PATCH(1)                             General Commands Manual                             PATCH(1)

       patch - apply a diff file to an original

       patch [options] [originalfile [patchfile]]

       but usually just

       patch -pnum >>>>>> lines.  A typical conflict will look like this:

              lines from the original file
              original lines from the patch
              new lines from the patch

          The optional argument of --merge determines the output format for conflicts: the  diff3
          format  shows  the ||||||| section with the original lines from the patch; in the merge
          format, this section is missing.  The merge format is the default.

          This option implies --forward and does not take the --fuzz=num option into account.

       -n  or  --normal
          Interpret the patch file as a normal diff.

       -N  or  --forward
          When a patch does not apply, patch usually checks if the patch looks like it  has  been
          reversed.  The --forward option prevents that.  See also -R.

       -o outfile  or  --output=outfile
          Send  output  to outfile instead of patching files in place.  Do not use this option if
          outfile is one of the files to be patched.  When outfile is -, send output to  standard
          output,  and  send  any  messages  that would usually go to standard output to standard

       -pnum  or  --strip=num
          Strip the smallest prefix containing num leading slashes from each file name  found  in
          the  patch  file.   A  sequence  of one or more adjacent slashes is counted as a single
          slash.  This controls how file names found in the patch file are treated, in  case  you
          keep  your  files in a different directory than the person who sent out the patch.  For
          example, supposing the file name in the patch file was


       setting -p0 gives the entire file name unmodified, -p1 gives


       without the leading slash, -p4 gives


       and not specifying -p at all just gives you blurfl.c.  Whatever you end up with is  looked
       for either in the current directory, or the directory specified by the -d option.

          Conform more strictly to the POSIX standard, as follows.

           · Take  the  first  existing  file from the list (old, new, index) when intuiting file
             names from diff headers.

           · Do not remove files that are empty after patching.

           · Do not ask whether to get files from RCS, ClearCase, Perforce, or SCCS.

           · Require that all options precede the files in the command line.

           · Do not backup files when there is a mismatch.

          Use style word to quote output names.  The word should be one of the following:

                 Output names as-is.

          shell  Quote names for the shell if they contain shell metacharacters  or  would  cause
                 ambiguous output.

                 Quote names for the shell, even if they would normally not require quoting.

          c      Quote names as for a C language string.

          escape Quote as with c except omit the surrounding double-quote characters.

          You  can  specify  the default value of the --quoting-style option with the environment
          variable QUOTING_STYLE.  If that environment variable is not set, the default value  is

       -r rejectfile  or  --reject-file=rejectfile
          Put  rejects  into  rejectfile instead of the default .rej file.  When rejectfile is -,
          discard rejects.

       -R  or  --reverse
          Assume that this patch was created with the old  and  new  files  swapped.   (Yes,  I'm
          afraid  that  does happen occasionally, human nature being what it is.)  patch attempts
          to swap each hunk around before applying it.  Rejects come out in the  swapped  format.
          The  -R  option does not work with ed diff scripts because there is too little informa‐
          tion to reconstruct the reverse operation.

          If the first hunk of a patch fails, patch reverses the hunk to see if it can be applied
          that  way.   If  it  can,  you  are asked if you want to have the -R option set.  If it
          can't, the patch continues to be applied normally.  (Note: this method cannot detect  a
          reversed  patch  if  it is a normal diff and if the first command is an append (i.e. it
          should have been a delete) since appends always succeed, due to the fact  that  a  null
          context matches anywhere.  Luckily, most patches add or change lines rather than delete
          them, so most reversed normal diffs begin with a delete, which  fails,  triggering  the

          Behave  as requested when trying to modify a read-only file: ignore the potential prob‐
          lem, warn about it (the default), or fail.

          Produce reject files in the specified format (either context or unified).  Without this
          option,  rejected  hunks come out in unified diff format if the input patch was of that
          format, otherwise in ordinary context diff form.

       -s  or  --silent  or  --quiet
          Work silently, unless an error occurs.

          When looking for input files, follow symbolic  links.   Replaces  the  symbolic  links,
          instead  of modifying the files the symbolic links point to.  Git-style patches to sym‐
          bolic links will no longer apply.  This option exists for backwards compatibility  with
          previous versions of patch; its use is discouraged.

       -t  or  --batch
          Suppress  questions  like  -f,  but make some different assumptions: skip patches whose
          headers do not contain file names (the same as -f); skip patches for which the file has
          the  wrong  version  for  the  Prereq:  line  in the patch; and assume that patches are
          reversed if they look like they are.

