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.1‐2008, 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.1‐2008, 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.1‐2008.

       −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.1‐2008, 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, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) 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.unix.org/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                 2013                           PATCH(1P)