Provided by: patch_2.5.9-5_i386 bug


       patch - apply a diff file to an original


       patch [options] [originalfile [patchfile]]

       but usually just

       patch -pnum <patchfile


       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 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

       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.)  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 ordinary context diff form regardless of the
       input patch’s form.  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

       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.


       -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  represent  the  nonexistent  file.   See  the -V or
          --version-control option for details about how backup file names are

          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.

          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
          Prefix  pref  to  a file name when generating its simple backup file
          name.  For example, with -B /junk/ the simple backup file  name  for
          src/patch/util.c is /junk/src/patch/util.c.

          Read  and write all files in binary mode, except for standard output
          and  /dev/tty.   This  option  has  no  effect  on  POSIX-conforming
          systems.   On systems like DOS where this option makes a difference,
          the patch should be generated by diff -a --binary.

       -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.

          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 if patch is conforming to POSIX, negative otherwise.

          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.

       -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.

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


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


          without the leading slash, -p4 gives


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

          Conform more strictly to the POSIX standard, as follows.

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

           · Do not remove files that are empty after patching.

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

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

           · Do not backup files when there is a mismatch.

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

                 Output names as-is.

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

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

          c      Quote names as for a C language string.

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

          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.

       -U  or  --unified-reject-files
          Produce unified reject files. The default is to produce context type
          reject files.

          Put all rejects into rejectfile instead of creating separate  reject
          files  for  all files that have rejects. The rejectfile will contain
          headers that identify which file each reject refers  to.  Note  that
          the  global  reject  file  is created even if --dry-run is specified
          (while  non-global  reject  files  will  only  be  created   without

       -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.)

       -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

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

          Output extra information about the work being done.

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

       -Y pref  or  --basename-prefix=pref
          Prefix  pref  to  the  basename  of  a file name when generating its
          simple 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  suffix as the simple backup suffix.  For example, with -z - the
          simple backup file name for src/patch/util.c  is  src/patch/util.c-.
          The  backup suffix may also be specified by the SIMPLE_BACKUP_SUFFIX
          environment variable, which is overridden by this option.

       -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.


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

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

          Default value of the --quoting-style option.

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

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

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


          temporary files

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


       diff(1), ed(1)

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


       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:  in your
       makefile), since the recipient should be able to regenerate the derived
       files  anyway.   If  you must send diffs of derived files, generate the
       diffs using UTC, have the recipients apply the patch  with  the  -Z  or
       --set-utc  option, and have them remove any unpatched files that depend
       on patched files (e.g. with make clean).

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


       Diagnostics generally indicate that patch  couldn’t  parse  your  patch

       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, 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


       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.  Until a suitable interactive interface is added,  you  should
       probably  do  a  context diff in these cases to see if the changes made
       sense.  Of course, compiling without errors is a pretty good indication
       that the patch worked, but not always.

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


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

        · In  traditional  patch,  the -p option’s operand was optional, and a
          bare -p was 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

        · 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

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

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

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

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

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

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


       Please report bugs via email to <>.

       patch  could  be  smarter  about  partial  matches, excessively deviant
       offsets and swapped code, but that would take an extra pass.

       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.


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


       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.