       -T  or  --set-time
          Set the modification and access times of patched files from time stamps given  in  con‐
          text  diff  headers.  Unless specified in the time stamps, assume that the context diff
          headers use local time.

          Use of this option with time stamps that do not include time zones is not  recommended,
          because  patches  using local time cannot easily be used by people in other time zones,
          and because local time stamps are ambiguous when local  clocks  move  backwards  during
          daylight-saving  time  adjustments.   Make sure that time stamps include time zones, or
          generate patches with UTC and use the -Z or --set-utc option instead.

       -u  or  --unified
          Interpret the patch file as a unified context diff.

       -v  or  --version
          Print out patch's revision header and patch level, and exit.

       -V method  or  --version-control=method
          Use method to determine backup file names.   The  method  can  also  be  given  by  the
          PATCH_VERSION_CONTROL  (or,  if  that's not set, the VERSION_CONTROL) environment vari‐
          able, which is overridden by this option.  The method does not  affect  whether  backup
          files are made; it affects only the names of any backup files that are made.

          The value of method is like the GNU Emacs `version-control' variable; patch also recog‐
          nizes synonyms that are more descriptive.  The valid  values  for  method  are  (unique
          abbreviations are accepted):

          existing  or  nil
             Make  numbered  backups  of  files that already have them, otherwise simple backups.
             This is the default.

          numbered  or  t
             Make numbered backups.  The numbered backup file name for F is F.~N~ where N is  the
             version number.

          simple  or  never
             Make  simple backups.  The -B or --prefix, -Y or --basename-prefix, and -z or --suf‐
             fix options specify the simple backup file name.   If  none  of  these  options  are
             given,  then  a  simple  backup  suffix  is  used;  it  is  the  value  of  the SIM‐
             PLE_BACKUP_SUFFIX environment variable if set, and is .orig otherwise.

          With numbered or simple backups, if the backup file name is too long, the backup suffix
          ~  is  used  instead; if even appending ~ would make the name too long, then ~ replaces
          the last character of the file name.

          Output extra information about the work being done.

       -x num  or  --debug=num
          Set internal debugging flags of interest only to patch patchers.

       -Y pref  or  --basename-prefix=pref
          Use the simple method to determine backup file names  (see  the  -V  method  or  --ver‐
          sion-control method option), and prefix pref to the basename of a file name when gener‐
          ating its backup file name.  For example, with -Y .del/ the simple backup file name for
          src/patch/util.c is src/patch/.del/util.c.

       -z suffix  or  --suffix=suffix
          Use  the  simple  method  to  determine  backup file names (see the -V method or --ver‐
          sion-control method option), and use suffix as the suffix.  For example, with -z -  the
          backup file name for src/patch/util.c is src/patch/util.c-.

       -Z  or  --set-utc
          Set  the  modification and access times of patched files from time stamps given in con‐
          text diff headers. Unless specified in the time stamps, assume that  the  context  diff
          headers  use  Coordinated Universal Time (UTC, often known as GMT).  Also see the -T or
          --set-time option.

          The -Z or --set-utc and -T or --set-time options normally refrain from setting a file's
          time  if the file's original time does not match the time given in the patch header, or
          if its contents do not match the patch exactly.  However, if the -f or  --force  option
          is given, the file time is set regardless.

          Due  to the limitations of diff output format, these options cannot update the times of
          files whose contents have not changed.  Also, if you  use  these  options,  you  should
          remove (e.g. with make clean) all files that depend on the patched files, so that later
          invocations of make do not get confused by the patched files' times.

          This specifies whether patch gets missing or read-only files from RCS, ClearCase,  Per‐
          force, or SCCS by default; see the -g or --get option.

          If  set, patch conforms more strictly to the POSIX standard by default: see the --posix

          Default value of the --quoting-style option.

          Extension to use for simple backup file names instead of .orig.

          Directory to put temporary files in; patch uses the first environment variable in  this
          list  that  is  set.   If none are set, the default is system-dependent; it is normally
          /tmp on Unix hosts.

          Selects version control style; see the -v or --version-control option.

          temporary files

          controlling terminal; used to get answers to questions asked of the user

       diff(1), ed(1), merge(1).

       Marshall T. Rose and Einar A. Stefferud,  Proposed  Standard  for  Message  Encapsulation,
       Internet RFC 934  (1985-01).

