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+This is diffutils.info-t, produced by makeinfo version 6.1 from
+diffutils.texi.
+
+This manual is for GNU Diffutils (version 3.5, 4 August 2016), and
+documents the GNU 'diff', 'diff3', 'sdiff', and 'cmp' commands for
+showing the differences between files and the GNU 'patch' command for
+using their output to update files.
+
+   Copyright (C) 1992-1994, 1998, 2001-2002, 2004, 2006, 2009-2016 Free
+Software Foundation, Inc.
+
+     Permission is granted to copy, distribute and/or modify this
+     document under the terms of the GNU Free Documentation License,
+     Version 1.3 or any later version published by the Free Software
+     Foundation; with no Invariant Sections, no Front-Cover Texts, and
+     no Back-Cover Texts.  A copy of the license is included in the
+     section entitled "GNU Free Documentation License."
+INFO-DIR-SECTION Individual utilities
+START-INFO-DIR-ENTRY
+* cmp: (diffutils)Invoking cmp.                 Compare 2 files byte by byte.
+* diff: (diffutils)Invoking diff.               Compare 2 files line by line.
+* diff3: (diffutils)Invoking diff3.             Compare 3 files line by line.
+* patch: (diffutils)Invoking patch.             Apply a patch to a file.
+* sdiff: (diffutils)Invoking sdiff.             Merge 2 files side-by-side.
+END-INFO-DIR-ENTRY
+
+INFO-DIR-SECTION Text creation and manipulation
+START-INFO-DIR-ENTRY
+* Diffutils: (diffutils).       Comparing and merging files.
+END-INFO-DIR-ENTRY
+
+
+File: diffutils.info-t,  Node: Top,  Next: Overview,  Up: (dir)
+
+Comparing and Merging Files
+***************************
+
+This manual is for GNU Diffutils (version 3.5, 4 August 2016), and
+documents the GNU 'diff', 'diff3', 'sdiff', and 'cmp' commands for
+showing the differences between files and the GNU 'patch' command for
+using their output to update files.
+
+   Copyright (C) 1992-1994, 1998, 2001-2002, 2004, 2006, 2009-2016 Free
+Software Foundation, Inc.
+
+     Permission is granted to copy, distribute and/or modify this
+     document under the terms of the GNU Free Documentation License,
+     Version 1.3 or any later version published by the Free Software
+     Foundation; with no Invariant Sections, no Front-Cover Texts, and
+     no Back-Cover Texts.  A copy of the license is included in the
+     section entitled "GNU Free Documentation License."
+
+* Menu:
+
+* Overview::              Preliminary information.
+* Comparison::            What file comparison means.
+
+* Output Formats::        Formats for two-way difference reports.
+* Incomplete Lines::      Lines that lack trailing newlines.
+* Comparing Directories:: Comparing files and directories.
+* Adjusting Output::      Making 'diff' output prettier.
+* diff Performance::      Making 'diff' smarter or faster.
+
+* Comparing Three Files:: Formats for three-way difference reports.
+* diff3 Merging::         Merging from a common ancestor.
+
+* Interactive Merging::   Interactive merging with 'sdiff'.
+
+* Merging with patch::    Using 'patch' to change old files into new ones.
+* Making Patches::        Tips for making and using patch distributions.
+
+* Invoking cmp::          Compare two files byte by byte.
+* Invoking diff::         Compare two files line by line.
+* Invoking diff3::        Compare three files line by line.
+* Invoking patch::        Apply a diff file to an original.
+* Invoking sdiff::        Side-by-side merge of file differences.
+
+* Standards conformance:: Conformance to the POSIX standard.
+* Projects::              If you've found a bug or other shortcoming.
+
+* Copying This Manual::   How to make copies of this manual.
+* Translations::          Available translations of this manual.
+* Index::                 Index.
+
+
+File: diffutils.info-t,  Node: Overview,  Next: Comparison,  Prev: Top,  Up: Top
+
+Overview
+********
+
+Computer users often find occasion to ask how two files differ.  Perhaps
+one file is a newer version of the other file.  Or maybe the two files
+started out as identical copies but were changed by different people.
+
+   You can use the 'diff' command to show differences between two files,
+or each corresponding file in two directories.  'diff' outputs
+differences between files line by line in any of several formats,
+selectable by command line options.  This set of differences is often
+called a "diff" or "patch".  For files that are identical, 'diff'
+normally produces no output; for binary (non-text) files, 'diff'
+normally reports only that they are different.
+
+   You can use the 'cmp' command to show the byte and line numbers where
+two files differ.  'cmp' can also show all the bytes that differ between
+the two files, side by side.  A way to compare two files character by
+character is the Emacs command 'M-x compare-windows'.  *Note Other
+Window: (emacs)Other Window, for more information on that command.
+
+   You can use the 'diff3' command to show differences among three
+files.  When two people have made independent changes to a common
+original, 'diff3' can report the differences between the original and
+the two changed versions, and can produce a merged file that contains
+both persons' changes together with warnings about conflicts.
+
+   You can use the 'sdiff' command to merge two files interactively.
+
+   You can use the set of differences produced by 'diff' to distribute
+updates to text files (such as program source code) to other people.
+This method is especially useful when the differences are small compared
+to the complete files.  Given 'diff' output, you can use the 'patch'
+program to update, or "patch", a copy of the file.  If you think of
+'diff' as subtracting one file from another to produce their difference,
+you can think of 'patch' as adding the difference to one file to
+reproduce the other.
+
+   This manual first concentrates on making diffs, and later shows how
+to use diffs to update files.
+
+   GNU 'diff' was written by Paul Eggert, Mike Haertel, David Hayes,
+Richard Stallman, and Len Tower.  Wayne Davison designed and implemented
+the unified output format.  The basic algorithm is described by Eugene
+W. Myers in "An O(ND) Difference Algorithm and its Variations",
+'Algorithmica' Vol. 1, 1986, pp. 251-266,
+<http://dx.doi.org/10.1007/BF01840446>; and in "A File Comparison
+Program", Webb Miller and Eugene W. Myers, 'Software--Practice and
+Experience' Vol. 15, 1985, pp. 1025-1040,
+<http://dx.doi.org/10.1002/spe.4380151102>.  The algorithm was
+independently discovered as described by Esko Ukkonen in "Algorithms for
+Approximate String Matching", 'Information and Control' Vol. 64, 1985,
+pp. 100-118, <http://dx.doi.org/10.1016/S0019-9958(85)80046-2>.  Related
+algorithms are surveyed by Alfred V. Aho in section 6.3 of "Algorithms
+for Finding Patterns in Strings", 'Handbook of Theoretical Computer
+Science' (Jan Van Leeuwen, ed.), Vol. A, 'Algorithms and Complexity',
+Elsevier/MIT Press, 1990, pp. 255-300.
+
+   GNU 'diff3' was written by Randy Smith.  GNU 'sdiff' was written by
+Thomas Lord.  GNU 'cmp' was written by Torbjo"rn Granlund and David
+MacKenzie.
+
+   GNU 'patch' was written mainly by Larry Wall and Paul Eggert; several
+GNU enhancements were contributed by Wayne Davison and David MacKenzie.
+Parts of this manual are adapted from a manual page written by Larry
+Wall, with his permission.
+
+
+File: diffutils.info-t,  Node: Comparison,  Next: Output Formats,  Prev: Overview,  Up: Top
+
+1 What Comparison Means
+***********************
+
+There are several ways to think about the differences between two files.
+One way to think of the differences is as a series of lines that were
+deleted from, inserted in, or changed in one file to produce the other
+file.  'diff' compares two files line by line, finds groups of lines
+that differ, and reports each group of differing lines.  It can report
+the differing lines in several formats, which have different purposes.
+
+   GNU 'diff' can show whether files are different without detailing the
+differences.  It also provides ways to suppress certain kinds of
+differences that are not important to you.  Most commonly, such
+differences are changes in the amount of white space between words or
+lines.  'diff' also provides ways to suppress differences in alphabetic
+case or in lines that match a regular expression that you provide.
+These options can accumulate; for example, you can ignore changes in
+both white space and alphabetic case.
+
+   Another way to think of the differences between two files is as a
+sequence of pairs of bytes that can be either identical or different.
+'cmp' reports the differences between two files byte by byte, instead of
+line by line.  As a result, it is often more useful than 'diff' for
+comparing binary files.  For text files, 'cmp' is useful mainly when you
+want to know only whether two files are identical, or whether one file
+is a prefix of the other.
+
+   To illustrate the effect that considering changes byte by byte can
+have compared with considering them line by line, think of what happens
+if a single newline character is added to the beginning of a file.  If
+that file is then compared with an otherwise identical file that lacks
+the newline at the beginning, 'diff' will report that a blank line has
+been added to the file, while 'cmp' will report that almost every byte
+of the two files differs.
+
+   'diff3' normally compares three input files line by line, finds
+groups of lines that differ, and reports each group of differing lines.
+Its output is designed to make it easy to inspect two different sets of
+changes to the same file.
+
+   These commands compare input files without necessarily reading them.
+For example, if 'diff' is asked simply to report whether two files
+differ, and it discovers that the files have different sizes, it need
+not read them to do its job.
+
+* Menu:
+
+* Hunks::             Groups of differing lines.
+* White Space::       Suppressing differences in white space.
+* Blank Lines::       Suppressing differences whose lines are all blank.
+* Specified Lines::   Suppressing differences whose lines all match a pattern.
+* Case Folding::      Suppressing differences in alphabetic case.
+* Brief::             Summarizing which files are different.
+* Binary::            Comparing binary files or forcing text comparisons.
+
+
+File: diffutils.info-t,  Node: Hunks,  Next: White Space,  Up: Comparison
+
+1.1 Hunks
+=========
+
+When comparing two files, 'diff' finds sequences of lines common to both
+files, interspersed with groups of differing lines called "hunks".
+Comparing two identical files yields one sequence of common lines and no
+hunks, because no lines differ.  Comparing two entirely different files
+yields no common lines and one large hunk that contains all lines of
+both files.  In general, there are many ways to match up lines between
+two given files.  'diff' tries to minimize the total hunk size by
+finding large sequences of common lines interspersed with small hunks of
+differing lines.
+
+   For example, suppose the file 'F' contains the three lines 'a', 'b',
+'c', and the file 'G' contains the same three lines in reverse order
+'c', 'b', 'a'.  If 'diff' finds the line 'c' as common, then the command
+'diff F G' produces this output:
+
+     1,2d0
+     < a
+     < b
+     3a2,3
+     > b
+     > a
+
+But if 'diff' notices the common line 'b' instead, it produces this
+output:
+
+     1c1
+     < a
+     ---
+     > c
+     3c3
+     < c
+     ---
+     > a
+
+It is also possible to find 'a' as the common line.  'diff' does not
+always find an optimal matching between the files; it takes shortcuts to
+run faster.  But its output is usually close to the shortest possible.
+You can adjust this tradeoff with the '--minimal' ('-d') option (*note
+diff Performance::).
+
+
+File: diffutils.info-t,  Node: White Space,  Next: Blank Lines,  Prev: Hunks,  Up: Comparison
+
+1.2 Suppressing Differences in Blank and Tab Spacing
+====================================================
+
+The '--ignore-tab-expansion' ('-E') option ignores the distinction
+between tabs and spaces on input.  A tab is considered to be equivalent
+to the number of spaces to the next tab stop (*note Tabs::).
+
+   The '--ignore-trailing-space' ('-Z') option ignores white space at
+line end.
+
+   The '--ignore-space-change' ('-b') option is stronger than '-E' and
+'-Z' combined.  It ignores white space at line end, and considers all
+other sequences of one or more white space characters within a line to
+be equivalent.  With this option, 'diff' considers the following two
+lines to be equivalent, where '$' denotes the line end:
+
+     Here lyeth  muche rychnesse  in lytell space.   -- John Heywood$
+     Here lyeth muche rychnesse in lytell space. -- John Heywood   $
+
+   The '--ignore-all-space' ('-w') option is stronger still.  It ignores
+differences even if one line has white space where the other line has
+none.  "White space" characters include tab, vertical tab, form feed,
+carriage return, and space; some locales may define additional
+characters to be white space.  With this option, 'diff' considers the
+following two lines to be equivalent, where '$' denotes the line end and
+'^M' denotes a carriage return:
+
+     Here lyeth  muche  rychnesse in lytell space.--  John Heywood$
+       He relyeth much erychnes  seinly tells pace.  --John Heywood   ^M$
+
+   For many other programs newline is also a white space character, but
+'diff' is a line-oriented program and a newline character always ends a
+line.  Hence the '-w' or '--ignore-all-space' option does not ignore
+newline-related changes; it ignores only other white space changes.
+
+
+File: diffutils.info-t,  Node: Blank Lines,  Next: Specified Lines,  Prev: White Space,  Up: Comparison
+
+1.3 Suppressing Differences Whose Lines Are All Blank
+=====================================================
+
+The '--ignore-blank-lines' ('-B') option ignores changes that consist
+entirely of blank lines.  With this option, for example, a file
+containing
+     1.  A point is that which has no part.
+
+     2.  A line is breadthless length.
+     -- Euclid, The Elements, I
+is considered identical to a file containing
+     1.  A point is that which has no part.
+     2.  A line is breadthless length.
+
+
+     -- Euclid, The Elements, I
+
+   Normally this option affects only lines that are completely empty,
+but if you also specify an option that ignores trailing spaces, lines
+are also affected if they look empty but contain white space.  In other
+words, '-B' is equivalent to '-I '^$'' by default, but it is equivalent
+to '-I '^[[:space:]]*$'' if '-b', '-w' or '-Z' is also specified.
+
+
+File: diffutils.info-t,  Node: Specified Lines,  Next: Case Folding,  Prev: Blank Lines,  Up: Comparison
+
+1.4 Suppressing Differences Whose Lines All Match a Regular Expression
+======================================================================
+
+To ignore insertions and deletions of lines that match a 'grep'-style
+regular expression, use the '--ignore-matching-lines=REGEXP' ('-I
+REGEXP') option.  You should escape regular expressions that contain
+shell metacharacters to prevent the shell from expanding them.  For
+example, 'diff -I '^[[:digit:]]'' ignores all changes to lines beginning
+with a digit.
+
+   However, '-I' only ignores the insertion or deletion of lines that
+contain the regular expression if every changed line in the hunk--every
+insertion and every deletion--matches the regular expression.  In other
+words, for each nonignorable change, 'diff' prints the complete set of
+changes in its vicinity, including the ignorable ones.
+
+   You can specify more than one regular expression for lines to ignore
+by using more than one '-I' option.  'diff' tries to match each line
+against each regular expression.
+
+
+File: diffutils.info-t,  Node: Case Folding,  Next: Brief,  Prev: Specified Lines,  Up: Comparison
+
+1.5 Suppressing Case Differences
+================================
+
+GNU 'diff' can treat lower case letters as equivalent to their upper
+case counterparts, so that, for example, it considers 'Funky Stuff',
+'funky STUFF', and 'fUNKy stuFf' to all be the same.  To request this,
+use the '-i' or '--ignore-case' option.
+
+
+File: diffutils.info-t,  Node: Brief,  Next: Binary,  Prev: Case Folding,  Up: Comparison
+
+1.6 Summarizing Which Files Differ
+==================================
+
+When you only want to find out whether files are different, and you
+don't care what the differences are, you can use the summary output
+format.  In this format, instead of showing the differences between the
+files, 'diff' simply reports whether files differ.  The '--brief' ('-q')
+option selects this output format.
+
+   This format is especially useful when comparing the contents of two
+directories.  It is also much faster than doing the normal line by line
+comparisons, because 'diff' can stop analyzing the files as soon as it
+knows that there are any differences.
+
+   You can also get a brief indication of whether two files differ by
+using 'cmp'.  For files that are identical, 'cmp' produces no output.
+When the files differ, by default, 'cmp' outputs the byte and line
+number where the first difference occurs, or reports that one file is a
+prefix of the other.  You can use the '-s', '--quiet', or '--silent'
+option to suppress that information, so that 'cmp' produces no output
+and reports whether the files differ using only its exit status (*note
+Invoking cmp::).
+
+   Unlike 'diff', 'cmp' cannot compare directories; it can only compare
+two files.
+
+
+File: diffutils.info-t,  Node: Binary,  Prev: Brief,  Up: Comparison
+
+1.7 Binary Files and Forcing Text Comparisons
+=============================================
+
+If 'diff' thinks that either of the two files it is comparing is binary
+(a non-text file), it normally treats that pair of files much as if the
+summary output format had been selected (*note Brief::), and reports
+only that the binary files are different.  This is because line by line
+comparisons are usually not meaningful for binary files.  This does not
+count as trouble, even though the resulting output does not capture all
+the differences.
+
+   'diff' determines whether a file is text or binary by checking the
+first few bytes in the file; the exact number of bytes is system
+dependent, but it is typically several thousand.  If every byte in that
+part of the file is non-null, 'diff' considers the file to be text;
+otherwise it considers the file to be binary.
+
+   Sometimes you might want to force 'diff' to consider files to be
+text.  For example, you might be comparing text files that contain null
+characters; 'diff' would erroneously decide that those are non-text
+files.  Or you might be comparing documents that are in a format used by
+a word processing system that uses null characters to indicate special
+formatting.  You can force 'diff' to consider all files to be text
+files, and compare them line by line, by using the '--text' ('-a')
+option.  If the files you compare using this option do not in fact
+contain text, they will probably contain few newline characters, and the
+'diff' output will consist of hunks showing differences between long
+lines of whatever characters the files contain.
