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PATCH(1)                                                              PATCH(1)



NAME
       patch - apply a diff file to an original

SYNOPSIS
       patch [options] [originalfile [patchfile]]

       but usually just

       patch -pnum <patchfile

DESCRIPTION
       patch  takes  a  patch  file patchfile containing a difference listing produced by the diff program and applies
       those differences to one or more original files, producing patched versions.  Normally the patched versions are
       put  in place of the originals.  Backups can be made; see the -b or --backup option.  The names of the files to
       be patched are usually taken from the patch file, but if there's just one file to be patched it can  be  speci-
       fied on the command line as originalfile.

       Upon  startup,  patch attempts to determine the type of the diff listing, unless overruled by a -c (--context),
       -e (--ed), -n (--normal), or -u (--unified) option.  Context diffs (old-style, new-style, and unified) and nor-
       mal  diffs  are  applied  by  the patch program itself, while ed diffs are simply fed to the ed(1) editor via a
       pipe.

       patch tries to skip any leading garbage, apply the diff, and then skip any trailing garbage.   Thus  you  could
       feed  an  article  or  message  containing  a diff listing to patch, and it should work.  If the entire diff is
       indented by a consistent amount, or if a context diff contains lines ending in CRLF or is encapsulated  one  or
       more  times  by prepending "- " to lines starting with "-" as specified by Internet RFC 934, this is taken into
       account.  After removing indenting or encapsulation, lines beginning with # are ignored, as they are considered
       to be comments.

       With  context diffs, and to a lesser extent with normal diffs, patch can detect when the line numbers mentioned
       in the patch are incorrect, and attempts to find the correct place to apply each hunk of the patch.  As a first
       guess,  it takes the line number mentioned for the hunk, plus or minus any offset used in applying the previous
       hunk.  If that is not the correct place, patch scans both forwards and backwards for a set  of  lines  matching
       the context given in the hunk.  First patch looks for a place where all lines of the context match.  If no such
       place is found, and it's a context diff, and the maximum fuzz factor is set to 1 or  more,  then  another  scan
       takes  place ignoring the first and last line of context.  If that fails, and the maximum fuzz factor is set to
       2 or more, the first two and last two lines of context are ignored, and another scan  is  made.   (The  default
       maximum fuzz factor is 2.)

       Hunks with less prefix context than suffix context (after applying fuzz) must apply at the start of the file if
       their first line number is 1.  Hunks with more prefix context than suffix context (after  applying  fuzz)  must
       apply at the end of the file.

       If  patch  cannot  find a place to install that hunk of the patch, it puts the hunk out to a reject file, which
       normally is the name of the output file plus a .rej suffix, or # if .rej would generate a file name that is too
       long  (if  even  appending the single character # makes the file name too long, then # replaces the file name's
       last character).

       The rejected hunk comes out in unified or context diff format.  If the input was a normal  diff,  many  of  the
       contexts  are simply null.  The line numbers on the hunks in the reject file may be different than in the patch
       file: they reflect the approximate location patch thinks the failed hunks belong in the new  file  rather  than
       the old one.

       As  each  hunk  is  completed,  you  are  told if the hunk failed, and if so which line (in the new file) patch
       thought the hunk should go on.  If the hunk is installed at a different line from the line number specified  in
       the  diff,  you are told the offset.  A single large offset may indicate that a hunk was installed in the wrong
       place.  You are also told if a fuzz factor was used to make the  match,  in  which  case  you  should  also  be
       slightly suspicious.  If the --verbose option is given, you are also told about hunks that match exactly.

       If  no  original  file  origfile  is  specified on the command line, patch tries to figure out from the leading
       garbage what the name of the file to edit is, using the following rules.

       First, patch takes an ordered list of candidate file names as follows:

        ? If the header is that of a context diff, patch takes the old and new file names in the header.   A  name  is
          ignored  if  it does not have enough slashes to satisfy the -pnum or --strip=num option.  The name /dev/null
          is also ignored.

        ? If there is an Index: line in the leading garbage and if either the old and new names are both absent or  if
          patch is conforming to POSIX, patch takes the name in the Index: line.

        ? For  the  purpose  of  the following rules, the candidate file names are considered to be in the order (old,
          new, index), regardless of the order that they appear in the header.