       There  are  several  things  you  should  bear  in mind if you are going to be sending out

       Create your patch systematically.  A good method is the command  diff -Naur old new  where
       old  and  new identify the old and new directories.  The names old and new should not con‐
       tain any slashes.  The diff command's headers should have dates  and  times  in  Universal
       Time  using  traditional Unix format, so that patch recipients can use the -Z or --set-utc
       option.  Here is an example command, using Bourne shell syntax:

              LC_ALL=C TZ=UTC0 diff -Naur gcc-2.7 gcc-2.8

       Tell your recipients how to apply the patch by telling them which directory to cd to,  and
       which  patch  options to use.  The option string -Np1 is recommended.  Test your procedure
       by pretending to be a recipient and applying your patch to a copy of the original files.

       You can save people a lot of grief by keeping a patchlevel.h  file  which  is  patched  to
       increment  the patch level as the first diff in the patch file you send out.  If you put a
       Prereq: line in with the patch, it won't let them apply patches out of order without  some

       You can create a file by sending out a diff that compares /dev/null or an empty file dated
       the Epoch (1970-01-01 00:00:00 UTC) to the file you want to create.  This  only  works  if
       the  file  you  want to create doesn't exist already in the target directory.  Conversely,
       you can remove a file by sending out a context diff that compares the file to  be  deleted
       with  an  empty file dated the Epoch.  The file will be removed unless patch is conforming
       to POSIX and the -E or --remove-empty-files option is not given.  An easy way to  generate
       patches that create and remove files is to use GNU diff's -N or --new-file option.

       If  the  recipient  is  supposed to use the -pN option, do not send output that looks like

              diff -Naur v2.0.29/prog/README prog/README
              --- v2.0.29/prog/README   Mon Mar 10 15:13:12 1997
              +++ prog/README   Mon Mar 17 14:58:22 1997

       because the two file names have different numbers of slashes, and  different  versions  of
       patch  interpret  the  file names differently.  To avoid confusion, send output that looks
       like this instead:

              diff -Naur v2.0.29/prog/README v2.0.30/prog/README
              --- v2.0.29/prog/README   Mon Mar 10 15:13:12 1997
              +++ v2.0.30/prog/README   Mon Mar 17 14:58:22 1997

       Avoid sending patches that compare backup file names like README.orig,  since  this  might
       confuse patch into patching a backup file instead of the real file.  Instead, send patches
       that compare the same base file  names  in  different  directories,  e.g.  old/README  and

       Take  care  not  to  send  out reversed patches, since it makes people wonder whether they
       already applied the patch.

       Try not to have your patch modify derived files (e.g. the file configure where there is  a
       line  configure:  configure.in  in  your  makefile), since the recipient should be able to
       regenerate the derived files anyway.  If you must send diffs of  derived  files,  generate
       the  diffs using UTC, have the recipients apply the patch with the -Z or --set-utc option,
       and have them remove  any  unpatched  files  that  depend  on  patched  files  (e.g.  with
       make clean).

       While  you may be able to get away with putting 582 diff listings into one file, it may be
       wiser to group related patches into separate files in case something goes haywire.

       Diagnostics generally indicate that patch couldn't parse your patch file.

       If the --verbose option is given, the message Hmm... indicates that there  is  unprocessed
       text  in the patch file and that patch is attempting to intuit whether there is a patch in
       that text and, if so, what kind of patch it is.

       patch's exit status is 0 if all hunks are applied successfully, 1 if some hunks cannot  be
       applied  or  there  were  merge  conflicts,  and 2 if there is more serious trouble.  When
       applying a set of patches in a loop it behooves you to check this exit status so you don't
       apply a later patch to a partially patched file.

       Context  diffs  cannot  reliably  represent the creation or deletion of empty files, empty
       directories, or special files such as symbolic links.  Nor can they represent  changes  to
       file  metadata like ownership, permissions, or whether one file is a hard link to another.
       If changes like these are also required, separate instructions (e.g. a  shell  script)  to
       accomplish them should accompany the patch.

       patch  cannot  tell  if  the line numbers are off in an ed script, and can detect bad line
       numbers in a normal diff only when it finds a change or deletion.  A  context  diff  using
       fuzz  factor  3 may have the same problem.  You should probably do a context diff in these
       cases to see if the changes made sense.  Of course, compiling without errors is  a  pretty
       good indication that the patch worked, but not always.

       patch  usually  produces  the  correct  results, even when it has to do a lot of guessing.
       However, the results are guaranteed to be correct  only  when  the  patch  is  applied  to
       exactly the same version of the file that the patch was generated from.

