patch(1p) — Linux manual page

PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

PATCH(1P)               POSIX Programmer's Manual              PATCH(1P)

PROLOG         top

       This manual page is part of the POSIX Programmer's Manual.  The
       Linux implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior),
       or the interface may not be implemented on Linux.

NAME         top

       patch — apply changes to files

SYNOPSIS         top

       patch [-blNR] [-c|-e|-n|-u] [-d dir] [-D define] [-i patchfile]
           [-o outfile] [-p num] [-r rejectfile] [file]

DESCRIPTION         top

       The patch utility shall read a source (patch) file containing any
       of four forms of difference (diff) listings produced by the diff
       utility (normal, copied context, unified context, or in the style
       of ed) and apply those differences to a file. By default, patch
       shall read from the standard input.

       The patch utility shall attempt to determine the type of the diff
       listing, unless overruled by a -c, -e, -n, or -u option.

       If the patch file contains more than one patch, patch 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 diff listing.)

OPTIONS         top

       The patch utility shall conform to the Base Definitions volume of
       POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.

       The following options shall be supported:

       -b        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 .orig appended to it. If
                 the file already exists, it shall be overwritten; if
                 multiple patches are applied to the same file, the
                 .orig file shall be written only for the first patch.
                 When the -o outfile option is also specified, file.orig
                 shall not be created but, if outfile already exists,
                 outfile.orig shall be created.

       -c        Interpret the patch file as a copied context difference
                 (the output of the utility diff when the -c or -C
                 options are specified).

       -d dir    Change the current directory to dir before processing
                 as described in the EXTENDED DESCRIPTION section.

       -D define Mark changes with one of the following C preprocessor
                 constructs:

                     #ifdef define
                     ...
                     #endif

                     #ifndef define
                     ...
                     #endif

                 optionally combined with the C preprocessor construct
                 #else.  If the patched file is processed with the C
                 preprocessor, where the macro define 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.

       -e        Interpret the patch file as an ed script, rather than a
                 diff script.

       -i patchfile
                 Read the patch information from the file named by the
                 pathname patchfile, rather than the standard input.

       -l        (The letter ell.) Cause any sequence of <blank>
                 characters in the difference script to match any
                 sequence of <blank> characters in the input file. Other
                 characters shall be 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 shall be rejected.

       -o outfile
                 Instead of modifying the files (specified by the file
                 operand or the difference listings) directly, write a
                 copy of the file referenced by each patch, with the
                 appropriate differences applied, to outfile.  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
                 outfile.

       -p num    For all pathnames in the patch file that indicate 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
                 <slash> characters shall be considered the first
                 component (that is, -p 1 shall remove the leading
                 <slash> characters). Specifying -p 0 shall cause the
                 full pathname to be used. If -p is not specified, only
                 the basename (the final pathname component) shall be
                 used.

       -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 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,
                 patch 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 -R option should be set.

       -r rejectfile
                 Override the default reject filename. In the default
                 case, the reject file shall have the same name as the
                 output file, with the suffix .rej appended to it; see
                 Patch Application.

       -u        Interpret the patch file as a unified context
                 difference (the output of the diff utility when the -u
                 or -U options are specified).

OPERANDS         top

       The following operand shall be supported:

       file      A pathname of a file to patch.

STDIN         top

       See the INPUT FILES section.

INPUT FILES         top

       Input files shall be text files.

ENVIRONMENT VARIABLES         top

       The following environment variables shall affect the execution of
       patch:

       LANG      Provide a default value for the internationalization
                 variables that are unset or null. (See the Base
                 Definitions volume of POSIX.1‐2017, Section 8.2,
                 Internationalization Variables the precedence of
                 internationalization variables used to determine the
                 values of locale categories.)

       LC_ALL    If set to a non-empty string value, override the values
                 of all the other internationalization variables.

       LC_COLLATE
                 Determine the locale for the behavior of ranges,
                 equivalence classes, and multi-character collating
                 elements used in the extended regular expression
                 defined for the yesexpr locale keyword in the
                 LC_MESSAGES category.

       LC_CTYPE  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), and the
                 behavior of character classes used in the extended
                 regular expression defined for the yesexpr locale
                 keyword in the LC_MESSAGES category.

       LC_MESSAGES
                 Determine the locale used to process affirmative
                 responses, and the locale used to affect the format and
                 contents of diagnostic messages and prompts written to
                 standard error.

       NLSPATH   Determine the location of message catalogs for the
                 processing of LC_MESSAGES.

       LC_TIME   Determine the locale for recognizing the format of file
                 timestamps written by the diff utility in a context-
                 difference input file.

ASYNCHRONOUS EVENTS         top

       Default.

STDOUT         top

       Not used.

STDERR         top

       The standard error shall be used for diagnostic and informational
       messages.

OUTPUT FILES         top

       The output of the patch utility, the save files (.orig suffixes),
       and the reject files (.rej suffixes) shall be text files.

EXTENDED DESCRIPTION         top

       A patch file may contain patching instructions for more than one
       file; filenames shall be determined as specified in Filename
       Determination.  When the -b option is specified, for each patched
       file, the original shall 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 a -r option, the name of
       this file shall be formed by appending the suffix .rej to the
       original filename.

   Patch File Format
       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 the -c, -C, -u, or -U options of the diff
       utility, and one or more sets of diff output, which are
       customarily called hunks.

       The patch utility shall recognize 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
       shall remove this sequence before proceeding. Within each patch,
       if the type of difference is common context, the patch utility
       shall recognize the following expressions:

       *** filename timestamp
             The patches arose from filename.

       --- filename timestamp
             The patches should be applied to filename.

