Provided by: patch_2.6-2ubuntu1_i386 bug

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 specified 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 normal 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 following:

          | 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.    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 heuristic 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  unnecessary,  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.

       --global-reject-file=rejectfile
          Same  as --reject-file=rejectfile.  This option is deprecated and is
          a Debian-specific  extension  that  will  be  removed  in  a  future
          release.

       -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.

       -U  or  --unified-reject-files
          Produce unified reject files.   This option is deprecated and  is  a
          Debian-specific  extension that will be removed in a future release.
          Use --reject-format=format instead.

       -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 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 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:  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

       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 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.

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 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 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-patch@gnu.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
       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)