       The POSIX standard specifies behavior that differs from patch's traditional behavior.  You
       should be aware of these differences if you must interoperate with patch versions 2.1  and
       earlier, which do not conform to POSIX.

        · In  traditional  patch, the -p option's operand was optional, and a bare -p was equiva‐
          lent to -p0.  The -p option now requires an operand, and -p 0 is now equivalent to -p0.
          For maximum compatibility, use options like -p0 and -p1.

          Also,  traditional patch simply counted slashes when stripping path prefixes; patch now
          counts pathname components.  That is, a sequence of one or more  adjacent  slashes  now
          counts as a single slash.  For maximum portability, avoid sending patches containing //
          in file names.

        · In traditional patch, backups were enabled by default.  This behavior  is  now  enabled
          with the -b or --backup option.

          Conversely,  in POSIX patch, backups are never made, even when there is a mismatch.  In
          GNU patch, this behavior is enabled with the --no-backup-if-mismatch option, or by con‐
          forming  to POSIX with the --posix option or by setting the POSIXLY_CORRECT environment

          The -b suffix option of traditional patch is equivalent to the -b -z suffix options  of
          GNU patch.

        · Traditional patch used a complicated (and incompletely documented) method to intuit the
          name of the file to be patched from the patch header.  This method did not  conform  to
          POSIX,  and  had  a  few gotchas.  Now patch uses a different, equally complicated (but
          better documented) method that is optionally POSIX-conforming; we  hope  it  has  fewer
          gotchas.   The  two methods are compatible if the file names in the context diff header
          and the Index: line are all identical after prefix-stripping.  Your patch  is  normally
          compatible if each header's file names all contain the same number of slashes.

        · When  traditional  patch  asked  the  user a question, it sent the question to standard
          error and looked for an answer from the first file in the following  list  that  was  a
          terminal:  standard  error,  standard  output, /dev/tty, and standard input.  Now patch
          sends questions to standard output and gets answers from /dev/tty.  Defaults  for  some
          answers  have  been  changed  so that patch never goes into an infinite loop when using
          default answers.

        · Traditional patch exited with a status value that counted the number of bad  hunks,  or
          with  status  1 if there was real trouble.  Now patch exits with status 1 if some hunks
          failed, or with 2 if there was real trouble.

        · Limit yourself to the following options when sending instructions meant to be  executed
          by  anyone  running  GNU  patch,  traditional patch, or a patch that conforms to POSIX.
          Spaces are significant in the following list, and operands are required.

             -d dir
             -D define
             -o outfile
             -r rejectfile

       Please report bugs via email to .

       If code has been duplicated (for instance with #ifdef OLDCODE ... #else ... #endif), patch
       is  incapable  of  patching  both versions, and, if it works at all, will likely patch the
       wrong one, and tell you that it succeeded to boot.

       If you apply a patch you've already applied, patch thinks it  is  a  reversed  patch,  and
       offers to un-apply the patch.  This could be construed as a feature.

       Computing  how to merge a hunk is significantly harder than using the standard fuzzy algo‐
       rithm.  Bigger hunks, more context, a bigger offset from  the  original  location,  and  a
       worse match all slow the algorithm down.

       Copyright (C) 1984, 1985, 1986, 1988 Larry Wall.
       Copyright  (C)  1989,  1990,  1991,  1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
       2001, 2002, 2009 Free Software Foundation, Inc.

       Permission is granted to make and distribute verbatim copies of this manual  provided  the
       copyright notice and this permission notice are preserved on all copies.

       Permission  is  granted  to copy and distribute modified versions of this manual under the
       conditions for verbatim copying, provided that the entire resulting derived work  is  dis‐
       tributed under the terms of a permission notice identical to this one.

       Permission is granted to copy and distribute translations of this manual into another lan‐
       guage, under the above conditions for  modified  versions,  except  that  this  permission
       notice may be included in translations approved by the copyright holders instead of in the
       original English.

       Larry Wall wrote the original version of patch.  Paul  Eggert  removed  patch's  arbitrary
       limits;  added  support for binary files, setting file times, and deleting files; and made
       it conform better to POSIX.  Other contributors include Wayne Davison, who  added  unidiff
       support,  and  David  MacKenzie,  who  added  configuration  and  backup support.  Andreas
       Grünbacher added support for merging.

GNU                                                                                      PATCH(1)


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