       Then patch selects a file name from the candidate list as follows:

        ? If some of the named files exist, patch selects the first name if conforming to POSIX,  and  the  best  name
          otherwise.

        ? If  patch  is  not  ignoring RCS, ClearCase, Perforce, and SCCS (see the -g num or --get=num option), and no
          named files exist but an RCS, ClearCase, Perforce, or SCCS master is found, patch selects  the  first  named
          file with an RCS, ClearCase, Perforce, or SCCS master.

        ? If  no named files exist, no RCS, ClearCase, Perforce, or SCCS master was found, some names are given, patch
          is not conforming to POSIX, and the patch appears to create a file, patch selects the  best  name  requiring
          the creation of the fewest directories.

        ? If  no  file  name  results  from the above heuristics, you are asked for the name of the file to patch, and
          patch selects that name.

       To determine the best of a nonempty list of file names, patch first takes all the names with  the  fewest  path
       name  components; of those, it then takes all the names with the shortest basename; of those, it then takes all
       the shortest names; finally, it takes the first remaining name.

       Additionally, if the leading garbage contains a Prereq: line, patch takes the first word from the prerequisites
       line  (normally a version number) and checks the original file to see if that word can be found.  If not, patch
       asks for confirmation before proceeding.

       The upshot of all this is that you should be able to say, while in a news interface, something like the follow-
       ing:

          | patch -d /usr/src/local/blurfl

       and patch a file in the blurfl directory directly from the article containing the patch.

       If the patch file contains more than one patch, patch tries to apply each of them as if they came from separate
       patch files.  This means, among other things, that it is assumed that the name of the file  to  patch  must  be
       determined  for  each  diff  listing, and that the garbage before each diff listing contains interesting things
       such as file names and revision level, as mentioned previously.

OPTIONS
       -b  or  --backup
          Make backup files.  That is, when patching a file, rename or copy the original instead of removing it.  When
          backing  up a file that does not exist, an empty, unreadable backup file is created as a placeholder to rep-
          resent the nonexistent file.  See the -V or --version-control option for details about how backup file names
          are determined.

       --backup-if-mismatch
          Back  up  a  file  if  the patch does not match the file exactly and if backups are not otherwise requested.
          This is the default unless patch is conforming to POSIX.

       --no-backup-if-mismatch
          Do not back up a file if the patch does not match  the  file  exactly  and  if  backups  are  not  otherwise
          requested.  This is the default if patch is conforming to POSIX.

       -B pref  or  --prefix=pref
          Use the simple method to determine backup file names (see the -V method or --version-control method option),
          and append pref to a file name when generating its backup file name.  For example, with -B /junk/ the simple
          backup file name for src/patch/util.c is /junk/src/patch/util.c.

       --binary
          Write  all files in binary mode, except for standard output and /dev/tty.  When reading, disable the heuris-
          tic for transforming CRLF line endings into LF line endings.  (On POSIX-conforming systems, reads and writes
          never transform line endings. On Windows, reads and writes do transform line endings by default, and patches
          should be generated by diff --binary when line endings are significant.)

       -c  or  --context
          Interpret the patch file as a ordinary context diff.

       -d dir  or  --directory=dir
          Change to the directory dir immediately, before doing anything else.

       -D define  or  --ifdef=define
          Use the #ifdef ... #endif construct to mark changes, with define as the differentiating symbol.

       --dry-run
          Print the results of applying the patches without actually changing any files.

       -e  or  --ed
          Interpret the patch file as an ed script.

       -E  or  --remove-empty-files
          Remove output files that are empty after the patches have been applied.  Normally this  option  is  unneces-
          sary,  since  patch can examine the time stamps on the header to determine whether a file should exist after
          patching.  However, if the input is not a context diff or if patch is conforming to POSIX,  patch  does  not
          remove  empty  patched  files  unless  this option is given.  When patch removes a file, it also attempts to
          remove any empty ancestor directories.

       -f  or  --force
          Assume that the user knows exactly what he or she is doing, and do not  ask  any  questions.   Skip  patches
          whose  headers  do  not say which file is to be patched; patch files even though they have the wrong version
          for the Prereq: line in the patch; and assume that patches are not reversed even if they look like they are.
          This option does not suppress commentary; use -s for that.

       -F num  or  --fuzz=num
          Set  the  maximum  fuzz  factor.   This  option only applies to diffs that have context, and causes patch to
          ignore up to that many lines in looking for places to install a  hunk.   Note  that  a  larger  fuzz  factor
          increases  the odds of a faulty patch.  The default fuzz factor is 2, and it may not be set to more than the
          number of lines of context in the context diff, ordinarily 3.

       -g num  or  --get=num
          This option controls patch's actions when a file is under RCS or SCCS control, and  does  not  exist  or  is
          read-only  and  matches  the default version, or when a file is under ClearCase or Perforce control and does
          not exist.  If num is positive, patch gets (or checks out) the file from the  revision  control  system;  if
          zero,  patch  ignores  RCS,  ClearCase, Perforce, and SCCS and does not get the file; and if negative, patch
          asks the user whether to get the file.  The default value of this option  is  given  by  the  value  of  the
          PATCH_GET environment variable if it is set; if not, the default value is zero.

       --help
          Print a summary of options and exit.

       -i patchfile  or  --input=patchfile
          Read the patch from patchfile.  If patchfile is -, read from standard input, the default.

       -l  or  --ignore-whitespace
          Match  patterns loosely, in case tabs or spaces have been munged in your files.  Any sequence of one or more
          blanks in the patch file matches any sequence in the original file, and sequences of blanks at the  ends  of
          lines are ignored.  Normal characters must still match exactly.  Each line of the context must still match a
          line in the original file.

       --merge
          Merge a patch file into the original files similar to merge(1). If a conflict  is  found,  patch  outputs  a
          warning and brackets the conflict with <<<<<<< and >>>>>>> lines.  A typical conflict will look like this:

              <<<<<<<
              lines from the original file
              =======
              lines from the patch
              >>>>>>>

          If  there  are  conflicts,  the user should edit the result and delete one of the alternatives.  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
          Ignore patches that seem to be reversed or already applied.  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 error.

       -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

             /u/howard/src/blurfl/blurfl.c

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

             u/howard/src/blurfl/blurfl.c

          without the leading slash, -p4 gives

             blurfl/blurfl.c

          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.

       --posix
          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.

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

          literal
                 Output names as-is.

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

          shell-always
                 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 shell.

       -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 information 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 heuristic.)

       --reject-format=format
          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.

       -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  context  diff  headers,
          assuming  that  the  context  diff  headers use local time.  This option 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.  Instead of using this
          option, 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 variable, 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 recognizes 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 --suffix 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 SIMPLE_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.

       --verbose
          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 --version-control method option),
          and prefix pref to the basename of a file name when generating 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 --version-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 context diff headers,
          assuming 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.

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

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

       QUOTING_STYLE
          Default value of the --quoting-style option.

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

       TMPDIR, TMP, TEMP
          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.

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

FILES
       $TMPDIR/p*
          temporary files

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

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

       Marshall T. Rose and Einar A.  Stefferud,  Proposed  Standard  for  Message  Encapsulation,  Internet  RFC  934
       <URL:ftp://ftp.isi.edu/in-notes/rfc934.txt>; (1985-01).

NOTES FOR PATCH SENDERS
       There are several things you should bear in mind if you are going to be sending out patches.

       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 contain 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 apply-
       ing 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 warning.

       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 this:

          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 new/README.

       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: con-
       figure.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
       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.

CAVEATS
       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 with-
       out 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.

COMPATIBILITY ISSUES
       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 equivalent  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  com-
          ponents.   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 conforming  to  POSIX  with  the  --posix
          option or by setting the POSIXLY_CORRECT environment variable.

          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.

             -c
             -d dir
             -D define
             -e
             -l
             -n
             -N
             -o outfile
             -pnum
             -R
             -r rejectfile

BUGS
       Please report bugs via email to <bug-patchATgnu.org>.

       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 algorithm.  Bigger hunks,
       more context, a bigger offset from the original location, and a worse match all slow the algorithm down.

COPYING
       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 distributed under the terms of a permission notice
       identical to this one.

       Permission is granted to copy and distribute translations of this manual into another language, 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.

AUTHORS
       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 contribu-
       tors include Wayne Davison, who added unidiff support, and David MacKenzie, who added configuration and  backup
       support.  Andreas Grunbacher added support for merging.



                                      GNU                             PATCH(1)