       If the type of difference is unified context, the patch utility
       shall recognize the following expressions:

       --- filename timestamp
             The patches arose from filename.

       +++ filename timestamp
             The patches should be applied to filename.

       Each hunk within a patch shall be the diff output to change a
       line range within the original file. The line numbers for
       successive hunks within a patch shall occur in ascending order.

   Filename Determination
       If no file operand is specified, patch shall perform the
       following steps to determine the filename to use:

        1. If the type of diff is context, the patch utility shall
           delete pathname components (as specified by the -p option)
           from the filename on the line beginning with "***" (if copied
           context) or "---" (if unified context), then test for the
           existence of this file relative to the current directory (or
           the directory specified with the -d option). If the file
           exists, the patch utility shall use this filename.

        2. If the type of diff is context, the patch utility shall
           delete the pathname components (as specified by the -p
           option) from the filename on the line beginning with "---"
           (if copied context) or "+++" (if unified context), then test
           for the existence of this file relative to the current
           directory (or the directory specified with the -d option). If
           the file exists, the patch utility shall use this filename.

        3. If the header information contains a line beginning with the
           string Index:, the patch utility shall delete pathname
           components (as specified by the -p option) from this line,
           then test for the existence of this file relative to the
           current directory (or the directory specified with the -d
           option). If the file exists, the patch utility shall use this
           filename.

        4. If an SCCS directory exists in the current directory, patch
           shall attempt to perform a get -e SCCS/s.filename command to
           retrieve an editable version of the file. If the file exists,
           the patch utility shall use this filename.

        5. The patch utility shall write a prompt to standard output and
           request a filename interactively from the controlling
           terminal (for example, /dev/tty).

   Patch Application
       If the -c, -e, -n, or -u option is present, the patch utility
       shall interpret information within each hunk as a copied context
       difference, an ed difference, a normal difference, or a unified
       context difference, respectively. In the absence of any of these
       options, the patch utility shall determine the type of difference
       based on the format of information within the hunk.

       For each hunk, the patch 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, patch
       shall scan 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 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.

       If no location can be found, the patch utility shall append the
       hunk to the reject file. A rejected hunk that is a copied context
       difference, an ed difference, or a normal difference shall be
       written in copied-context-difference format regardless of the
       format of the patch file. It is implementation-defined whether a
       rejected hunk that is a unified context difference is written in
       copied-context-difference format or in unified-context-difference
       format.  If the input was a normal or ed-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.

       If the type of patch is an ed diff, the implementation may
       accomplish the patching by invoking the ed utility.

EXIT STATUS         top

       The following exit values shall be returned:

        0    Successful completion.

        1    One or more lines were written to a reject file.

       >1    An error occurred.

CONSEQUENCES OF ERRORS         top

       Patches that cannot be correctly placed in the file shall be
       written to a reject file.

       The following sections are informative.

APPLICATION USAGE         top

       The -R option does 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 filename in the patch file was:

           /curds/whey/src/blurfl/blurfl.c

       Setting -p 0 gives the entire pathname unmodified; -p 1 gives:

           curds/whey/src/blurfl/blurfl.c

       without the leading <slash>, -p 4 gives:

           blurfl/blurfl.c

       and not specifying -p at all gives:

           blurfl.c .

EXAMPLES         top

       None.

RATIONALE         top

       Some of the functionality in historical patch implementations was
       not specified. The following documents those features present in
       historical implementations that have not been specified.

       A deleted piece of functionality was the '+' 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.

       In historical implementations, if the string "Prereq:" appeared
       in the header, the patch utility would search for the
       corresponding version information (the string specified in the
       header, delimited by <blank> characters 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:

           Prereq: 1.2

       were in the header, the presence of a delimited 1.2 anywhere in
       the file would satisfy the prerequisite.

       The following options were dropped from historical
       implementations of patch as insufficiently useful to standardize:

       -b        The -b option historically provided a method for
                 changing the name extension of the backup file from the
                 default .orig.  This option has been modified and
                 retained in this volume of POSIX.1‐2017.

       -F        The -F option specified the number of lines of a
                 context diff to ignore when searching for a place to
                 install a patch.

       -f        The -f option historically caused patch not to request
                 additional information from the user.

       -r        The -r option historically provided a method of
                 overriding the extension of the reject file from the
                 default .rej.

       -s        The -s option historically caused patch to work
                 silently unless an error occurred.

       -x        The -x option historically set internal debugging
                 flags.

       In some file system implementations, the saving of a .orig file
       may 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. The
       reject file may also exceed this filename limit. It was
       suggested, due to some historical practice, that a <tilde> ('~')
       suffix be used instead of .orig and some other character instead
       of the .rej suffix. This was rejected because it is not obvious
       to the user which file is which. The suffixes .orig and .rej are
       clearer and more understandable.

       The -b option has the opposite sense in some historical
       implementations—do not save the .orig file. The default case here
       is not to save the files, making patch behave more consistently
       with the other standard utilities.

       The -w option in early proposals was changed to -l to match
       historical practice.

       The -N 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 diff into the patch
       utility, and the user only wants to patch a file to a newer
       version non-interactively, the -N option is required.

       Changes to the -l option description were proposed to allow
       matching across <newline> characters in addition to just <blank>
       characters. 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
       -L.

       The -u option of GNU patch has been added, along with support for
       unified context formats.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       diff(1p), ed(1p)

       The Base Definitions volume of POSIX.1‐2017, Chapter 8,
       Environment Variables, Section 12.2, Utility Syntax Guidelines

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 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 .

       Any typographical or formatting errors that appear in this page
       are most likely to have been introduced during the conversion of
       the source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group               2017                         PATCH(1P)