the failed hunks in the new file rather
than the old one.
.LP
If the type of patch is an \fIed\fP diff, the implementation may accomplish
the patching by
invoking the \fIed\fP utility.
.SH EXIT STATUS
.LP
The following exit values shall be returned:
.TP 7
\ 0
Successful completion.
.TP 7
\ 1
One or more lines were written to a reject file.
.TP 7
>1
An error occurred.
.sp
.SH CONSEQUENCES OF ERRORS
.LP
Patches that cannot be correctly placed in the file shall be written
to a reject file.
.LP
\fIThe following sections are informative.\fP
.SH APPLICATION USAGE
.LP
The \fB-R\fP option does not work with \fIed\fP scripts because there
is too little
information to reconstruct the reverse operation.
.LP
The \fB-p\fP option makes it possible to customize a patch file to
local user directory structures without manually editing the
patch file. For example, if the filename in the patch file was:
.sp
.RS
.nf

\fB/curds/whey/src/blurfl/blurfl.c
\fP
.fi
.RE
.LP
Setting \fB-p\ 0\fP gives the entire pathname unmodified; \fB-p\ 1\fP
gives:
.sp
.RS
.nf

\fBcurds/whey/src/blurfl/blurfl.c
\fP
.fi
.RE
.LP
without the leading slash, \fB-p\ 4\fP gives:
.sp
.RS
.nf

\fBblurfl/blurfl.c
\fP
.fi
.RE
.LP
and not specifying \fB-p\fP at all gives:
.sp
.RS
.nf

\fBblurfl.c .
\fP
.fi
.RE
.SH EXAMPLES
.LP
None.
.SH RATIONALE
.LP
Some of the functionality in historical \fIpatch\fP implementations
was not specified. The following documents those features
present in historical implementations that have not been specified.
.LP
A deleted piece of functionality was the \fB'+'\fP pseudo-option allowing
an additional set of options and a patch file
operand to be given. This was seen as being insufficiently useful
to standardize.
.LP
In historical implementations, if the string \fB"Prereq:"\fP appeared
in the header, the \fIpatch\fP utility would search
for the corresponding version information (the string specified in
the header, delimited by <blank>s or the beginning or end
of a line or the file) anywhere in the original file. This was deleted
as too simplistic and insufficiently trustworthy a mechanism
to standardize. For example, if:
.sp
.RS
.nf

\fBPrereq: 1.2
\fP
.fi
.RE
.LP
were in the header, the presence of a delimited 1.2 anywhere in the
file would satisfy the prerequisite.
.LP
The following options were dropped from historical implementations
of \fIpatch\fP as insufficiently useful to standardize:
.TP 7
\fB-b\fP
The \fB-b\fP option historically provided a method for changing the
name extension of the backup file from the default
\fB\&.orig\fP. This option has been modified and retained in this volume
of IEEE\ Std\ 1003.1-2001.
.TP 7
\fB-F\fP
The \fB-F\fP option specified the number of lines of a context diff
to ignore when searching for a place to install a
patch.
.TP 7
\fB-f\fP
The \fB-f\fP option historically caused \fIpatch\fP not to request
additional information from the user.
.TP 7
\fB-r\fP
The \fB-r\fP option historically provided a method of overriding the
extension of the reject file from the default
\fB\&.rej\fP.
.TP 7
\fB-s\fP
The \fB-s\fP option historically caused \fIpatch\fP to work silently
unless an error occurred.
.TP 7
\fB-x\fP
The \fB-x\fP option historically set internal debugging flags.
.sp
.LP
In some file system implementations, the saving of a \fB.orig\fP file
may produce unwanted results. In the case of 12, 13, or
14-character filenames (on file systems supporting 14-character maximum
filenames), the \fB.orig\fP file overwrites the new file.
The reject file may also exceed this filename limit. It was suggested,
due to some historical practice, that a tilde (
\fB'~'\fP ) suffix be used instead of \fB.orig\fP and some other character
instead of the \fB.rej\fP suffix. This was
rejected because it is not obvious to the user which file is which.
The suffixes \fB.orig\fP and \fB.rej\fP are clearer and more
understandable.
.LP
The \fB-b\fP option has the opposite sense in some historical implementations-do
not save the \fB.orig\fP file. The default
case here is not to save the files, making \fIpatch\fP behave more
consistently with the other standard utilities.
.LP
The \fB-w\fP option in early proposals was changed to \fB-l\fP to
match historical practice.
.LP
The \fB-N\fP option was included because without it, a non-interactive
application cannot reject previously applied patches.
For example, if a user is piping the output of \fIdiff\fP into the
\fIpatch\fP utility, and
the user only wants to patch a file to a newer version non-interactively,
the \fB-N\fP option is required.
.LP
Changes to the \fB-l\fP option description were proposed to allow
matching across <newline>s in addition to just
<blank>s. Since this is not historical practice, and since some ambiguities
could result, it is suggested that future
developments in this area utilize another option letter, such as \fB-L\fP.
.SH FUTURE DIRECTIONS
.LP
None.
.SH SEE ALSO
.LP
\fIed\fP , \fIdiff\fP
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .