Provided by: patch_2.6.1-3_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, if lines end in CRLF, or if  a
       diff  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:

        +o 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.

        +o 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.

        +o 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:

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

        +o 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.

        +o 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.

        +o 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.  This option is needed  on  POSIX
          systems when applying patches generated on non-POSIX systems to non-
          POSIX files.   (On  POSIX  systems,  file  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 of
          context 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.  A fuzz factor greater than or equal to the  number  of
          lines  of  context  in  the  context diff, ordinarily 3, ignores all
          context.

       -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 or --merge=merge or --merge=diff3
          Merge  a  patch  file into the original files similar to diff3(1) or
          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
              |||||||
              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
          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.

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

           +o Do not remove files that are empty after patching.

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

           +o Require that all options precede the files in the command line.

           +o 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 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.

        +o 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.

        +o 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.

        +o 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.

        +o 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.

        +o 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.

        +o 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
       Grunbacher added support for merging.

                                      GNU                             PATCH(1)