+
+   You can also force 'diff' to report only whether files differ (but
+not how).  Use the '--brief' ('-q') option for this.
+
+   In operating systems that distinguish between text and binary files,
+'diff' normally reads and writes all data as text.  Use the '--binary'
+option to force 'diff' to read and write binary data instead.  This
+option has no effect on a POSIX-compliant system like GNU or traditional
+Unix.  However, many personal computer operating systems represent the
+end of a line with a carriage return followed by a newline.  On such
+systems, 'diff' normally ignores these carriage returns on input and
+generates them at the end of each output line, but with the '--binary'
+option 'diff' treats each carriage return as just another input
+character, and does not generate a carriage return at the end of each
+output line.  This can be useful when dealing with non-text files that
+are meant to be interchanged with POSIX-compliant systems.
+
+   The '--strip-trailing-cr' causes 'diff' to treat input lines that end
+in carriage return followed by newline as if they end in plain newline.
+This can be useful when comparing text that is imperfectly imported from
+many personal computer operating systems.  This option affects how lines
+are read, which in turn affects how they are compared and output.
+
+   If you want to compare two files byte by byte, you can use the 'cmp'
+program with the '--verbose' ('-l') option to show the values of each
+differing byte in the two files.  With GNU 'cmp', you can also use the
+'-b' or '--print-bytes' option to show the ASCII representation of those
+bytes.  *Note Invoking cmp::, for more information.
+
+   If 'diff3' thinks that any of the files it is comparing is binary (a
+non-text file), it normally reports an error, because such comparisons
+are usually not useful.  'diff3' uses the same test as 'diff' to decide
+whether a file is binary.  As with 'diff', if the input files contain a
+few non-text bytes but otherwise are like text files, you can force
+'diff3' to consider all files to be text files and compare them line by
+line by using the '-a' or '--text' option.
+
+
+File: diffutils.info-t,  Node: Output Formats,  Next: Incomplete Lines,  Prev: Comparison,  Up: Top
+
+2 'diff' Output Formats
+***********************
+
+'diff' has several mutually exclusive options for output format.  The
+following sections describe each format, illustrating how 'diff' reports
+the differences between two sample input files.
+
+* Menu:
+
+* Sample diff Input:: Sample 'diff' input files for examples.
+* Context::           Showing differences with the surrounding text.
+* Side by Side::      Showing differences in two columns.
+* Normal::            Showing differences without surrounding text.
+* Scripts::           Generating scripts for other programs.
+* If-then-else::      Merging files with if-then-else.
+
+
+File: diffutils.info-t,  Node: Sample diff Input,  Next: Context,  Up: Output Formats
+
+2.1 Two Sample Input Files
+==========================
+
+Here are two sample files that we will use in numerous examples to
+illustrate the output of 'diff' and how various options can change it.
+
+   This is the file 'lao':
+
+     The Way that can be told of is not the eternal Way;
+     The name that can be named is not the eternal name.
+     The Nameless is the origin of Heaven and Earth;
+     The Named is the mother of all things.
+     Therefore let there always be non-being,
+       so we may see their subtlety,
+     And let there always be being,
+       so we may see their outcome.
+     The two are the same,
+     But after they are produced,
+       they have different names.
+
+   This is the file 'tzu':
+
+     The Nameless is the origin of Heaven and Earth;
+     The named is the mother of all things.
+
+     Therefore let there always be non-being,
+       so we may see their subtlety,
+     And let there always be being,
+       so we may see their outcome.
+     The two are the same,
+     But after they are produced,
+       they have different names.
+     They both may be called deep and profound.
+     Deeper and more profound,
+     The door of all subtleties!
+
+   In this example, the first hunk contains just the first two lines of
+'lao', the second hunk contains the fourth line of 'lao' opposing the
+second and third lines of 'tzu', and the last hunk contains just the
+last three lines of 'tzu'.
+
+
+File: diffutils.info-t,  Node: Context,  Next: Side by Side,  Prev: Sample diff Input,  Up: Output Formats
+
+2.2 Showing Differences in Their Context
+========================================
+
+Usually, when you are looking at the differences between files, you will
+also want to see the parts of the files near the lines that differ, to
+help you understand exactly what has changed.  These nearby parts of the
+files are called the "context".
+
+   GNU 'diff' provides two output formats that show context around the
+differing lines: "context format" and "unified format".  It can
+optionally show in which function or section of the file the differing
+lines are found.
+
+   If you are distributing new versions of files to other people in the
+form of 'diff' output, you should use one of the output formats that
+show context so that they can apply the diffs even if they have made
+small changes of their own to the files.  'patch' can apply the diffs in
+this case by searching in the files for the lines of context around the
+differing lines; if those lines are actually a few lines away from where
+the diff says they are, 'patch' can adjust the line numbers accordingly
+and still apply the diff correctly.  *Note Imperfect::, for more
+information on using 'patch' to apply imperfect diffs.
+
+* Menu:
+
+* Context Format::  An output format that shows surrounding lines.
+* Unified Format::  A more compact output format that shows context.
+* Sections::        Showing which sections of the files differences are in.
+* Alternate Names:: Showing alternate file names in context headers.
+
+
+File: diffutils.info-t,  Node: Context Format,  Next: Unified Format,  Up: Context
+
+2.2.1 Context Format
+--------------------
+
+The context output format shows several lines of context around the
+lines that differ.  It is the standard format for distributing updates
+to source code.
+
+   To select this output format, use the '--context[=LINES]' ('-C
+LINES') or '-c' option.  The argument LINES that some of these options
+take is the number of lines of context to show.  If you do not specify
+LINES, it defaults to three.  For proper operation, 'patch' typically
+needs at least two lines of context.
+
+* Menu:
+
+* Example Context::  Sample output in context format.
+* Less Context::     Another sample with less context.
+* Detailed Context:: A detailed description of the context output format.
+
+
+File: diffutils.info-t,  Node: Example Context,  Next: Less Context,  Up: Context Format
+
+2.2.1.1 An Example of Context Format
+....................................
+
+Here is the output of 'diff -c lao tzu' (*note Sample diff Input::, for
+the complete contents of the two files).  Notice that up to three lines
+that are not different are shown around each line that is different;
+they are the context lines.  Also notice that the first two hunks have
+run together, because their contents overlap.
+
+     *** lao	2002-02-21 23:30:39.942229878 -0800
+     --- tzu	2002-02-21 23:30:50.442260588 -0800
+     ***************
+     *** 1,7 ****
+     - The Way that can be told of is not the eternal Way;
+     - The name that can be named is not the eternal name.
+       The Nameless is the origin of Heaven and Earth;
+     ! The Named is the mother of all things.
+       Therefore let there always be non-being,
+         so we may see their subtlety,
+       And let there always be being,
+     --- 1,6 ----
+       The Nameless is the origin of Heaven and Earth;
+     ! The named is the mother of all things.
+     ! 
+       Therefore let there always be non-being,
+         so we may see their subtlety,
+       And let there always be being,
+     ***************
+     *** 9,11 ****
+     --- 8,13 ----
+       The two are the same,
+       But after they are produced,
+         they have different names.
+     + They both may be called deep and profound.
+     + Deeper and more profound,
+     + The door of all subtleties!
+
+
+File: diffutils.info-t,  Node: Less Context,  Next: Detailed Context,  Prev: Example Context,  Up: Context Format
+
+2.2.1.2 An Example of Context Format with Less Context
+......................................................
+
+Here is the output of 'diff -C 1 lao tzu' (*note Sample diff Input::,
+for the complete contents of the two files).  Notice that at most one
+context line is reported here.
+
+     *** lao	2002-02-21 23:30:39.942229878 -0800
+     --- tzu	2002-02-21 23:30:50.442260588 -0800
+     ***************
+     *** 1,5 ****
+     - The Way that can be told of is not the eternal Way;
+     - The name that can be named is not the eternal name.
+       The Nameless is the origin of Heaven and Earth;
+     ! The Named is the mother of all things.
+       Therefore let there always be non-being,
+     --- 1,4 ----
+       The Nameless is the origin of Heaven and Earth;
+     ! The named is the mother of all things.
+     ! 
+       Therefore let there always be non-being,
+     ***************
+     *** 11 ****
+     --- 10,13 ----
+         they have different names.
+     + They both may be called deep and profound.
+     + Deeper and more profound,
+     + The door of all subtleties!
+
+
+File: diffutils.info-t,  Node: Detailed Context,  Prev: Less Context,  Up: Context Format
+
+2.2.1.3 Detailed Description of Context Format
+..............................................
+
+The context output format starts with a two-line header, which looks
+like this:
+
+     *** FROM-FILE FROM-FILE-MODIFICATION-TIME
+     --- TO-FILE TO-FILE-MODIFICATION TIME
+
+The time stamp normally looks like '2002-02-21 23:30:39.942229878 -0800'
+to indicate the date, time with fractional seconds, and time zone in
+Internet RFC 2822 format (ftp://ftp.isi.edu/in-notes/rfc2822.txt).  (The
+fractional seconds are omitted on hosts that do not support fractional
+time stamps.)  However, a traditional time stamp like 'Thu Feb 21
+23:30:39 2002' is used if the 'LC_TIME' locale category is either 'C' or
+'POSIX'.
+
+   You can change the header's content with the '--label=LABEL' option;
+see *note Alternate Names::.
+
+   Next come one or more hunks of differences; each hunk shows one area
+where the files differ.  Context format hunks look like this:
+
+     ***************
+     *** FROM-FILE-LINE-NUMBERS ****
+       FROM-FILE-LINE
+       FROM-FILE-LINE...
+     --- TO-FILE-LINE-NUMBERS ----
+       TO-FILE-LINE
+       TO-FILE-LINE...
+
+   If a hunk contains two or more lines, its line numbers look like
+'START,END'.  Otherwise only its end line number appears.  An empty hunk
+is considered to end at the line that precedes the hunk.
+
+   The lines of context around the lines that differ start with two
+space characters.  The lines that differ between the two files start
+with one of the following indicator characters, followed by a space
+character:
+
+'!'
+     A line that is part of a group of one or more lines that changed
+     between the two files.  There is a corresponding group of lines
+     marked with '!' in the part of this hunk for the other file.
+
+'+'
+     An "inserted" line in the second file that corresponds to nothing
+     in the first file.
+
+'-'
+     A "deleted" line in the first file that corresponds to nothing in
+     the second file.
+
+   If all of the changes in a hunk are insertions, the lines of
+FROM-FILE are omitted.  If all of the changes are deletions, the lines
+of TO-FILE are omitted.
+
+
+File: diffutils.info-t,  Node: Unified Format,  Next: Sections,  Prev: Context Format,  Up: Context
+
+2.2.2 Unified Format
+--------------------
+
+The unified output format is a variation on the context format that is
+more compact because it omits redundant context lines.  To select this
+output format, use the '--unified[=LINES]' ('-U LINES'), or '-u' option.
+The argument LINES is the number of lines of context to show.  When it
+is not given, it defaults to three.
+
+   At present, only GNU 'diff' can produce this format and only GNU
+'patch' can automatically apply diffs in this format.  For proper
+operation, 'patch' typically needs at least three lines of context.
+
+* Menu:
+
+* Example Unified::  Sample output in unified format.
+* Detailed Unified:: A detailed description of unified format.
+
+
+File: diffutils.info-t,  Node: Example Unified,  Next: Detailed Unified,  Up: Unified Format
+
+2.2.2.1 An Example of Unified Format
+....................................
+
+Here is the output of the command 'diff -u lao tzu' (*note Sample diff
+Input::, for the complete contents of the two files):
+
+     --- lao	2002-02-21 23:30:39.942229878 -0800
+     +++ tzu	2002-02-21 23:30:50.442260588 -0800
+     @@ -1,7 +1,6 @@
+     -The Way that can be told of is not the eternal Way;
+     -The name that can be named is not the eternal name.
+      The Nameless is the origin of Heaven and Earth;
+     -The Named is the mother of all things.
+     +The named is the mother of all things.
+     +
+      Therefore let there always be non-being,
+        so we may see their subtlety,
+      And let there always be being,
+     @@ -9,3 +8,6 @@
+      The two are the same,
+      But after they are produced,
+        they have different names.
+     +They both may be called deep and profound.
+     +Deeper and more profound,
+     +The door of all subtleties!
+
+
+File: diffutils.info-t,  Node: Detailed Unified,  Prev: Example Unified,  Up: Unified Format
+
+2.2.2.2 Detailed Description of Unified Format
+..............................................
+
+The unified output format starts with a two-line header, which looks
+like this:
+
+     --- FROM-FILE FROM-FILE-MODIFICATION-TIME
+     +++ TO-FILE TO-FILE-MODIFICATION-TIME
+
+The time stamp looks like '2002-02-21 23:30:39.942229878 -0800' to
+indicate the date, time with fractional seconds, and time zone.  The
+fractional seconds are omitted on hosts that do not support fractional
+time stamps.
+
+   You can change the header's content with the '--label=LABEL' option.
+*Note Alternate Names::.
+
+   Next come one or more hunks of differences; each hunk shows one area
+where the files differ.  Unified format hunks look like this:
+
+     @@ FROM-FILE-LINE-NUMBERS TO-FILE-LINE-NUMBERS @@
+      LINE-FROM-EITHER-FILE
+      LINE-FROM-EITHER-FILE...
+
+   If a hunk contains just one line, only its start line number appears.
+Otherwise its line numbers look like 'START,COUNT'.  An empty hunk is
+considered to start at the line that follows the hunk.
+
+   If a hunk and its context contain two or more lines, its line numbers
+look like 'START,COUNT'.  Otherwise only its end line number appears.
+An empty hunk is considered to end at the line that precedes the hunk.
+
+   The lines common to both files begin with a space character.  The
+lines that actually differ between the two files have one of the
+following indicator characters in the left print column:
+
+'+'
+     A line was added here to the first file.
+
+'-'
+     A line was removed here from the first file.
+
+
+File: diffutils.info-t,  Node: Sections,  Next: Alternate Names,  Prev: Unified Format,  Up: Context
+
+2.2.3 Showing Which Sections Differences Are in
+-----------------------------------------------
+
+Sometimes you might want to know which part of the files each change
+falls in.  If the files are source code, this could mean which function
+was changed.  If the files are documents, it could mean which chapter or
+appendix was changed.  GNU 'diff' can show this by displaying the
+nearest section heading line that precedes the differing lines.  Which
+lines are "section headings" is determined by a regular expression.
+
+* Menu:
+
+* Specified Headings::  Showing headings that match regular expressions.
+* C Function Headings:: Showing headings of C functions.
+
+
+File: diffutils.info-t,  Node: Specified Headings,  Next: C Function Headings,  Up: Sections
+
+2.2.3.1 Showing Lines That Match Regular Expressions
+....................................................
+
+To show in which sections differences occur for files that are not
+source code for C or similar languages, use the
+'--show-function-line=REGEXP' ('-F REGEXP') option.  'diff' considers
+lines that match the 'grep'-style regular expression REGEXP to be the
+beginning of a section of the file.  Here are suggested regular
+expressions for some common languages:
+
+'^[[:alpha:]$_]'
+     C, C++, Prolog
+'^('
+     Lisp
+'^@node'
+     Texinfo
+
+   This option does not automatically select an output format; in order
+to use it, you must select the context format (*note Context Format::)
+or unified format (*note Unified Format::).  In other output formats it
+has no effect.
+
+   The '--show-function-line' ('-F') option finds the nearest unchanged
+line that precedes each hunk of differences and matches the given
+regular expression.  Then it adds that line to the end of the line of
+asterisks in the context format, or to the '@@' line in unified format.
+If no matching line exists, this option leaves the output for that hunk
+unchanged.  If that line is more than 40 characters long, it outputs
+only the first 40 characters.  You can specify more than one regular
+expression for such lines; 'diff' tries to match each line against each
+regular expression, starting with the last one given.  This means that
+you can use '-p' and '-F' together, if you wish.
+
+
+File: diffutils.info-t,  Node: C Function Headings,  Prev: Specified Headings,  Up: Sections
+
+2.2.3.2 Showing C Function Headings
+...................................
+
+To show in which functions differences occur for C and similar
+languages, you can use the '--show-c-function' ('-p') option.  This
+option automatically defaults to the context output format (*note
+Context Format::), with the default number of lines of context.  You can
+override that number with '-C LINES' elsewhere in the command line.  You
+can override both the format and the number with '-U LINES' elsewhere in
+the command line.
+
+   The '--show-c-function' ('-p') option is equivalent to '-F
+'^[[:alpha:]$_]'' if the unified format is specified, otherwise '-c -F
+'^[[:alpha:]$_]'' (*note Specified Headings::).  GNU 'diff' provides
+this option for the sake of convenience.
+
+
+File: diffutils.info-t,  Node: Alternate Names,  Prev: Sections,  Up: Context
+
+2.2.4 Showing Alternate File Names
+----------------------------------
+
+If you are comparing two files that have meaningless or uninformative
+names, you might want 'diff' to show alternate names in the header of
+the context and unified output formats.  To do this, use the
+'--label=LABEL' option.  The first time you give this option, its
+argument replaces the name and date of the first file in the header; the
+second time, its argument replaces the name and date of the second file.
+If you give this option more than twice, 'diff' reports an error.  The
+'--label' option does not affect the file names in the 'pr' header when
+the '-l' or '--paginate' option is used (*note Pagination::).
+
+   Here are the first two lines of the output from 'diff -C 2
+--label=original --label=modified lao tzu':
+
+     *** original
+     --- modified
+
+
+File: diffutils.info-t,  Node: Side by Side,  Next: Normal,  Prev: Context,  Up: Output Formats
+
+2.3 Showing Differences Side by Side
+====================================
+
+'diff' can produce a side by side difference listing of two files.  The
+files are listed in two columns with a gutter between them.  The gutter
+contains one of the following markers:
+
+white space
+     The corresponding lines are in common.  That is, either the lines
+     are identical, or the difference is ignored because of one of the
+     '--ignore' options (*note White Space::).
+
+'|'
+     The corresponding lines differ, and they are either both complete
+     or both incomplete.
+
+'<'
+     The files differ and only the first file contains the line.
+
+'>'
+     The files differ and only the second file contains the line.
+
+'('
+     Only the first file contains the line, but the difference is
+     ignored.
+
+')'
+     Only the second file contains the line, but the difference is
+     ignored.
+
+'\'
+     The corresponding lines differ, and only the first line is
+     incomplete.
+
+'/'
+     The corresponding lines differ, and only the second line is
+     incomplete.
+
+   Normally, an output line is incomplete if and only if the lines that
+it contains are incomplete.  *Note Incomplete Lines::.  However, when an
+output line represents two differing lines, one might be incomplete
+while the other is not.  In this case, the output line is complete, but
+its the gutter is marked '\' if the first line is incomplete, '/' if the
+second line is.
+
+   Side by side format is sometimes easiest to read, but it has
+limitations.  It generates much wider output than usual, and truncates
+lines that are too long to fit.  Also, it relies on lining up output
+more heavily than usual, so its output looks particularly bad if you use
+varying width fonts, nonstandard tab stops, or nonprinting characters.
+
+   You can use the 'sdiff' command to interactively merge side by side
+differences.  *Note Interactive Merging::, for more information on
+merging files.
+
+* Menu:
+
+* Side by Side Format::  Controlling side by side output format.
+* Example Side by Side:: Sample side by side output.
+
+
+File: diffutils.info-t,  Node: Side by Side Format,  Next: Example Side by Side,  Up: Side by Side
+
+2.3.1 Controlling Side by Side Format
+-------------------------------------
+
+The '--side-by-side' ('-y') option selects side by side format.  Because
+side by side output lines contain two input lines, the output is wider
+than usual: normally 130 print columns, which can fit onto a traditional
+printer line.  You can set the width of the output with the
+'--width=COLUMNS' ('-W COLUMNS') option.  The output is split into two
+halves of equal width, separated by a small gutter to mark differences;
+the right half is aligned to a tab stop so that tabs line up.  Input
+lines that are too long to fit in half of an output line are truncated
+for output.
+
+   The '--left-column' option prints only the left column of two common
+lines.  The '--suppress-common-lines' option suppresses common lines
+entirely.
+
+
+File: diffutils.info-t,  Node: Example Side by Side,  Prev: Side by Side Format,  Up: Side by Side
+
+2.3.2 An Example of Side by Side Format
+---------------------------------------
+
+Here is the output of the command 'diff -y -W 72 lao tzu' (*note Sample
+diff Input::, for the complete contents of the two files).
+
+     The Way that can be told of is n   <
+     The name that can be named is no   <
+     The Nameless is the origin of He        The Nameless is the origin of He
+     The Named is the mother of all t   |    The named is the mother of all t
+                                        >
+     Therefore let there always be no        Therefore let there always be no
+       so we may see their subtlety,           so we may see their subtlety,
+     And let there always be being,          And let there always be being,
+       so we may see their outcome.            so we may see their outcome.
+     The two are the same,                   The two are the same,
+     But after they are produced,            But after they are produced,
+       they have different names.              they have different names.
+                                        >    They both may be called deep and
+                                        >    Deeper and more profound,
+                                        >    The door of all subtleties!
+
+
+File: diffutils.info-t,  Node: Normal,  Next: Scripts,  Prev: Side by Side,  Up: Output Formats
+
+2.4 Showing Differences Without Context
+=======================================
+
+The "normal" 'diff' output format shows each hunk of differences without
+any surrounding context.  Sometimes such output is the clearest way to
+see how lines have changed, without the clutter of nearby unchanged
+lines (although you can get similar results with the context or unified
+formats by using 0 lines of context).  However, this format is no longer
+widely used for sending out patches; for that purpose, the context
+format (*note Context Format::) and the unified format (*note Unified
+Format::) are superior.  Normal format is the default for compatibility
+with older versions of 'diff' and the POSIX standard.  Use the
+'--normal' option to select this output format explicitly.
+
+* Menu:
+
+* Example Normal::  Sample output in the normal format.
+* Detailed Normal:: A detailed description of normal output format.
+
+
+File: diffutils.info-t,  Node: Example Normal,  Next: Detailed Normal,  Up: Normal
+
+2.4.1 An Example of Normal Format
+---------------------------------
+
+Here is the output of the command 'diff lao tzu' (*note Sample diff
+Input::, for the complete contents of the two files).  Notice that it
+shows only the lines that are different between the two files.
+
+     1,2d0
+     < The Way that can be told of is not the eternal Way;
+     < The name that can be named is not the eternal name.
+     4c2,3
+     < The Named is the mother of all things.
+     ---
+     > The named is the mother of all things.
+     > 
+     11a11,13
+     > They both may be called deep and profound.
+     > Deeper and more profound,
+     > The door of all subtleties!
+
+
+File: diffutils.info-t,  Node: Detailed Normal,  Prev: Example Normal,  Up: Normal
+
+2.4.2 Detailed Description of Normal Format
+-------------------------------------------
+
+The normal output format consists of one or more hunks of differences;
+each hunk shows one area where the files differ.  Normal format hunks
+look like this:
+
+     CHANGE-COMMAND
+     < FROM-FILE-LINE
+     < FROM-FILE-LINE...
+     ---
+     > TO-FILE-LINE
+     > TO-FILE-LINE...
+
+   There are three types of change commands.  Each consists of a line
+number or comma-separated range of lines in the first file, a single
+character indicating the kind of change to make, and a line number or
+comma-separated range of lines in the second file.  All line numbers are
+the original line numbers in each file.  The types of change commands
+are:
+
+'LaR'
+     Add the lines in range R of the second file after line L of the
+     first file.  For example, '8a12,15' means append lines 12-15 of
+     file 2 after line 8 of file 1; or, if changing file 2 into file 1,
+     delete lines 12-15 of file 2.
+
+'FcT'
+     Replace the lines in range F of the first file with lines in range
+     T of the second file.  This is like a combined add and delete, but
+     more compact.  For example, '5,7c8,10' means change lines 5-7 of
+     file 1 to read as lines 8-10 of file 2; or, if changing file 2 into
+     file 1, change lines 8-10 of file 2 to read as lines 5-7 of file 1.
+
+'RdL'
+     Delete the lines in range R from the first file; line L is where
+     they would have appeared in the second file had they not been
+     deleted.  For example, '5,7d3' means delete lines 5-7 of file 1;
+     or, if changing file 2 into file 1, append lines 5-7 of file 1
+     after line 3 of file 2.
+
+
+File: diffutils.info-t,  Node: Scripts,  Next: If-then-else,  Prev: Normal,  Up: Output Formats
+
+2.5 Making Edit Scripts
+=======================
+
+Several output modes produce command scripts for editing FROM-FILE to
+produce TO-FILE.
+
+* Menu:
+
+* ed Scripts:: Using 'diff' to produce commands for 'ed'.
+* Forward ed:: Making forward 'ed' scripts.
+* RCS::        A special 'diff' output format used by RCS.
+
+
+File: diffutils.info-t,  Node: ed Scripts,  Next: Forward ed,  Up: Scripts
+
+2.5.1 'ed' Scripts
+------------------
+
+'diff' can produce commands that direct the 'ed' text editor to change
+the first file into the second file.  Long ago, this was the only output
+mode that was suitable for editing one file into another automatically;
+today, with 'patch', it is almost obsolete.  Use the '--ed' ('-e')
+option to select this output format.
+
+   Like the normal format (*note Normal::), this output format does not
+show any context; unlike the normal format, it does not include the
+information necessary to apply the diff in reverse (to produce the first
+file if all you have is the second file and the diff).
+
+   If the file 'd' contains the output of 'diff -e old new', then the
+command '(cat d && echo w) | ed - old' edits 'old' to make it a copy of
+'new'.  More generally, if 'd1', 'd2', ..., 'dN' contain the outputs of
+'diff -e old new1', 'diff -e new1 new2', ..., 'diff -e newN-1 newN',
+respectively, then the command '(cat d1 d2 ... dN && echo w) | ed - old'
+edits 'old' to make it a copy of 'newN'.
+
+* Menu:
+
+* Example ed::  A sample 'ed' script.
+* Detailed ed:: A detailed description of 'ed' format.
+
+
+File: diffutils.info-t,  Node: Example ed,  Next: Detailed ed,  Up: ed Scripts
+
+2.5.1.1 Example 'ed' Script
+...........................
+
+Here is the output of 'diff -e lao tzu' (*note Sample diff Input::, for
+the complete contents of the two files):
+
+     11a
+     They both may be called deep and profound.
+     Deeper and more profound,
+     The door of all subtleties!
+     .
+     4c
+     The named is the mother of all things.
+
+     .
+     1,2d
+
+
+File: diffutils.info-t,  Node: Detailed ed,  Prev: Example ed,  Up: ed Scripts
+
+2.5.1.2 Detailed Description of 'ed' Format
+...........................................
+
+The 'ed' output format consists of one or more hunks of differences.
+The changes closest to the ends of the files come first so that commands
+that change the number of lines do not affect how 'ed' interprets line
+numbers in succeeding commands.  'ed' format hunks look like this:
+
+     CHANGE-COMMAND
+     TO-FILE-LINE
+     TO-FILE-LINE...
+     .
+
+   Because 'ed' uses a single period on a line to indicate the end of
+input, GNU 'diff' protects lines of changes that contain a single period
+on a line by writing two periods instead, then writing a subsequent 'ed'
+command to change the two periods into one.  The 'ed' format cannot
+represent an incomplete line, so if the second file ends in a changed
+incomplete line, 'diff' reports an error and then pretends that a
+newline was appended.
+
+   There are three types of change commands.  Each consists of a line
+number or comma-separated range of lines in the first file and a single
+character indicating the kind of change to make.  All line numbers are
+the original line numbers in the file.  The types of change commands
+are:
+
+'La'
+     Add text from the second file after line L in the first file.  For
+     example, '8a' means to add the following lines after line 8 of file
+     1.
+
+'Rc'
+     Replace the lines in range R in the first file with the following
+     lines.  Like a combined add and delete, but more compact.  For
+     example, '5,7c' means change lines 5-7 of file 1 to read as the
+     text file 2.
+
+'Rd'
+     Delete the lines in range R from the first file.  For example,
+     '5,7d' means delete lines 5-7 of file 1.
+
+
+File: diffutils.info-t,  Node: Forward ed,  Next: RCS,  Prev: ed Scripts,  Up: Scripts
+
+2.5.2 Forward 'ed' Scripts
+--------------------------
+
+'diff' can produce output that is like an 'ed' script, but with hunks in
+forward (front to back) order.  The format of the commands is also
+changed slightly: command characters precede the lines they modify,
+spaces separate line numbers in ranges, and no attempt is made to
+disambiguate hunk lines consisting of a single period.  Like 'ed'
+format, forward 'ed' format cannot represent incomplete lines.
+
+   Forward 'ed' format is not very useful, because neither 'ed' nor
+'patch' can apply diffs in this format.  It exists mainly for
+compatibility with older versions of 'diff'.  Use the '-f' or
+'--forward-ed' option to select it.
+
+
+File: diffutils.info-t,  Node: RCS,  Prev: Forward ed,  Up: Scripts
+
+2.5.3 RCS Scripts
+-----------------
+
+The RCS output format is designed specifically for use by the Revision
+Control System, which is a set of free programs used for organizing
+different versions and systems of files.  Use the '--rcs' ('-n') option
+to select this output format.  It is like the forward 'ed' format (*note
+Forward ed::), but it can represent arbitrary changes to the contents of
+a file because it avoids the forward 'ed' format's problems with lines
+consisting of a single period and with incomplete lines.  Instead of
+ending text sections with a line consisting of a single period, each
+command specifies the number of lines it affects; a combination of the
+'a' and 'd' commands are used instead of 'c'.  Also, if the second file
+ends in a changed incomplete line, then the output also ends in an
+incomplete line.
+
+   Here is the output of 'diff -n lao tzu' (*note Sample diff Input::,
+for the complete contents of the two files):
+
+     d1 2
+     d4 1
+     a4 2
+     The named is the mother of all things.
+
+     a11 3
+     They both may be called deep and profound.
+     Deeper and more profound,
+     The door of all subtleties!
+
+
+File: diffutils.info-t,  Node: If-then-else,  Prev: Scripts,  Up: Output Formats
+
+2.6 Merging Files with If-then-else
+===================================
+
+You can use 'diff' to merge two files of C source code.  The output of
+'diff' in this format contains all the lines of both files.  Lines
+common to both files are output just once; the differing parts are
+separated by the C preprocessor directives '#ifdef NAME' or '#ifndef
+NAME', '#else', and '#endif'.  When compiling the output, you select
+which version to use by either defining or leaving undefined the macro
+NAME.
+
+   To merge two files, use 'diff' with the '-D NAME' or '--ifdef=NAME'
+option.  The argument NAME is the C preprocessor identifier to use in
+the '#ifdef' and '#ifndef' directives.
+
+   For example, if you change an instance of 'wait (&s)' to 'waitpid
+(-1, &s, 0)' and then merge the old and new files with the
+'--ifdef=HAVE_WAITPID' option, then the affected part of your code might
+look like this:
+
+         do {
+     #ifndef HAVE_WAITPID
+             if ((w = wait (&s)) < 0  &&  errno != EINTR)
+     #else /* HAVE_WAITPID */
+             if ((w = waitpid (-1, &s, 0)) < 0  &&  errno != EINTR)
+     #endif /* HAVE_WAITPID */
+                 return w;
+         } while (w != child);
+
+   You can specify formats for languages other than C by using line
+group formats and line formats, as described in the next sections.
+
+* Menu:
+
+* Line Group Formats::    Formats for general if-then-else line groups.
+* Line Formats::          Formats for each line in a line group.
+* Example If-then-else::  Sample if-then-else format output.
+* Detailed If-then-else:: A detailed description of if-then-else format.
+
+
+File: diffutils.info-t,  Node: Line Group Formats,  Next: Line Formats,  Up: If-then-else
+
+2.6.1 Line Group Formats
+------------------------
+
+Line group formats let you specify formats suitable for many
+applications that allow if-then-else input, including programming
+languages and text formatting languages.  A line group format specifies
+the output format for a contiguous group of similar lines.
+
+   For example, the following command compares the TeX files 'old' and
+'new', and outputs a merged file in which old regions are surrounded by
+'\begin{em}'-'\end{em}' lines, and new regions are surrounded by
+'\begin{bf}'-'\end{bf}' lines.
+
+     diff \
+        --old-group-format='\begin{em}
+     %<\end{em}
+     ' \
+        --new-group-format='\begin{bf}
+     %>\end{bf}
+     ' \
+        old new
+
+   The following command is equivalent to the above example, but it is a
+little more verbose, because it spells out the default line group
+formats.
+
+     diff \
+        --old-group-format='\begin{em}
+     %<\end{em}
+     ' \
+        --new-group-format='\begin{bf}
+     %>\end{bf}
+     ' \
+        --unchanged-group-format='%=' \
+        --changed-group-format='\begin{em}
+     %<\end{em}
+     \begin{bf}
+     %>\end{bf}
+     ' \
+        old new
+
+   Here is a more advanced example, which outputs a diff listing with
+headers containing line numbers in a "plain English" style.
+
+     diff \
+        --unchanged-group-format='' \
+        --old-group-format='-------- %dn line%(n=1?:s) deleted at %df:
+     %<' \
+        --new-group-format='-------- %dN line%(N=1?:s) added after %de:
+     %>' \
+        --changed-group-format='-------- %dn line%(n=1?:s) changed at %df:
+     %<-------- to:
+     %>' \
+        old new
+
+   To specify a line group format, use 'diff' with one of the options
+listed below.  You can specify up to four line group formats, one for
+each kind of line group.  You should quote FORMAT, because it typically
+contains shell metacharacters.
+
+'--old-group-format=FORMAT'
+     These line groups are hunks containing only lines from the first
+     file.  The default old group format is the same as the changed
+     group format if it is specified; otherwise it is a format that
+     outputs the line group as-is.
+
+'--new-group-format=FORMAT'
+     These line groups are hunks containing only lines from the second
+     file.  The default new group format is same as the changed group
+     format if it is specified; otherwise it is a format that outputs
+     the line group as-is.
+
+'--changed-group-format=FORMAT'
+     These line groups are hunks containing lines from both files.  The
+     default changed group format is the concatenation of the old and
+     new group formats.
+
+'--unchanged-group-format=FORMAT'
+     These line groups contain lines common to both files.  The default
+     unchanged group format is a format that outputs the line group
+     as-is.
+
+   In a line group format, ordinary characters represent themselves;
+conversion specifications start with '%' and have one of the following
+forms.
+
+'%<'
+     stands for the lines from the first file, including the trailing
+     newline.  Each line is formatted according to the old line format
+     (*note Line Formats::).
+
+'%>'
+     stands for the lines from the second file, including the trailing
+     newline.  Each line is formatted according to the new line format.
+
+'%='
+     stands for the lines common to both files, including the trailing
+     newline.  Each line is formatted according to the unchanged line
+     format.
+
+'%%'
+     stands for '%'.
+
+'%c'C''
+     where C is a single character, stands for C.  C may not be a
+     backslash or an apostrophe.  For example, '%c':'' stands for a
+     colon, even inside the then-part of an if-then-else format, which a
+     colon would normally terminate.
+
+'%c'\O''
+     where O is a string of 1, 2, or 3 octal digits, stands for the
+     character with octal code O.  For example, '%c'\0'' stands for a
+     null character.
+
+'FN'
+     where F is a 'printf' conversion specification and N is one of the
+     following letters, stands for N's value formatted with F.
+
+     'e'
+          The line number of the line just before the group in the old
+          file.
+
+     'f'
+          The line number of the first line in the group in the old
+          file; equals E + 1.
+
+     'l'
+          The line number of the last line in the group in the old file.
+
+     'm'
+          The line number of the line just after the group in the old
+          file; equals L + 1.
+
+     'n'
+          The number of lines in the group in the old file; equals L - F
+          + 1.
+
+     'E, F, L, M, N'
+          Likewise, for lines in the new file.
+
+     The 'printf' conversion specification can be '%d', '%o', '%x', or
+     '%X', specifying decimal, octal, lower case hexadecimal, or upper
+     case hexadecimal output respectively.  After the '%' the following
+     options can appear in sequence: a series of zero or more flags; an
+     integer specifying the minimum field width; and a period followed
+     by an optional integer specifying the minimum number of digits.
+     The flags are '-' for left-justification, ''' for separating the
+     digit into groups as specified by the 'LC_NUMERIC' locale category,
+     and '0' for padding with zeros instead of spaces.  For example,
+     '%5dN' prints the number of new lines in the group in a field of
+     width 5 characters, using the 'printf' format '"%5d"'.
+
+'(A=B?T:E)'
+     If A equals B then T else E.  A and B are each either a decimal
+     constant or a single letter interpreted as above.  This format spec
+     is equivalent to T if A's value equals B's; otherwise it is
+     equivalent to E.
+
+     For example, '%(N=0?no:%dN) line%(N=1?:s)' is equivalent to 'no
+     lines' if N (the number of lines in the group in the new file) is
+     0, to '1 line' if N is 1, and to '%dN lines' otherwise.
+
+
+File: diffutils.info-t,  Node: Line Formats,  Next: Example If-then-else,  Prev: Line Group Formats,  Up: If-then-else
+
+2.6.2 Line Formats
+------------------
+
+Line formats control how each line taken from an input file is output as
+part of a line group in if-then-else format.
+
+   For example, the following command outputs text with a one-character
+change indicator to the left of the text.  The first character of output
+is '-' for deleted lines, '|' for added lines, and a space for unchanged
+lines.  The formats contain newline characters where newlines are
+desired on output.
+
+     diff \
+        --old-line-format='-%l
+     ' \
+        --new-line-format='|%l
+     ' \
+        --unchanged-line-format=' %l
+     ' \
+        old new
+
+   To specify a line format, use one of the following options.  You
+should quote FORMAT, since it often contains shell metacharacters.
+
+'--old-line-format=FORMAT'
+     formats lines just from the first file.
+
+'--new-line-format=FORMAT'
+     formats lines just from the second file.
+
+'--unchanged-line-format=FORMAT'
+     formats lines common to both files.
+
+'--line-format=FORMAT'
+     formats all lines; in effect, it sets all three above options
+     simultaneously.
+
+   In a line format, ordinary characters represent themselves;
+conversion specifications start with '%' and have one of the following
+forms.
+
+'%l'
+     stands for the contents of the line, not counting its trailing
+     newline (if any).  This format ignores whether the line is
+     incomplete; *Note Incomplete Lines::.
+
+'%L'
+     stands for the contents of the line, including its trailing newline
+     (if any).  If a line is incomplete, this format preserves its
+     incompleteness.
+
+'%%'
+     stands for '%'.
+
+'%c'C''
+     where C is a single character, stands for C.  C may not be a
+     backslash or an apostrophe.  For example, '%c':'' stands for a
+     colon.
+
+'%c'\O''
+     where O is a string of 1, 2, or 3 octal digits, stands for the
+     character with octal code O.  For example, '%c'\0'' stands for a
+     null character.
+
+'Fn'
+     where F is a 'printf' conversion specification, stands for the line
+     number formatted with F.  For example, '%.5dn' prints the line
+     number using the 'printf' format '"%.5d"'.  *Note Line Group
+     Formats::, for more about printf conversion specifications.
+
+   The default line format is '%l' followed by a newline character.
+
+   If the input contains tab characters and it is important that they
+line up on output, you should ensure that '%l' or '%L' in a line format
+is just after a tab stop (e.g. by preceding '%l' or '%L' with a tab
+character), or you should use the '-t' or '--expand-tabs' option.
+
+   Taken together, the line and line group formats let you specify many
+different formats.  For example, the following command uses a format
+similar to normal 'diff' format.  You can tailor this command to get
+fine control over 'diff' output.
+
+     diff \
+        --old-line-format='< %l
+     ' \
+        --new-line-format='> %l
+     ' \
+        --old-group-format='%df%(f=l?:,%dl)d%dE
+     %<' \
+        --new-group-format='%dea%dF%(F=L?:,%dL)
+     %>' \
+        --changed-group-format='%df%(f=l?:,%dl)c%dF%(F=L?:,%dL)
+     %<---
+     %>' \
+        --unchanged-group-format='' \
+        old new
+
+
+File: diffutils.info-t,  Node: Example If-then-else,  Next: Detailed If-then-else,  Prev: Line Formats,  Up: If-then-else
+
+2.6.3 An Example of If-then-else Format
+---------------------------------------
+
+Here is the output of 'diff -DTWO lao tzu' (*note Sample diff Input::,
+for the complete contents of the two files):
+
+     #ifndef TWO
+     The Way that can be told of is not the eternal Way;
+     The name that can be named is not the eternal name.
+     #endif /* ! TWO */
+     The Nameless is the origin of Heaven and Earth;
+     #ifndef TWO
+     The Named is the mother of all things.
+     #else /* TWO */
+     The named is the mother of all things.
+
+     #endif /* TWO */
+     Therefore let there always be non-being,
+       so we may see their subtlety,
+     And let there always be being,
+       so we may see their outcome.
+     The two are the same,
+     But after they are produced,
+       they have different names.
+     #ifdef TWO
+     They both may be called deep and profound.
+     Deeper and more profound,
+     The door of all subtleties!
+     #endif /* TWO */
+
+
+File: diffutils.info-t,  Node: Detailed If-then-else,  Prev: Example If-then-else,  Up: If-then-else
+
+2.6.4 Detailed Description of If-then-else Format
+-------------------------------------------------
+
+For lines common to both files, 'diff' uses the unchanged line group
+format.  For each hunk of differences in the merged output format, if
+the hunk contains only lines from the first file, 'diff' uses the old
+line group format; if the hunk contains only lines from the second file,
+'diff' uses the new group format; otherwise, 'diff' uses the changed
+group format.
+
+   The old, new, and unchanged line formats specify the output format of
+lines from the first file, lines from the second file, and lines common
+to both files, respectively.
+
+   The option '--ifdef=NAME' is equivalent to the following sequence of
+options using shell syntax:
+
+     --old-group-format='#ifndef NAME
+     %<#endif /* ! NAME */
+     ' \
+     --new-group-format='#ifdef NAME
+     %>#endif /* NAME */
+     ' \
+     --unchanged-group-format='%=' \
+     --changed-group-format='#ifndef NAME
+     %<#else /* NAME */
+     %>#endif /* NAME */
+     '
+
+   You should carefully check the 'diff' output for proper nesting.  For
+example, when using the '-D NAME' or '--ifdef=NAME' option, you should
+check that if the differing lines contain any of the C preprocessor
+directives '#ifdef', '#ifndef', '#else', '#elif', or '#endif', they are
+nested properly and match.  If they don't, you must make corrections
+manually.  It is a good idea to carefully check the resulting code
+anyway to make sure that it really does what you want it to; depending
+on how the input files were produced, the output might contain duplicate
+or otherwise incorrect code.
+
+   The 'patch' '-D NAME' option behaves like the 'diff' '-D NAME'
+option, except it operates on a file and a diff to produce a merged
+file.  *Note patch Options::.
+
+
+File: diffutils.info-t,  Node: Incomplete Lines,  Next: Comparing Directories,  Prev: Output Formats,  Up: Top
+
+3 Incomplete Lines
+******************
+
+When an input file ends in a non-newline character, its last line is
+called an "incomplete line" because its last character is not a newline.
+All other lines are called "full lines" and end in a newline character.
+Incomplete lines do not match full lines unless differences in white
+space are ignored (*note White Space::).
+
+   An incomplete line is normally distinguished on output from a full
+line by a following line that starts with '\'.  However, the RCS format
+(*note RCS::) outputs the incomplete line as-is, without any trailing
+newline or following line.  The side by side format normally represents
+incomplete lines as-is, but in some cases uses a '\' or '/' gutter
+marker.  *Note Side by Side::.  The if-then-else line format preserves a
+line's incompleteness with '%L', and discards the newline with '%l'.
+*Note Line Formats::.  Finally, with the 'ed' and forward 'ed' output
+formats (*note Output Formats::) 'diff' cannot represent an incomplete
+line, so it pretends there was a newline and reports an error.
+
+   For example, suppose 'F' and 'G' are one-byte files that contain just
+'f' and 'g', respectively.  Then 'diff F G' outputs
+
+     1c1
+     < f
+     \ No newline at end of file
+     ---
+     > g
+     \ No newline at end of file
+
+(The exact message may differ in non-English locales.)  'diff -n F G'
+outputs the following without a trailing newline:
+
+     d1 1
+     a1 1
+     g
+
+'diff -e F G' reports two errors and outputs the following:
+
+     1c
+     g
+     .
+
+
+File: diffutils.info-t,  Node: Comparing Directories,  Next: Adjusting Output,  Prev: Incomplete Lines,  Up: Top
+
+4 Comparing Directories
+***********************
+
+You can use 'diff' to compare some or all of the files in two directory
+trees.  When both file name arguments to 'diff' are directories, it
+compares each file that is contained in both directories, examining file
+names in alphabetical order as specified by the 'LC_COLLATE' locale
+category.  Normally 'diff' is silent about pairs of files that contain
+no differences, but if you use the '--report-identical-files' ('-s')
+option, it reports pairs of identical files.  Normally 'diff' reports
+subdirectories common to both directories without comparing
+subdirectories' files, but if you use the '-r' or '--recursive' option,
+it compares every corresponding pair of files in the directory trees, as
+many levels deep as they go.
+
+   If only one file exists, 'diff' normally does not show its contents;
+it merely reports that one file exists but the other does not.  You can
+make 'diff' act as though the missing file is empty, so that it outputs
+the entire contents of the file that actually exists.  (It is output as
+either an insertion or a deletion, depending on whether the missing file
+is in the first or the second position.)  To do this, use the
+'--new-file' ('-N') option.  This option affects command-line arguments
+as well as files found via directory traversal; for example, 'diff -N a
+b' treats 'a' as empty if 'a' does not exist but 'b' does, and similarly
+'diff -N - b' treats standard input as empty if it is closed but 'b'
+exists.
+
+   If the older directory contains large files that are not in the newer
+directory, you can make the patch smaller by using the
+'--unidirectional-new-file' option instead of '-N'.  This option is like
+'-N' except that it inserts the contents only of files that appear in
+the second directory but not the first (that is, files that were added).
+At the top of the patch, write instructions for the user applying the
+patch to remove the files that were deleted before applying the patch.
+*Note Making Patches::, for more discussion of making patches for
+distribution.
+
+   To ignore some files while comparing directories, use the
+'--exclude=PATTERN' ('-x PATTERN') option.  This option ignores any
+files or subdirectories whose base names match the shell pattern
+PATTERN.  Unlike in the shell, a period at the start of the base of a
+file name matches a wildcard at the start of a pattern.  You should
+enclose PATTERN in quotes so that the shell does not expand it.  For
+example, the option '-x '*.[ao]'' ignores any file whose name ends with
+'.a' or '.o'.
+
+   This option accumulates if you specify it more than once.  For
+example, using the options '-x 'RCS' -x '*,v'' ignores any file or
+subdirectory whose base name is 'RCS' or ends with ',v'.
+
+   If you need to give this option many times, you can instead put the
+patterns in a file, one pattern per line, and use the
+'--exclude-from=FILE' ('-X FILE') option.  Trailing white space and
+empty lines are ignored in the pattern file.
+
+   If you have been comparing two directories and stopped partway
+through, later you might want to continue where you left off.  You can
+do this by using the '--starting-file=FILE' ('-S FILE') option.  This
+compares only the file FILE and all alphabetically later files in the
+topmost directory level.
+
+   If two directories differ only in that file names are lower case in
+one directory and upper case in the upper, 'diff' normally reports many
+differences because it compares file names in a case sensitive way.
+With the '--ignore-file-name-case' option, 'diff' ignores case
+differences in file names, so that for example the contents of the file
+'Tao' in one directory are compared to the contents of the file 'TAO' in
+the other.  The '--no-ignore-file-name-case' option cancels the effect
+of the '--ignore-file-name-case' option, reverting to the default
+behavior.
+
+   If an '--exclude=PATTERN' ('-x PATTERN') option, or an
+'--exclude-from=FILE' ('-X FILE') option, is specified while the
+'--ignore-file-name-case' option is in effect, case is ignored when
+excluding file names matching the specified patterns.
+
+   To tell 'diff' not to follow a symbolic link, use the
+'--no-dereference' option.
+
+
+File: diffutils.info-t,  Node: Adjusting Output,  Next: diff Performance,  Prev: Comparing Directories,  Up: Top
+
+5 Making 'diff' Output Prettier
+*******************************
+
+'diff' provides several ways to adjust the appearance of its output.
+These adjustments can be applied to any output format.
+
+* Menu:
+
+* Tabs::            Preserving the alignment of tab stops.
+* Trailing Blanks:: Suppressing blanks before empty output lines.
+* Pagination::      Page numbering and time-stamping 'diff' output.
+
+
+File: diffutils.info-t,  Node: Tabs,  Next: Trailing Blanks,  Up: Adjusting Output
+
+5.1 Preserving Tab Stop Alignment
+=================================
+
+The lines of text in some of the 'diff' output formats are preceded by
+one or two characters that indicate whether the text is inserted,
+deleted, or changed.  The addition of those characters can cause tabs to
+move to the next tab stop, throwing off the alignment of columns in the
+line.  GNU 'diff' provides two ways to make tab-aligned columns line up
+correctly.
+
+   The first way is to have 'diff' convert all tabs into the correct
+number of spaces before outputting them; select this method with the
+'--expand-tabs' ('-t') option.  To use this form of output with 'patch',
+you must give 'patch' the '-l' or '--ignore-white-space' option (*note
+Changed White Space::, for more information).  'diff' normally assumes
+that tab stops are set every 8 print columns, but this can be altered by
+the '--tabsize=COLUMNS' option.
+
+   The other method for making tabs line up correctly is to add a tab
+character instead of a space after the indicator character at the
+beginning of the line.  This ensures that all following tab characters
+are in the same position relative to tab stops that they were in the
+original files, so that the output is aligned correctly.  Its
+disadvantage is that it can make long lines too long to fit on one line
+of the screen or the paper.  It also does not work with the unified
+output format, which does not have a space character after the change
+type indicator character.  Select this method with the '-T' or
+'--initial-tab' option.
+
+
+File: diffutils.info-t,  Node: Trailing Blanks,  Next: Pagination,  Prev: Tabs,  Up: Adjusting Output
+
+5.2 Omitting trailing blanks
+============================
+
+When outputting lines in normal or context format, or outputting an
+unchanged line in unified format, 'diff' normally outputs a blank just
+before each line.  If the line is empty, the output of 'diff' therefore
+contains trailing blanks even though the input does not contain them.
+For example, when outputting an unchanged empty line in context format,
+'diff' normally outputs a line with two leading spaces.
+
+   Some text editors and email agents routinely delete trailing blanks,
+so it can be a problem to deal with diff output files that contain them.
+You can avoid this problem with the '--suppress-blank-empty' option.  It
+causes 'diff' to omit trailing blanks at the end of output lines in
+normal, context, and unified format, unless the trailing blanks were
+already present in the input.  This changes the output format slightly,
+so that output lines are guaranteed to never end in a blank unless an
+input line ends in a blank.  This format is less likely to be munged by
+text editors or by transmission via email.  It is accepted by GNU
+'patch' as well.
+
+
+File: diffutils.info-t,  Node: Pagination,  Prev: Trailing Blanks,  Up: Adjusting Output
+
+5.3 Paginating 'diff' Output
+============================
+
+It can be convenient to have long output page-numbered and time-stamped.
+The '--paginate' ('-l') option does this by sending the 'diff' output
+through the 'pr' program.  Here is what the page header might look like
+for 'diff -lc lao tzu':
+
+     2002-02-22 14:20                 diff -lc lao tzu                 Page 1
+
+
+File: diffutils.info-t,  Node: diff Performance,  Next: Comparing Three Files,  Prev: Adjusting Output,  Up: Top
+
+6 'diff' Performance Tradeoffs
+******************************
+
+GNU 'diff' runs quite efficiently; however, in some circumstances you
+can cause it to run faster or produce a more compact set of changes.
+
+   One way to improve 'diff' performance is to use hard or symbolic
+links to files instead of copies.  This improves performance because
+'diff' normally does not need to read two hard or symbolic links to the
+same file, since their contents must be identical.  For example, suppose
+you copy a large directory hierarchy, make a few changes to the copy,
+and then often use 'diff -r' to compare the original to the copy.  If
+the original files are read-only, you can greatly improve performance by
+creating the copy using hard or symbolic links (e.g., with GNU 'cp -lR'
+or 'cp -sR').  Before editing a file in the copy for the first time, you
+should break the link and replace it with a regular copy.
+
+   You can also affect the performance of GNU 'diff' by giving it
+options that change the way it compares files.  Performance has more
+than one dimension.  These options improve one aspect of performance at
+the cost of another, or they improve performance in some cases while
+hurting it in others.
+
+   The way that GNU 'diff' determines which lines have changed always
+comes up with a near-minimal set of differences.  Usually it is good
+enough for practical purposes.  If the 'diff' output is large, you might
+want 'diff' to use a modified algorithm that sometimes produces a
+smaller set of differences.  The '--minimal' ('-d') option does this;
+however, it can also cause 'diff' to run more slowly than usual, so it
+is not the default behavior.
+
+   When the files you are comparing are large and have small groups of
+changes scattered throughout them, you can use the '--speed-large-files'
+option to make a different modification to the algorithm that 'diff'
+uses.  If the input files have a constant small density of changes, this
+option speeds up the comparisons without changing the output.  If not,
+'diff' might produce a larger set of differences; however, the output
+will still be correct.
+
+   Normally 'diff' discards the prefix and suffix that is common to both
+files before it attempts to find a minimal set of differences.  This
+makes 'diff' run faster, but occasionally it may produce non-minimal
+output.  The '--horizon-lines=LINES' option prevents 'diff' from
+discarding the last LINES lines of the prefix and the first LINES lines
+of the suffix.  This gives 'diff' further opportunities to find a
+minimal output.
+
+   Suppose a run of changed lines includes a sequence of lines at one
+end and there is an identical sequence of lines just outside the other
+end.  The 'diff' command is free to choose which identical sequence is
+included in the hunk.  In this case, 'diff' normally shifts the hunk's
+boundaries when this merges adjacent hunks, or shifts a hunk's lines
+towards the end of the file.  Merging hunks can make the output look
+nicer in some cases.
+
+
+File: diffutils.info-t,  Node: Comparing Three Files,  Next: diff3 Merging,  Prev: diff Performance,  Up: Top
+
+7 Comparing Three Files
+***********************
+
+Use the program 'diff3' to compare three files and show any differences
+among them.  ('diff3' can also merge files; see *note diff3 Merging::).
+
+   The "normal" 'diff3' output format shows each hunk of differences
+without surrounding context.  Hunks are labeled depending on whether
+they are two-way or three-way, and lines are annotated by their location
+in the input files.
+
+   *Note Invoking diff3::, for more information on how to run 'diff3'.
+
+* Menu:
+
+* Sample diff3 Input::    Sample 'diff3' input for examples.
+* Example diff3 Normal::  Sample output in the normal format.
+* Detailed diff3 Normal:: A detailed description of normal output format.
+* diff3 Hunks::           The format of normal output format.
+
+
+File: diffutils.info-t,  Node: Sample diff3 Input,  Next: Example diff3 Normal,  Up: Comparing Three Files
+
+7.1 A Third Sample Input File
+=============================
+
+Here is a third sample file that will be used in examples to illustrate
+the output of 'diff3' and how various options can change it.  The first
+two files are the same that we used for 'diff' (*note Sample diff
+Input::).  This is the third sample file, called 'tao':
+
+     The Way that can be told of is not the eternal Way;
+     The name that can be named is not the eternal name.
+     The Nameless is the origin of Heaven and Earth;
+     The named is the mother of all things.
+
+     Therefore let there always be non-being,
+       so we may see their subtlety,
+     And let there always be being,
+       so we may see their result.
+     The two are the same,
+     But after they are produced,
+       they have different names.
+
+       -- The Way of Lao-Tzu, tr. Wing-tsit Chan
+
+
+File: diffutils.info-t,  Node: Example diff3 Normal,  Next: Detailed diff3 Normal,  Prev: Sample diff3 Input,  Up: Comparing Three Files
+
+7.2 An Example of 'diff3' Normal Format
+=======================================
+
+Here is the output of the command 'diff3 lao tzu tao' (*note Sample
+diff3 Input::, for the complete contents of the files).  Notice that it
+shows only the lines that are different among the three files.
+
+     ====2
+     1:1,2c
+     3:1,2c
+       The Way that can be told of is not the eternal Way;
+       The name that can be named is not the eternal name.
+     2:0a
+     ====1
+     1:4c
+       The Named is the mother of all things.
+     2:2,3c
+     3:4,5c
+       The named is the mother of all things.
+  
+     ====3
+     1:8c
+     2:7c
+         so we may see their outcome.
+     3:9c
+         so we may see their result.
+     ====
+     1:11a
+     2:11,13c
+       They both may be called deep and profound.
+       Deeper and more profound,
+       The door of all subtleties!
+     3:13,14c
+  
+         -- The Way of Lao-Tzu, tr. Wing-tsit Chan
+
+
+File: diffutils.info-t,  Node: Detailed diff3 Normal,  Next: diff3 Hunks,  Prev: Example diff3 Normal,  Up: Comparing Three Files
+
+7.3 Detailed Description of 'diff3' Normal Format
+=================================================
+
+Each hunk begins with a line marked '===='.  Three-way hunks have plain
+'====' lines, and two-way hunks have '1', '2', or '3' appended to
+specify which of the three input files differ in that hunk.  The hunks
+contain copies of two or three sets of input lines each preceded by one
+or two commands identifying where the lines came from.
+
+   Normally, two spaces precede each copy of an input line to
+distinguish it from the commands.  But with the '--initial-tab' ('-T')
+option, 'diff3' uses a tab instead of two spaces; this lines up tabs
+correctly.  *Note Tabs::, for more information.
+
+   Commands take the following forms:
+
+'FILE:La'
+     This hunk appears after line L of file FILE, and contains no lines
+     in that file.  To edit this file to yield the other files, one must
+     append hunk lines taken from the other files.  For example, '1:11a'
+     means that the hunk follows line 11 in the first file and contains
+     no lines from that file.
+
+'FILE:Rc'
+     This hunk contains the lines in the range R of file FILE.  The
+     range R is a comma-separated pair of line numbers, or just one
+     number if there is only one line.  To edit this file to yield the
+     other files, one must change the specified lines to be the lines
+     taken from the other files.  For example, '2:11,13c' means that the
+     hunk contains lines 11 through 13 from the second file.
+
+   If the last line in a set of input lines is incomplete (*note
+Incomplete Lines::), it is distinguished on output from a full line by a
+following line that starts with '\'.
+
+
+File: diffutils.info-t,  Node: diff3 Hunks,  Prev: Detailed diff3 Normal,  Up: Comparing Three Files
+
+7.4 'diff3' Hunks
+=================
+
+Groups of lines that differ in two or three of the input files are
+called "diff3 hunks", by analogy with 'diff' hunks (*note Hunks::).  If
+all three input files differ in a 'diff3' hunk, the hunk is called a
+"three-way hunk"; if just two input files differ, it is a "two-way
+hunk".
+
+   As with 'diff', several solutions are possible.  When comparing the
+files 'A', 'B', and 'C', 'diff3' normally finds 'diff3' hunks by merging
+the two-way hunks output by the two commands 'diff A B' and 'diff A C'.
+This does not necessarily minimize the size of the output, but
+exceptions should be rare.
+
+   For example, suppose 'F' contains the three lines 'a', 'b', 'f', 'G'
+contains the lines 'g', 'b', 'g', and 'H' contains the lines 'a', 'b',
+'h'.  'diff3 F G H' might output the following:
+
+     ====2
+     1:1c
+     3:1c
+       a
+     2:1c
+       g
+     ====
+     1:3c
+       f
+     2:3c
+       g
+     3:3c
+       h
+
+because it found a two-way hunk containing 'a' in the first and third
+files and 'g' in the second file, then the single line 'b' common to all
+three files, then a three-way hunk containing the last line of each
+file.
+
+
+File: diffutils.info-t,  Node: diff3 Merging,  Next: Interactive Merging,  Prev: Comparing Three Files,  Up: Top
+
+8 Merging From a Common Ancestor
+********************************
+
+When two people have made changes to copies of the same file, 'diff3'
+can produce a merged output that contains both sets of changes together
+with warnings about conflicts.
+
+   One might imagine programs with names like 'diff4' and 'diff5' to
+compare more than three files simultaneously, but in practice the need
+rarely arises.  You can use 'diff3' to merge three or more sets of
+changes to a file by merging two change sets at a time.
+
+   'diff3' can incorporate changes from two modified versions into a
+common preceding version.  This lets you merge the sets of changes
+represented by the two newer files.  Specify the common ancestor version
+as the second argument and the two newer versions as the first and third
+arguments, like this:
+
+     diff3 MINE OLDER YOURS
+
+You can remember the order of the arguments by noting that they are in
+alphabetical order.
+
+   You can think of this as subtracting OLDER from YOURS and adding the
+result to MINE, or as merging into MINE the changes that would turn
+OLDER into YOURS.  This merging is well-defined as long as MINE and
+OLDER match in the neighborhood of each such change.  This fails to be
+true when all three input files differ or when only OLDER differs; we
+call this a "conflict".  When all three input files differ, we call the
+conflict an "overlap".
+
+   'diff3' gives you several ways to handle overlaps and conflicts.  You
+can omit overlaps or conflicts, or select only overlaps, or mark
+conflicts with special '<<<<<<<' and '>>>>>>>' lines.
+
+   'diff3' can output the merge results as an 'ed' script that that can
+be applied to the first file to yield the merged output.  However, it is
+usually better to have 'diff3' generate the merged output directly; this
+bypasses some problems with 'ed'.
+
+* Menu:
+
+* Which Changes::            Selecting changes to incorporate.
+* Marking Conflicts::        Marking conflicts.
+* Bypassing ed::             Generating merged output directly.
+* Merging Incomplete Lines:: How 'diff3' merges incomplete lines.
+* Saving the Changed File::  Emulating System V behavior.
+
+
+File: diffutils.info-t,  Node: Which Changes,  Next: Marking Conflicts,  Up: diff3 Merging
+
+8.1 Selecting Which Changes to Incorporate
+==========================================
+
+You can select all unmerged changes from OLDER to YOURS for merging into
+MINE with the '--ed' ('-e') option.  You can select only the
+nonoverlapping unmerged changes with '--easy-only' ('-3'), and you can
+select only the overlapping changes with '--overlap-only' ('-x').
+
+   The '-e', '-3' and '-x' options select only "unmerged changes", i.e.
+changes where MINE and YOURS differ; they ignore changes from OLDER to
+YOURS where MINE and YOURS are identical, because they assume that such
+changes have already been merged.  If this assumption is not a safe one,
+you can use the '--show-all' ('-A') option (*note Marking Conflicts::).
+
+   Here is the output of the command 'diff3' with each of these three
+options (*note Sample diff3 Input::, for the complete contents of the
+files).  Notice that '-e' outputs the union of the disjoint sets of
+changes output by '-3' and '-x'.
+
+   Output of 'diff3 -e lao tzu tao':
+     11a
+
+       -- The Way of Lao-Tzu, tr. Wing-tsit Chan
+     .
+     8c
+       so we may see their result.
+     .
+
+   Output of 'diff3 -3 lao tzu tao':
+     8c
+       so we may see their result.
+     .
+
+   Output of 'diff3 -x lao tzu tao':
+     11a
+
+       -- The Way of Lao-Tzu, tr. Wing-tsit Chan
+     .
+
+
+File: diffutils.info-t,  Node: Marking Conflicts,  Next: Bypassing ed,  Prev: Which Changes,  Up: diff3 Merging
+
+8.2 Marking Conflicts
+=====================
+
+'diff3' can mark conflicts in the merged output by bracketing them with
+special marker lines.  A conflict that comes from two files A and B is
+marked as follows:
+
+     <<<<<<< A
+     lines from A
+     =======
+     lines from B
+     >>>>>>> B
+
+   A conflict that comes from three files A, B and C is marked as
+follows:
+
+     <<<<<<< A
+     lines from A
+     ||||||| B
+     lines from B
+     =======
+     lines from C
+     >>>>>>> C
+
+   The '--show-all' ('-A') option acts like the '-e' option, except that
+it brackets conflicts, and it outputs all changes from OLDER to YOURS,
+not just the unmerged changes.  Thus, given the sample input files
+(*note Sample diff3 Input::), 'diff3 -A lao tzu tao' puts brackets
+around the conflict where only 'tzu' differs:
+
+     <<<<<<< tzu
+     =======
+     The Way that can be told of is not the eternal Way;
+     The name that can be named is not the eternal name.
+     >>>>>>> tao
+
+   And it outputs the three-way conflict as follows:
+
+     <<<<<<< lao
+     ||||||| tzu
+     They both may be called deep and profound.
+     Deeper and more profound,
+     The door of all subtleties!
+     =======
+
+       -- The Way of Lao-Tzu, tr. Wing-tsit Chan
+     >>>>>>> tao
+
+   The '--show-overlap' ('-E') option outputs less information than the
+'--show-all' ('-A') option, because it outputs only unmerged changes,
+and it never outputs the contents of the second file.  Thus the '-E'
+option acts like the '-e' option, except that it brackets the first and
+third files from three-way overlapping changes.  Similarly, '-X' acts
+like '-x', except it brackets all its (necessarily overlapping) changes.
+For example, for the three-way overlapping change above, the '-E' and
+'-X' options output the following:
+
+     <<<<<<< lao
+     =======
+
+       -- The Way of Lao-Tzu, tr. Wing-tsit Chan
+     >>>>>>> tao
+
+   If you are comparing files that have meaningless or uninformative
+names, you can use the '--label=LABEL' option to show alternate names in
+the '<<<<<<<', '|||||||' and '>>>>>>>' brackets.  This option can be
+given up to three times, once for each input file.  Thus 'diff3 -A
+--label X --label Y --label Z A B C' acts like 'diff3 -A A B C', except
+that the output looks like it came from files named 'X', 'Y' and 'Z'
+rather than from files named 'A', 'B' and 'C'.
+
+
+File: diffutils.info-t,  Node: Bypassing ed,  Next: Merging Incomplete Lines,  Prev: Marking Conflicts,  Up: diff3 Merging
+
+8.3 Generating the Merged Output Directly
+=========================================
+
+With the '--merge' ('-m') option, 'diff3' outputs the merged file
+directly.  This is more efficient than using 'ed' to generate it, and
+works even with non-text files that 'ed' would reject.  If you specify
+'-m' without an 'ed' script option, '-A' is assumed.
+
+   For example, the command 'diff3 -m lao tzu tao' (*note Sample diff3
+Input:: for a copy of the input files) would output the following:
+
+     <<<<<<< tzu
+     =======
+     The Way that can be told of is not the eternal Way;
+     The name that can be named is not the eternal name.
+     >>>>>>> tao
+     The Nameless is the origin of Heaven and Earth;
+     The Named is the mother of all things.
+     Therefore let there always be non-being,
+       so we may see their subtlety,
+     And let there always be being,
+       so we may see their result.
+     The two are the same,
+     But after they are produced,
+       they have different names.
+     <<<<<<< lao
+     ||||||| tzu
+     They both may be called deep and profound.
+     Deeper and more profound,
+     The door of all subtleties!
+     =======
+
+       -- The Way of Lao-Tzu, tr. Wing-tsit Chan
+     >>>>>>> tao
+
+
+File: diffutils.info-t,  Node: Merging Incomplete Lines,  Next: Saving the Changed File,  Prev: Bypassing ed,  Up: diff3 Merging
+
+8.4 How 'diff3' Merges Incomplete Lines
+=======================================
+
+With '-m', incomplete lines (*note Incomplete Lines::) are simply copied
+to the output as they are found; if the merged output ends in an
+conflict and one of the input files ends in an incomplete line,
+succeeding '|||||||', '=======' or '>>>>>>>' brackets appear somewhere
+other than the start of a line because they are appended to the
+incomplete line.
+
+   Without '-m', if an 'ed' script option is specified and an incomplete
+line is found, 'diff3' generates a warning and acts as if a newline had
+been present.
+
+
+File: diffutils.info-t,  Node: Saving the Changed File,  Prev: Merging Incomplete Lines,  Up: diff3 Merging
+
+8.5 Saving the Changed File
+===========================
+
+Traditional Unix 'diff3' generates an 'ed' script without the trailing
+'w' and 'q' commands that save the changes.  System V 'diff3' generates
+these extra commands.  GNU 'diff3' normally behaves like traditional
+Unix 'diff3', but with the '-i' option it behaves like System V 'diff3'
+and appends the 'w' and 'q' commands.
+
+   The '-i' option requires one of the 'ed' script options '-AeExX3',
+and is incompatible with the merged output option '-m'.
+
+
+File: diffutils.info-t,  Node: Interactive Merging,  Next: Merging with patch,  Prev: diff3 Merging,  Up: Top
+
+9 Interactive Merging with 'sdiff'
+**********************************
+
+With 'sdiff', you can merge two files interactively based on a
+side-by-side '-y' format comparison (*note Side by Side::).  Use
+'--output=FILE' ('-o FILE') to specify where to put the merged text.
+*Note Invoking sdiff::, for more details on the options to 'sdiff'.
+
+   Another way to merge files interactively is to use the Emacs Lisp
+package 'emerge'.  *Note Emerge: (emacs)Emerge, for more information.
+
+* Menu:
+
+* sdiff Option Summary:: Summary of 'sdiff' options.
+* Merge Commands::       Merging two files interactively.
+
+
+File: diffutils.info-t,  Node: sdiff Option Summary,  Next: Merge Commands,  Up: Interactive Merging
+
+9.1 Specifying 'diff' Options to 'sdiff'
+========================================
+
+The following 'sdiff' options have the same meaning as for 'diff'.
+*Note diff Options::, for the use of these options.
+
+     -a -b -d -i -t -v
+     -B -E -I REGEXP -Z
+
+     --expand-tabs
+     --ignore-blank-lines  --ignore-case
+     --ignore-matching-lines=REGEXP  --ignore-space-change
+     --ignore-tab-expansion  --ignore-trailing-space
+     --left-column  --minimal  --speed-large-files
+     --strip-trailing-cr  --suppress-common-lines
+     --tabsize=COLUMNS  --text  --version  --width=COLUMNS
+
+   For historical reasons, 'sdiff' has alternate names for some options.
+The '-l' option is equivalent to the '--left-column' option, and
+similarly '-s' is equivalent to '--suppress-common-lines'.  The meaning
+of the 'sdiff' '-w' and '-W' options is interchanged from that of
+'diff': with 'sdiff', '-w COLUMNS' is equivalent to '--width=COLUMNS',
+and '-W' is equivalent to '--ignore-all-space'.  'sdiff' without the
+'-o' option is equivalent to 'diff' with the '--side-by-side' ('-y')
+option (*note Side by Side::).
+
+
+File: diffutils.info-t,  Node: Merge Commands,  Prev: sdiff Option Summary,  Up: Interactive Merging
+
+9.2 Merge Commands
+==================
+
+Groups of common lines, with a blank gutter, are copied from the first
+file to the output.  After each group of differing lines, 'sdiff'
+prompts with '%' and pauses, waiting for one of the following commands.
+Follow each command with <RET>.
+
+'e'
+     Discard both versions.  Invoke a text editor on an empty temporary
+     file, then copy the resulting file to the output.
+
+'eb'
+     Concatenate the two versions, edit the result in a temporary file,
+     then copy the edited result to the output.
+
+'ed'
+     Like 'eb', except precede each version with a header that shows
+     what file and lines the version came from.
+
+'el'
+'e1'
+     Edit a copy of the left version, then copy the result to the
+     output.
+
+'er'
+'e2'
+     Edit a copy of the right version, then copy the result to the
+     output.
+
+'l'
+'1'
+     Copy the left version to the output.
+
+'q'
+     Quit.
+
+'r'
+'2'
+     Copy the right version to the output.
+
+'s'
+     Silently copy common lines.
+
+'v'
+     Verbosely copy common lines.  This is the default.
+
+   The text editor invoked is specified by the 'EDITOR' environment
+variable if it is set.  The default is system-dependent.
+
+
+File: diffutils.info-t,  Node: Merging with patch,  Next: Making Patches,  Prev: Interactive Merging,  Up: Top
+
+10 Merging with 'patch'
+***********************
+
+'patch' takes comparison output produced by 'diff' and applies the
+differences to a copy of the original file, producing a patched version.
+With 'patch', you can distribute just the changes to a set of files
+instead of distributing the entire file set; your correspondents can
+apply 'patch' to update their copy of the files with your changes.
+'patch' automatically determines the diff format, skips any leading or
+trailing headers, and uses the headers to determine which file to patch.
+This lets your correspondents feed a mail message containing a
+difference listing directly to 'patch'.
+
+   'patch' detects and warns about common problems like forward patches.
+It saves any patches that it could not apply.  It can also maintain a
+'patchlevel.h' file to ensure that your correspondents apply diffs in
+the proper order.
+
+   'patch' accepts a series of diffs in its standard input, usually
+separated by headers that specify which file to patch.  It applies
+'diff' hunks (*note Hunks::) one by one.  If a hunk does not exactly
+match the original file, 'patch' uses heuristics to try to patch the
+file as well as it can.  If no approximate match can be found, 'patch'
+rejects the hunk and skips to the next hunk.  'patch' normally replaces
+each file F with its new version, putting reject hunks (if any) into
+'F.rej'.
+
+   *Note Invoking patch::, for detailed information on the options to
+'patch'.
+
+* Menu:
+
+* patch Input::            Selecting the type of 'patch' input.
+* Revision Control::       Getting files from RCS, SCCS, etc.
+* Imperfect::              Dealing with imperfect patches.
+* Creating and Removing::  Creating and removing files with a patch.
+* Patching Time Stamps::   Updating time stamps on patched files.
+* Multiple Patches::       Handling multiple patches in a file.
+* patch Directories::      Changing directory and stripping directories.
+* Backups::                Whether backup files are made.
+* Backup Names::           Backup file names.
+* Reject Names::           Reject file names.
+* patch Messages::         Messages and questions 'patch' can produce.
+* patch and POSIX::        Conformance to the POSIX standard.
+* patch and Tradition::    GNU versus traditional 'patch'.
+
+
+File: diffutils.info-t,  Node: patch Input,  Next: Revision Control,  Up: Merging with patch
+
+10.1 Selecting the 'patch' Input Format
+=======================================
+
+'patch' normally determines which 'diff' format the patch file uses by
+examining its contents.  For patch files that contain particularly
+confusing leading text, you might need to use one of the following
+options to force 'patch' to interpret the patch file as a certain format
+of diff.  The output formats listed here are the only ones that 'patch'
+can understand.
+
+'-c'
+'--context'
+     context diff.
+
+'-e'
+'--ed'
+     'ed' script.
+
+'-n'
+'--normal'
+     normal diff.
+
+'-u'
+'--unified'
+     unified diff.
+
+
+File: diffutils.info-t,  Node: Revision Control,  Next: Imperfect,  Prev: patch Input,  Up: Merging with patch
+
+10.2 Revision Control
+=====================
+
+If a nonexistent input file is under a revision control system supported
+by 'patch', 'patch' normally asks the user whether to get (or check out)
+the file from the revision control system.  Patch currently supports
+RCS, ClearCase and SCCS.  Under RCS and SCCS, 'patch' also asks when the
+input file is read-only and matches the default version in the revision
+control system.
+
+   The '--get=NUM' ('-g NUM') option affects access to files under
+supported revision control systems.  If NUM is positive, 'patch' gets
+the file without asking the user; if zero, 'patch' neither asks the user
+nor gets the file; and if negative, 'patch' asks the user before getting
+the file.  The default value of NUM 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.  *Note
+patch and POSIX::.
+
+   The choice of revision control system is unaffected by the
+'VERSION_CONTROL' environment variable (*note Backup Names::).
+
+
+File: diffutils.info-t,  Node: Imperfect,  Next: Creating and Removing,  Prev: Revision Control,  Up: Merging with patch
+
+10.3 Applying Imperfect Patches
+===============================
+
+'patch' tries to skip any leading text in the patch file, apply the
+diff, and then skip any trailing text.  Thus you can feed a mail message
+directly to 'patch', and it should work.  If the entire diff is indented
+by a constant amount of white space, 'patch' automatically ignores the
+indentation.  If a context diff contains trailing carriage return on
+each line, 'patch' automatically ignores the carriage return.  If a
+context diff has been encapsulated by prepending '- ' to lines beginning
+with '-' as per Internet RFC 934
+(ftp://ftp.isi.edu/in-notes/rfc934.txt), 'patch' automatically
+unencapsulates the input.
+
+   However, certain other types of imperfect input require user
+intervention or testing.
+
+* Menu:
+
+* Changed White Space:: When tabs and spaces don't match exactly.
+* Reversed Patches::    Applying reversed patches correctly.
+* Inexact::             Helping 'patch' find close matches.
+* Dry Runs::            Predicting what 'patch' will do.
+
+
+File: diffutils.info-t,  Node: Changed White Space,  Next: Reversed Patches,  Up: Imperfect
+
+10.3.1 Applying Patches with Changed White Space
+------------------------------------------------
+
+Sometimes mailers, editors, or other programs change spaces into tabs,
+or vice versa.  If this happens to a patch file or an input file, the
+files might look the same, but 'patch' will not be able to match them
+properly.  If this problem occurs, use the '-l' or
+'--ignore-white-space' option, which makes 'patch' compare blank
+characters (i.e. spaces and tabs) loosely so that any nonempty sequence
+of blanks in the patch file matches any nonempty sequence of blanks in
+the input files.  Non-blank characters must still match exactly.  Each
+line of the context must still match a line in the input file.
+
+
+File: diffutils.info-t,  Node: Reversed Patches,  Next: Inexact,  Prev: Changed White Space,  Up: Imperfect
+
+10.3.2 Applying Reversed Patches
+--------------------------------
+
+Sometimes people run 'diff' with the new file first instead of second.
+This creates a diff that is "reversed".  To apply such patches, give
+'patch' the '--reverse' ('-R') option.  'patch' then attempts to swap
+each hunk around before applying it.  Rejects come out in the swapped
+format.
+
+   Often 'patch' can guess that the patch is reversed.  If the first
+hunk of a patch fails, 'patch' reverses the hunk to see if it can apply
+it that way.  If it can, 'patch' asks you if you want to have the '-R'
+option set; if it can't, 'patch' continues to apply the patch normally.
+This method cannot detect a reversed patch if it is a normal diff and
+the first command is an append (which should have been a delete) since
+appends always succeed, because a null context matches anywhere.  But
+most patches add or change lines rather than delete them, so most
+reversed normal diffs begin with a delete, which fails, and 'patch'
+notices.
+
+   If you apply a patch that you have already applied, 'patch' thinks it
+is a reversed patch and offers to un-apply the patch.  This could be
+construed as a feature.  If you did this inadvertently and you don't
+want to un-apply the patch, just answer 'n' to this offer and to the
+subsequent "apply anyway" question--or type 'C-c' to kill the 'patch'
+process.
+
+
+File: diffutils.info-t,  Node: Inexact,  Next: Dry Runs,  Prev: Reversed Patches,  Up: Imperfect
+
+10.3.3 Helping 'patch' Find Inexact Matches
+-------------------------------------------
+
+For context diffs, and to a lesser extent normal diffs, 'patch' can
+detect when the line numbers mentioned in the patch are incorrect, and
+it attempts to find the correct place to apply each hunk of the patch.
+As a first guess, it takes the line number mentioned in the hunk, plus
+or minus any offset used in applying the previous hunk.  If that is not
+the correct place, 'patch' scans both forward and backward 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 it cannot find such a place, and it is reading a context or unified
+diff, and the maximum fuzz factor is set to 1 or more, then 'patch'
+makes another scan, ignoring the first and last line of context.  If
+that fails, and the maximum fuzz factor is set to 2 or more, it makes
+another scan, ignoring the first two and last two lines of context are
+ignored.  It continues similarly if the maximum fuzz factor is larger.
+
+   The '--fuzz=LINES' ('-F LINES') option sets the maximum fuzz factor
+to LINES.  This option only applies to context and unified diffs; it
+ignores up to LINES lines while looking for the place to install a hunk.
+Note that a larger fuzz factor increases the odds of making a faulty
+patch.  The default fuzz factor is 2; there is no point to setting it to
+more than the number of lines of context in the diff, ordinarily 3.
+
+   If 'patch' cannot find a place to install a hunk of the patch, it
+writes the hunk out to a reject file (*note Reject Names::, for
+information on how reject files are named).  It writes out rejected
+hunks in context format no matter what form the input patch is in.  If
+the input is a normal or 'ed' diff, many of the contexts are simply
+null.  The line numbers on the hunks in the reject file may be different
+from those in the patch file: they show the approximate location where
+'patch' thinks the failed hunks belong in the new file rather than in
+the old one.
+
+   If the '--verbose' option is given, then as it completes each hunk
+'patch' tells you whether the hunk succeeded or failed, and if it
+failed, on which line (in the new file) 'patch' thinks the hunk should
+go.  If this is different from the line number specified in the diff, it
+tells you the offset.  A single large offset _may_ indicate that 'patch'
+installed a hunk in the wrong place.  'patch' also tells you if it used
+a fuzz factor to make the match, in which case you should also be
+slightly suspicious.
+
+   'patch' cannot tell if the line numbers are off in an 'ed' script,
+and can only detect wrong line numbers in a normal diff when it finds a
+change or delete command.  It may have the same problem with a context
+diff using a fuzz factor equal to or greater than the number of lines of
+context shown in the diff (typically 3).  In these cases, you should
+probably look at a context diff between your original and patched input
+files to see if the changes make sense.  Compiling without errors is a
+pretty good indication that the patch worked, but not a guarantee.
+
+   A patch against an empty file applies to a nonexistent file, and vice
+versa.  *Note Creating and Removing::.
+
+   'patch' usually produces the correct results, even when it must make
+many guesses.  However, the results are guaranteed only when the patch
+is applied to an exact copy of the file that the patch was generated
+from.
+
+
+File: diffutils.info-t,  Node: Dry Runs,  Prev: Inexact,  Up: Imperfect
+
+10.3.4 Predicting what 'patch' will do
+--------------------------------------
+
+It may not be obvious in advance what 'patch' will do with a complicated
+or poorly formatted patch.  If you are concerned that the input might
+cause 'patch' to modify the wrong files, you can use the '--dry-run'
+option, which causes 'patch' to print the results of applying patches
+without actually changing any files.  You can then inspect the
+diagnostics generated by the dry run to see whether 'patch' will modify
+the files that you expect.  If the patch does not do what you want, you
+can modify the patch (or the other options to 'patch') and try another
+dry run.  Once you are satisfied with the proposed patch you can apply
+it by invoking 'patch' as before, but this time without the '--dry-run'
+option.
+
+
+File: diffutils.info-t,  Node: Creating and Removing,  Next: Patching Time Stamps,  Prev: Imperfect,  Up: Merging with patch
+
+10.4 Creating and Removing Files
+================================
+
+Sometimes when comparing two directories, a file may exist in one
+directory but not the other.  If you give 'diff' the '--new-file' ('-N')
+option, or if you supply an old or new file that is named '/dev/null' or
+is empty and is dated the Epoch (1970-01-01 00:00:00 UTC), 'diff'
+outputs a patch that adds or deletes the contents of this file.  When
+given such a patch, 'patch' normally creates a new file or removes the
+old file.  However, when conforming to POSIX (*note patch and POSIX::),
+'patch' does not remove the old file, but leaves it empty.  The
+'--remove-empty-files' ('-E') option causes 'patch' to remove output
+files that are empty after applying a patch, even if the patch does not
+appear to be one that removed the file.
+
+   If the patch appears to create a file that already exists, 'patch'
+asks for confirmation before applying the patch.
+
+
+File: diffutils.info-t,  Node: Patching Time Stamps,  Next: Multiple Patches,  Prev: Creating and Removing,  Up: Merging with patch
+
+10.5 Updating Time Stamps on Patched Files
+==========================================
+
+When 'patch' updates a file, it normally sets the file's last-modified
+time stamp to the current time of day.  If you are using 'patch' to
+track a software distribution, this can cause 'make' to incorrectly
+conclude that a patched file is out of date.  For example, if 'syntax.c'
+depends on 'syntax.y', and 'patch' updates 'syntax.c' and then
+'syntax.y', then 'syntax.c' will normally appear to be out of date with
+respect to 'syntax.y' even though its contents are actually up to date.
+
+   The '--set-utc' ('-Z') option causes 'patch' to set a patched file's
+modification and access times to the time stamps given in context diff
+headers.  If the context diff headers do not specify a time zone, they
+are assumed to use Coordinated Universal Time (UTC, often known as GMT).
+
+   The '--set-time' ('-T') option acts like '-Z' or '--set-utc', except
+that it assumes that the context diff headers' time stamps use local
+time instead of UTC.  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.  If the context diff
+headers specify a time zone, this option is equivalent to '--set-utc'
+('-Z').
+
+   'patch' normally refrains from setting a file's time stamps if the
+file's original last-modified time stamp does not match the time given
+in the diff header, of if the file's contents do not exactly match the
+patch.  However, if the '--force' ('-f') option is given, the file's
+time stamps are set regardless.
+
+   Due to the limitations of the current 'diff' format, 'patch' cannot
+update the times of files whose contents have not changed.  Also, if you
+set file time stamps to values other than the current time of day, you
+should also 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.
+
+
+File: diffutils.info-t,  Node: Multiple Patches,  Next: patch Directories,  Prev: Patching Time Stamps,  Up: Merging with patch
+
+10.6 Multiple Patches in a File
+===============================
+
+If the patch file contains more than one patch, and if you do not
+specify an input file on the command line, 'patch' tries to apply each
+patch as if they came from separate patch files.  This means that it
+determines the name of the file to patch for each patch, and that it
+examines the leading text before each patch for file names and
+prerequisite revision level (*note Making Patches::, for more on that
+topic).
+
+   'patch' uses the following rules to intuit a file name from the
+leading text before a patch.  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, and SCCS (*note Revision
+     Control::), and no named files exist but an RCS, ClearCase, or SCCS
+     master is found, 'patch' selects the first named file with an RCS,
+     ClearCase, or SCCS master.
+
+   * If no named files exist, no RCS, ClearCase, 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.
+
+   *Note patch and POSIX::, to see whether 'patch' is conforming to
+POSIX.
+
+
+File: diffutils.info-t,  Node: patch Directories,  Next: Backups,  Prev: Multiple Patches,  Up: Merging with patch
+
+10.7 Applying Patches in Other Directories
+==========================================
+
+The '--directory=DIRECTORY' ('-d DIRECTORY') option to 'patch' makes
+directory DIRECTORY the current directory for interpreting both file
+names in the patch file, and file names given as arguments to other
+options (such as '-B' and '-o').  For example, while in a mail reading
+program, you can patch a file in the '/usr/src/emacs' directory directly
+from a message containing the patch like this:
+
+     | patch -d /usr/src/emacs
+
+   Sometimes the file names given in a patch contain leading
+directories, but you keep your files in a directory different from the
+one given in the patch.  In those cases, you can use the
+'--strip=NUMBER' ('-pNUMBER') option to set the file name strip count to
+NUMBER.  The strip count tells 'patch' how many slashes, along with the
+directory names between them, to strip from the front of file names.  A
+sequence of one or more adjacent slashes is counted as a single slash.
+By default, 'patch' strips off all leading directories, leaving just the
+base file names.
+
+   For example, suppose the file name in the patch file is
+'/gnu/src/emacs/etc/NEWS'.  Using '-p0' gives the entire file name
+unmodified, '-p1' gives 'gnu/src/emacs/etc/NEWS' (no leading slash),
+'-p4' gives 'etc/NEWS', and not specifying '-p' at all gives 'NEWS'.
+
+   'patch' looks for each file (after any slashes have been stripped) in
+the current directory, or if you used the '-d DIRECTORY' option, in that
+directory.
+
+
+File: diffutils.info-t,  Node: Backups,  Next: Backup Names,  Prev: patch Directories,  Up: Merging with patch
+
+10.8 Backup Files
+=================
+
+Normally, 'patch' creates a backup file if the patch does not exactly
+match the original input file, because in that case the original data
+might not be recovered if you undo the patch with 'patch -R' (*note
+Reversed Patches::).  However, when conforming to POSIX, 'patch' does
+not create backup files by default.  *Note patch and POSIX::.
+
+   The '--backup' ('-b') option causes 'patch' to make a backup file
+regardless of whether the patch matches the original input.  The
+'--backup-if-mismatch' option causes 'patch' to create backup files for
+mismatches files; this is the default when not conforming to POSIX.  The
+'--no-backup-if-mismatch' option causes 'patch' to not create backup
+files, even for mismatched patches; this is the default when conforming
+to POSIX.
+
+   When backing up a file that does not exist, an empty, unreadable
+backup file is created as a placeholder to represent the nonexistent
+file.
+
+
+File: diffutils.info-t,  Node: Backup Names,  Next: Reject Names,  Prev: Backups,  Up: Merging with patch
+
+10.9 Backup File Names
+======================
+
+Normally, 'patch' renames an original input file into a backup file by
+appending to its name the extension '.orig', or '~' if using '.orig'
+would make the backup file name too long.(1)  The '-z BACKUP-SUFFIX' or
+'--suffix=BACKUP-SUFFIX' option causes 'patch' to use BACKUP-SUFFIX as
+the backup extension instead.
+
+   Alternately, you can specify the extension for backup files with the
+'SIMPLE_BACKUP_SUFFIX' environment variable, which the options override.
+
+   'patch' can also create numbered backup files the way GNU Emacs does.
+With this method, instead of having a single backup of each file,
+'patch' makes a new backup file name each time it patches a file.  For
+example, the backups of a file named 'sink' would be called,
+successively, 'sink.~1~', 'sink.~2~', 'sink.~3~', etc.
+
+   The '-V BACKUP-STYLE' or '--version-control=BACKUP-STYLE' option
+takes as an argument a method for creating backup file names.  You can
+alternately control the type of backups that 'patch' makes with the
+'PATCH_VERSION_CONTROL' environment variable, which the '-V' option
+overrides.  If 'PATCH_VERSION_CONTROL' is not set, the 'VERSION_CONTROL'
+environment variable is used instead.  Please note that these options
+and variables control backup file names; they do not affect the choice
+of revision control system (*note Revision Control::).
+
+   The values of these environment variables and the argument to the
+'-V' option are like the GNU Emacs 'version-control' variable (*note
+(emacs)Backup Names::, for more information on backup versions in
+Emacs).  They also recognize synonyms that are more descriptive.  The
+valid values are listed below; unique abbreviations are acceptable.
+
+'t'
+'numbered'
+     Always make numbered backups.
+
+'nil'
+'existing'
+     Make numbered backups of files that already have them, simple
+     backups of the others.  This is the default.
+
+'never'
+'simple'
+     Always make simple backups.
+
+   You can also tell 'patch' to prepend a prefix, such as a directory
+name, to produce backup file names.  The '--prefix=PREFIX' ('-B PREFIX')
+option makes backup files by prepending PREFIX to them.  The
+'--basename-prefix=PREFIX' ('-Y PREFIX') prepends PREFIX to the last
+file name component of backup file names instead; for example, '-Y ~'
+causes the backup name for 'dir/file.c' to be 'dir/~file.c'.  If you use
+either of these prefix options, the suffix-based options are ignored.
+
+   If you specify the output file with the '-o' option, that file is the
+one that is backed up, not the input file.
+
+   Options that affect the names of backup files do not affect whether
+backups are made.  For example, if you specify the
+'--no-backup-if-mismatch' option, none of the options described in this
+section have any affect, because no backups are made.
+
+   ---------- Footnotes ----------
+
+   (1) A coding error in GNU 'patch' version 2.5.4 causes it to always
+use '~', but this should be fixed in the next release.
+
+
+File: diffutils.info-t,  Node: Reject Names,  Next: patch Messages,  Prev: Backup Names,  Up: Merging with patch
+
+10.10 Reject File Names
+=======================
+
+The names for reject files (files containing patches that 'patch' could
+not find a place to apply) are normally the name of the output file with
+'.rej' appended (or '#' if using '.rej' would make the backup file name
+too long).
+
+   Alternatively, you can tell 'patch' to place all of the rejected
+patches in a single file.  The '-r REJECT-FILE' or
+'--reject-file=REJECT-FILE' option uses REJECT-FILE as the reject file
+name.
+
+
+File: diffutils.info-t,  Node: patch Messages,  Next: patch and POSIX,  Prev: Reject Names,  Up: Merging with patch
+
+10.11 Messages and Questions from 'patch'
+=========================================
+
+'patch' can produce a variety of messages, especially if it has trouble
+decoding its input.  In a few situations where it's not sure how to
+proceed, 'patch' normally prompts you for more information from the
+keyboard.  There are options to produce more or fewer messages, to have
+it not ask for keyboard input, and to affect the way that file names are
+quoted in messages.
+
+* Menu:
+
+* More or Fewer Messages::    Controlling the verbosity of 'patch'.
+* patch and Keyboard Input::  Inhibiting keyboard input.
+* patch Quoting Style::       Quoting file names in diagnostics.
+
+   'patch' exits with status 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, you should check the exit
+status, so you don't apply a later patch to a partially patched file.
+
+
+File: diffutils.info-t,  Node: More or Fewer Messages,  Next: patch and Keyboard Input,  Up: patch Messages
+
+10.11.1 Controlling the Verbosity of 'patch'
+--------------------------------------------
+
+You can cause 'patch' to produce more messages by using the '--verbose'
+option.  For example, when you give this option, the message 'Hmm...'
+indicates that 'patch' is reading text in the patch file, attempting to
+determine whether there is a patch in that text, and if so, what kind of
+patch it is.
+
+   You can inhibit all terminal output from 'patch', unless an error
+occurs, by using the '-s', '--quiet', or '--silent' option.
+
+
+File: diffutils.info-t,  Node: patch and Keyboard Input,  Next: patch Quoting Style,  Prev: More or Fewer Messages,  Up: patch Messages
+
+10.11.2 Inhibiting Keyboard Input
+---------------------------------
+
+There are two ways you can prevent 'patch' from asking you any
+questions.  The '--force' ('-f') option assumes that you know what you
+are doing.  It causes 'patch' to do the following:
+
+   * Skip patches that do not contain file names in their headers.
+
+   * Patch files even though they have the wrong version for the
+     'Prereq:' line in the patch;
+
+   * Assume that patches are not reversed even if they look like they
+     are.
+
+The '--batch' ('-t') option is similar to '-f', in that it suppresses
+questions, but it makes somewhat different assumptions:
+
+   * Skip patches that do not contain file names in their headers (the
+     same as '-f').
+
+   * Skip patches for which the file has the wrong version for the
+     'Prereq:' line in the patch;
+
+   * Assume that patches are reversed if they look like they are.
+
+
+File: diffutils.info-t,  Node: patch Quoting Style,  Prev: patch and Keyboard Input,  Up: patch Messages
+
+10.11.3 'patch' Quoting Style
+-----------------------------
+
+When 'patch' outputs a file name in a diagnostic message, it can format
+the name in any of several ways.  This can be useful to output file
+names unambiguously, even if they contain punctuation or special
+characters like newlines.  The '--quoting-style=WORD' option controls
+how names are output.  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', but this default may
+change in a future version of 'patch'.
+
+
+File: diffutils.info-t,  Node: patch and POSIX,  Next: patch and Tradition,  Prev: patch Messages,  Up: Merging with patch
+
+10.12 'patch' and the POSIX Standard
+====================================
+
+If you specify the '--posix' option, or set the 'POSIXLY_CORRECT'
+environment variable, 'patch' conforms 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.  *Note Multiple Patches::.
+
+   * Do not remove files that are removed by a diff.  *Note Creating and
+     Removing::.
+
+   * Do not ask whether to get files from RCS, ClearCase, or SCCS.
+     *Note Revision Control::.
+
+   * Require that all options precede the files in the command line.
+
+   * Do not backup files, even when there is a mismatch.  *Note
+     Backups::.
+
+
+File: diffutils.info-t,  Node: patch and Tradition,  Prev: patch and POSIX,  Up: Merging with patch
+
+10.13 GNU 'patch' and Traditional 'patch'
+=========================================
+
+The current version of GNU 'patch' normally follows the POSIX standard.
+*Note patch and POSIX::, for the few exceptions to this general rule.
+
+   Unfortunately, POSIX redefined the behavior of 'patch' in several
+important ways.  You should be aware of the following differences if you
+must interoperate with traditional 'patch', or with GNU 'patch' version
+2.1 and earlier.
+
+   * 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 '--backup' ('-b') 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.
+
+     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
+
+
+File: diffutils.info-t,  Node: Making Patches,  Next: Invoking cmp,  Prev: Merging with patch,  Up: Top
+
+11 Tips for Making and Using Patches
+************************************
+
+Use some common sense when making and using patches.  For example, when
+sending bug fixes to a program's maintainer, send several small patches,
+one per independent subject, instead of one large, harder-to-digest
+patch that covers all the subjects.
+
+   Here are some other things you should keep in mind if you are going
+to distribute patches for updating a software package.
+
+* Menu:
+
+* Tips for Patch Producers::    Advice for making patches.
+* Tips for Patch Consumers::    Advice for using patches.
+* Avoiding Common Mistakes::    Avoiding common mistakes when using 'patch'.
+* Generating Smaller Patches::  How to generate smaller patches.
+
+
+File: diffutils.info-t,  Node: Tips for Patch Producers,  Next: Tips for Patch Consumers,  Up: Making Patches
+
+11.1 Tips for Patch Producers
+=============================
+
+To create a patch that changes an older version of a package into a
+newer version, first make a copy of the older and newer versions in
+adjacent subdirectories.  It is common to do that by unpacking 'tar'
+archives of the two versions.
+
+   To generate the patch, use 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 '-N' option lets the patch create
+and remove files; '-a' lets the patch update non-text files; '-u'
+generates useful time stamps and enough context; and '-r' lets the patch
+update subdirectories.  Here is an example command, using Bourne shell
+syntax:
+
+     diff -Naur gcc-3.0.3 gcc-3.0.4
+
+   Tell your recipients how to apply the patches.  This should include
+which working directory to use, and which 'patch' options to use; the
+option '-p1' is recommended.  Test your procedure by pretending to be a
+recipient and applying your patches to a copy of the original files.
+
+   *Note Avoiding Common Mistakes::, for how to avoid common mistakes
+when generating a patch.
+
+
+File: diffutils.info-t,  Node: Tips for Patch Consumers,  Next: Avoiding Common Mistakes,  Prev: Tips for Patch Producers,  Up: Making Patches
+
+11.2 Tips for Patch Consumers
+=============================
+
+A patch producer should tell recipients how to apply the patches, so the
+first rule of thumb for a patch consumer is to follow the instructions
+supplied with the patch.
+
+   GNU 'diff' can analyze files with arbitrarily long lines and files
+that end in incomplete lines.  However, older versions of 'patch' cannot
+patch such files.  If you are having trouble applying such patches, try
+upgrading to a recent version of GNU 'patch'.
+
+
+File: diffutils.info-t,  Node: Avoiding Common Mistakes,  Next: Generating Smaller Patches,  Prev: Tips for Patch Consumers,  Up: Making Patches
+
+11.3 Avoiding Common Mistakes
+=============================
+
+When producing a patch for multiple files, apply 'diff' to directories
+whose names do not have slashes.  This reduces confusion when the patch
+consumer specifies the '-pNUMBER' option, since this option can have
+surprising results when the old and new file names have different
+numbers of slashes.  For example, do not send a patch with a header that
+looks like this:
+
+     diff -Naur v2.0.29/prog/README prog/README
+     --- v2.0.29/prog/README	2002-03-10 23:30:39.942229878 -0800
+     +++ prog/README	2002-03-17 20:49:32.442260588 -0800
+
+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	2002-03-10 23:30:39.942229878 -0800
+     +++ v2.0.30/prog/README	2002-03-17 20:49:32.442260588 -0800
+
+   Make sure you have specified the file names correctly, either in a
+context diff header or with an 'Index:' line.  Take care to not send out
+reversed patches, since these make people wonder whether they have
+already applied the patch.
+
+   Avoid sending patches that compare backup file names like
+'README.orig' or 'README~', 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'.
+
+   To save people from partially applying a patch before other patches
+that should have gone before it, you can make the first patch in the
+patch file update a file with a name like 'patchlevel.h' or 'version.c',
+which contains a patch level or version number.  If the input file
+contains the wrong version number, 'patch' will complain immediately.
+
+   An even clearer way to prevent this problem is to put a 'Prereq:'
+line before the patch.  If the leading text in the patch file contains a
+line that starts with 'Prereq:', 'patch' takes the next word from that
+line (normally a version number) and checks whether the next input file
+contains that word, preceded and followed by either white space or a
+newline.  If not, 'patch' prompts you for confirmation before
+proceeding.  This makes it difficult to accidentally apply patches in
+the wrong order.
+
+
+File: diffutils.info-t,  Node: Generating Smaller Patches,  Prev: Avoiding Common Mistakes,  Up: Making Patches
+
+11.4 Generating Smaller Patches
+===============================
+
+The simplest way to generate a patch is to use 'diff -Naur' (*note Tips
+for Patch Producers::), but you might be able to reduce the size of the
+patch by renaming or removing some files before making the patch.  If
+the older version of the package contains any files that the newer
+version does not, or if any files have been renamed between the two
+versions, make a list of 'rm' and 'mv' commands for the user to execute
+in the old version directory before applying the patch.  Then run those
+commands yourself in the scratch directory.
+
+   If there are any files that you don't need to include in the patch
+because they can easily be rebuilt from other files (for example, 'TAGS'
+and output from 'yacc' and 'makeinfo'), exclude them from the patch by
+giving 'diff' the '-x PATTERN' option (*note Comparing Directories::).
+If you want your patch to modify a derived file because your recipients
+lack tools to build it, make sure that the patch for the derived file
+follows any patches for files that it depends on, so that the
+recipients' time stamps will not confuse 'make'.
+
+   Now you can create the patch using 'diff -Naur'.  Make sure to
+specify the scratch directory first and the newer directory second.
+
+   Add to the top of the patch a note telling the user any 'rm' and 'mv'
+commands to run before applying the patch.  Then you can remove the
+scratch directory.
+
+   You can also shrink the patch size by using fewer lines of context,
+but bear in mind that 'patch' typically needs at least two lines for
+proper operation when patches do not exactly match the input files.
+
+
+File: diffutils.info-t,  Node: Invoking cmp,  Next: Invoking diff,  Prev: Making Patches,  Up: Top
+
+12 Invoking 'cmp'
+*****************
+
+The 'cmp' command compares two files, and if they differ, tells the
+first byte and line number where they differ or reports that one file is
+a prefix of the other.  Bytes and lines are numbered starting with 1.
+The arguments of 'cmp' are as follows:
+
+     cmp OPTIONS... FROM-FILE [TO-FILE [FROM-SKIP [TO-SKIP]]]
+
+   The file name '-' is always the standard input.  'cmp' also uses the
+standard input if one file name is omitted.  The FROM-SKIP and TO-SKIP
+operands specify how many bytes to ignore at the start of each file;
+they are equivalent to the '--ignore-initial=FROM-SKIP:TO-SKIP' option.
+
+   By default, 'cmp' outputs nothing if the two files have the same
+contents.  If one file is a prefix of the other, 'cmp' prints to
+standard error a message of the following form:
+
+     cmp: EOF on SHORTER-FILE
+
+   Otherwise, 'cmp' prints to standard output a message of the following
+form:
+
+     FROM-FILE TO-FILE differ: char BYTE-NUMBER, line LINE-NUMBER
+
+   The message formats can differ outside the POSIX locale.  Also, POSIX
+allows the EOF message to be followed by a blank and some additional
+information.
+
+   An exit status of 0 means no differences were found, 1 means some
+differences were found, and 2 means trouble.
+
+* Menu:
+
+* cmp Options:: Summary of options to 'cmp'.
+
+
+File: diffutils.info-t,  Node: cmp Options,  Up: Invoking cmp
+
+12.1 Options to 'cmp'
+=====================
+
+Below is a summary of all of the options that GNU 'cmp' accepts.  Most
+options have two equivalent names, one of which is a single letter
+preceded by '-', and the other of which is a long name preceded by '--'.
+Multiple single letter options (unless they take an argument) can be
+combined into a single command line word: '-bl' is equivalent to '-b
+-l'.
+
+'-b'
+'--print-bytes'
+     Print the differing bytes.  Display control bytes as a '^' followed
+     by a letter of the alphabet and precede bytes that have the high
+     bit set with 'M-' (which stands for "meta").
+
+'--help'
+     Output a summary of usage and then exit.
+
+'-i SKIP'
+'--ignore-initial=SKIP'
+     Ignore any differences in the first SKIP bytes of the input files.
+     Treat files with fewer than SKIP bytes as if they are empty.  If
+     SKIP is of the form 'FROM-SKIP:TO-SKIP', skip the first FROM-SKIP
+     bytes of the first input file and the first TO-SKIP bytes of the
+     second.
+
+'-l'
+'--verbose'
+     Output the (decimal) byte numbers and (octal) values of all
+     differing bytes, instead of the default standard output.  Each
+     output line contains a differing byte's number relative to the
+     start of the input, followed by the differing byte values.  Byte
+     numbers start at 1.  Also, output the EOF message if one file is
+     shorter than the other.
+
+'-n COUNT'
+'--bytes=COUNT'
+     Compare at most COUNT input bytes.
+
+'-s'
+'--quiet'
+'--silent'
+     Do not print anything; only return an exit status indicating
+     whether the files differ.
+
+'-v'
+'--version'
+     Output version information and then exit.
+
+   In the above table, operands that are byte counts are normally
+decimal, but may be preceded by '0' for octal and '0x' for hexadecimal.
+
+   A byte count can be followed by a suffix to specify a multiple of
+that count; in this case an omitted integer is understood to be 1.  A
+bare size letter, or one followed by 'iB', specifies a multiple using
+powers of 1024.  A size letter followed by 'B' specifies powers of 1000
+instead.  For example, '-n 4M' and '-n 4MiB' are equivalent to '-n
+4194304', whereas '-n 4MB' is equivalent to '-n 4000000'.  This notation
+is upward compatible with the SI prefixes
+(http://www.bipm.fr/enus/3_SI/si-prefixes.html) for decimal multiples
+and with the IEC 60027-2 prefixes for binary multiples
+(http://physics.nist.gov/cuu/Units/binary.html).
+
+   The following suffixes are defined.  Large sizes like '1Y' may be
+rejected by your computer due to limitations of its arithmetic.
+
+'kB'
+     kilobyte: 10^3 = 1000.
+'k'
+'K'
+'KiB'
+     kibibyte: 2^10 = 1024.  'K' is special: the SI prefix is 'k' and
+     the IEC 60027-2 prefix is 'Ki', but tradition and POSIX use 'k' to
+     mean 'KiB'.
+'MB'
+     megabyte: 10^6 = 1,000,000.
+'M'
+'MiB'
+     mebibyte: 2^20 = 1,048,576.
+'GB'
+     gigabyte: 10^9 = 1,000,000,000.
+'G'
+'GiB'
+     gibibyte: 2^30 = 1,073,741,824.
+'TB'
+     terabyte: 10^12 = 1,000,000,000,000.
+'T'
+'TiB'
+     tebibyte: 2^40 = 1,099,511,627,776.
+'PB'
+     petabyte: 10^15 = 1,000,000,000,000,000.
+'P'
+'PiB'
+     pebibyte: 2^50 = 1,125,899,906,842,624.
+'EB'
+     exabyte: 10^18 = 1,000,000,000,000,000,000.
+'E'
+'EiB'
+     exbibyte: 2^60 = 1,152,921,504,606,846,976.
+'ZB'
+     zettabyte: 10^21 = 1,000,000,000,000,000,000,000
+'Z'
+'ZiB'
+     2^70 = 1,180,591,620,717,411,303,424.  ('Zi' is a GNU extension to
+     IEC 60027-2.)
+'YB'
+     yottabyte: 10^24 = 1,000,000,000,000,000,000,000,000.
+'Y'
+'YiB'
+     2^80 = 1,208,925,819,614,629,174,706,176.  ('Yi' is a GNU extension
+     to IEC 60027-2.)
+
+
+File: diffutils.info-t,  Node: Invoking diff,  Next: Invoking diff3,  Prev: Invoking cmp,  Up: Top
+
+13 Invoking 'diff'
+******************
+
+The format for running the 'diff' command is:
+
+     diff OPTIONS... FILES...
+
+   In the simplest case, two file names FROM-FILE and TO-FILE are given,
+and 'diff' compares the contents of FROM-FILE and TO-FILE.  A file name
+of '-' stands for the standard input.
+
+   If one file is a directory and the other is not, 'diff' compares the
+file in the directory whose name is that of the non-directory.  The
+non-directory file must not be '-'.
+
+   If two file names are given and both are directories, 'diff' compares
+corresponding files in both directories, in alphabetical order; this
+comparison is not recursive unless the '--recursive' ('-r') option is
+given.  'diff' never compares the actual contents of a directory as if
+it were a file.  The file that is fully specified may not be standard
+input, because standard input is nameless and the notion of "file with
+the same name" does not apply.
+
+   If the '--from-file=FILE' option is given, the number of file names
+is arbitrary, and FILE is compared to each named file.  Similarly, if
+the '--to-file=FILE' option is given, each named file is compared to
+FILE.
+
+   'diff' options begin with '-', so normally file names may not begin
+with '-'.  However, '--' as an argument by itself treats the remaining
+arguments as file names even if they begin with '-'.
+
+   An exit status of 0 means no differences were found, 1 means some
+differences were found, and 2 means trouble.
+
+* Menu:
+
+* diff Options:: Summary of options to 'diff'.
+
+
+File: diffutils.info-t,  Node: diff Options,  Up: Invoking diff
+
+13.1 Options to 'diff'
+======================
+
+Below is a summary of all of the options that GNU 'diff' accepts.  Most
+options have two equivalent names, one of which is a single letter
+preceded by '-', and the other of which is a long name preceded by '--'.
+Multiple single letter options (unless they take an argument) can be
+combined into a single command line word: '-ac' is equivalent to '-a
+-c'.  Long named options can be abbreviated to any unique prefix of
+their name.  Brackets ([ and ]) indicate that an option takes an
+optional argument.
+
+'-a'
+'--text'
+     Treat all files as text and compare them line-by-line, even if they
+     do not seem to be text.  *Note Binary::.
+
+'-b'
+'--ignore-space-change'
+     Ignore changes in amount of white space.  *Note White Space::.
+
+'-B'
+'--ignore-blank-lines'
+     Ignore changes that just insert or delete blank lines.  *Note Blank
+     Lines::.
+
+'--binary'
+     Read and write data in binary mode.  *Note Binary::.
+
+'-c'
+     Use the context output format, showing three lines of context.
+     *Note Context Format::.
+
+'--color [=WHEN]'
+     Specify whether to use color for distinguishing different contexts,
+     like header, added or removed lines.  WHEN may be omitted, or one
+     of:
+        * none Do not use color at all.  This is the default when no
+          -color option is specified.
+        * auto Use color only if standard output is a terminal.
+        * always Always use color.
+     Specifying '--color' and no WHEN is equivalent to '--color=auto'.
+
+'-C LINES'
+'--context[=LINES]'
+     Use the context output format, showing LINES (an integer) lines of
+     context, or three if LINES is not given.  *Note Context Format::.
+     For proper operation, 'patch' typically needs at least two lines of
+     context.
+
+     For compatibility 'diff' also supports an obsolete option syntax
+     '-LINES' that has effect when combined with '-c', '-p', or '-u'.
+     New scripts should use '-U LINES' ('-C LINES') instead.
+
+'--changed-group-format=FORMAT'
+     Use FORMAT to output a line group containing differing lines from
+     both files in if-then-else format.  *Note Line Group Formats::.
+
+'-d'
+'--minimal'
+     Change the algorithm perhaps find a smaller set of changes.  This
+     makes 'diff' slower (sometimes much slower).  *Note diff
+     Performance::.
+
+'-D NAME'
+'--ifdef=NAME'
+     Make merged '#ifdef' format output, conditional on the preprocessor
+     macro NAME.  *Note If-then-else::.
+
+'-e'
+'--ed'
+     Make output that is a valid 'ed' script.  *Note ed Scripts::.
+
+'-E'
+'--ignore-tab-expansion'
+     Ignore changes due to tab expansion.  *Note White Space::.
+
+'-f'
+'--forward-ed'
+     Make output that looks vaguely like an 'ed' script but has changes
+     in the order they appear in the file.  *Note Forward ed::.
+
+'-F REGEXP'
+'--show-function-line=REGEXP'
+     In context and unified format, for each hunk of differences, show
+     some of the last preceding line that matches REGEXP.  *Note
+     Specified Headings::.
+
+'--from-file=FILE'
+     Compare FILE to each operand; FILE may be a directory.
+
+'--help'
+     Output a summary of usage and then exit.
+
+'--horizon-lines=LINES'
+     Do not discard the last LINES lines of the common prefix and the
+     first LINES lines of the common suffix.  *Note diff Performance::.
+
+'-i'
+'--ignore-case'
+     Ignore changes in case; consider upper- and lower-case letters
+     equivalent.  *Note Case Folding::.
+
+'-I REGEXP'
+'--ignore-matching-lines=REGEXP'
+     Ignore changes that just insert or delete lines that match REGEXP.
+     *Note Specified Lines::.
+
+'--ignore-file-name-case'
+     Ignore case when comparing file names.  For example, recursive
+     comparison of 'd' to 'e' might compare the contents of 'd/Init' and
+     'e/inIt'.  At the top level, 'diff d inIt' might compare the
+     contents of 'd/Init' and 'inIt'.  *Note Comparing Directories::.
+
+'-l'
+'--paginate'
+     Pass the output through 'pr' to paginate it.  *Note Pagination::.
+
+'-L LABEL'
+'--label=LABEL'
+     Use LABEL instead of the file name in the context format (*note
+     Context Format::) and unified format (*note Unified Format::)
+     headers.  *Note RCS::.
+
+'--left-column'
+     Print only the left column of two common lines in side by side
+     format.  *Note Side by Side Format::.
+
+'--line-format=FORMAT'
+     Use FORMAT to output all input lines in if-then-else format.  *Note
+     Line Formats::.
+
+'-n'
+'--rcs'
+     Output RCS-format diffs; like '-f' except that each command
+     specifies the number of lines affected.  *Note RCS::.
+
+'-N'
+'--new-file'
+     If one file is missing, treat it as present but empty.  *Note
+     Comparing Directories::.
+
+'--new-group-format=FORMAT'
+     Use FORMAT to output a group of lines taken from just the second
+     file in if-then-else format.  *Note Line Group Formats::.
+
+'--new-line-format=FORMAT'
+     Use FORMAT to output a line taken from just the second file in
+     if-then-else format.  *Note Line Formats::.
+
+'--no-dereference'
+     Act on symbolic links themselves instead of what they point to.
+     Two symbolic links are deemed equal only when each points to
+     precisely the same name.
+
+'--old-group-format=FORMAT'
+     Use FORMAT to output a group of lines taken from just the first
+     file in if-then-else format.  *Note Line Group Formats::.
+
+'--old-line-format=FORMAT'
+     Use FORMAT to output a line taken from just the first file in
+     if-then-else format.  *Note Line Formats::.
+
+'-p'
+'--show-c-function'
+     Show which C function each change is in.  *Note C Function
+     Headings::.
+
+'--palette=PALETTE'
+     Specify what color palette to use when colored output is enabled.
+     It defaults to 'rs=0:hd=1:ad=32:de=31:ln=36' for red deleted lines,
+     green added lines, cyan line numbers, bold header.
+
+     Supported capabilities are as follows.
+
+     'ad=32'
+
+          SGR substring for added lines.  The default is green
+          foreground.
+
+     'de=31'
+
+          SGR substring for deleted lines.  The default is red
+          foreground.
+
+     'hd=1'
+
+          SGR substring for chunk header.  The default is bold
+          foreground.
+
+     'ln=36'
+
+          SGR substring for line numbers.  The default is cyan
+          foreground.
+
+'-q'
+'--brief'
+     Report only whether the files differ, not the details of the
+     differences.  *Note Brief::.
+
+'-r'
+'--recursive'
+     When comparing directories, recursively compare any subdirectories
+     found.  *Note Comparing Directories::.
+
+'-s'
+'--report-identical-files'
+     Report when two files are the same.  *Note Comparing Directories::.
+
+'-S FILE'
+'--starting-file=FILE'
+     When comparing directories, start with the file FILE.  This is used
+     for resuming an aborted comparison.  *Note Comparing Directories::.
+
+'--speed-large-files'
+     Use heuristics to speed handling of large files that have numerous
+     scattered small changes.  *Note diff Performance::.
+
+'--strip-trailing-cr'
+     Strip any trailing carriage return at the end of an input line.
+     *Note Binary::.
+
+'--suppress-common-lines'
+     Do not print common lines in side by side format.  *Note Side by
+     Side Format::.
+
+'-t'
+'--expand-tabs'
+     Expand tabs to spaces in the output, to preserve the alignment of
+     tabs in the input files.  *Note Tabs::.
+
+'-T'
+'--initial-tab'
+     Output a tab rather than a space before the text of a line in
+     normal or context format.  This causes the alignment of tabs in the
+     line to look normal.  *Note Tabs::.
+
+'--tabsize=COLUMNS'
+     Assume that tab stops are set every COLUMNS (default 8) print
+     columns.  *Note Tabs::.
+
+'--suppress-blank-empty'
+     Suppress any blanks before newlines when printing the
+     representation of an empty line, when outputting normal, context,
+     or unified format.  *Note Trailing Blanks::.
+
+'--to-file=FILE'
+     Compare each operand to FILE; FILE may be a directory.
+
+'-u'
+     Use the unified output format, showing three lines of context.
+     *Note Unified Format::.
+
+'--unchanged-group-format=FORMAT'
+     Use FORMAT to output a group of common lines taken from both files
+     in if-then-else format.  *Note Line Group Formats::.
+
+'--unchanged-line-format=FORMAT'
+     Use FORMAT to output a line common to both files in if-then-else
+     format.  *Note Line Formats::.
+
+'--unidirectional-new-file'
+     If a first file is missing, treat it as present but empty.  *Note
+     Comparing Directories::.
+
+'-U LINES'
+'--unified[=LINES]'
+     Use the unified output format, showing LINES (an integer) lines of
+     context, or three if LINES is not given.  *Note Unified Format::.
+     For proper operation, 'patch' typically needs at least two lines of
+     context.
+
+     On older systems, 'diff' supports an obsolete option '-LINES' that
+     has effect when combined with '-u'.  POSIX 1003.1-2001 (*note
+     Standards conformance::) does not allow this; use '-U LINES'
+     instead.
+
+'-v'
+'--version'
+     Output version information and then exit.
+
+'-w'
+'--ignore-all-space'
+     Ignore white space when comparing lines.  *Note White Space::.
+
+'-W COLUMNS'
+'--width=COLUMNS'
+     Output at most COLUMNS (default 130) print columns per line in side
+     by side format.  *Note Side by Side Format::.
+
+'-x PATTERN'
+'--exclude=PATTERN'
+     When comparing directories, ignore files and subdirectories whose
+     basenames match PATTERN.  *Note Comparing Directories::.
+
+'-X FILE'
+'--exclude-from=FILE'
+     When comparing directories, ignore files and subdirectories whose
+     basenames match any pattern contained in FILE.  *Note Comparing
+     Directories::.
+
+'-y'
+'--side-by-side'
+     Use the side by side output format.  *Note Side by Side Format::.
+
+'-Z'
+'--ignore-trailing-space'
+     Ignore white space at line end.  *Note White Space::.
+
+
+File: diffutils.info-t,  Node: Invoking diff3,  Next: Invoking patch,  Prev: Invoking diff,  Up: Top
+
+14 Invoking 'diff3'
+*******************
+
+The 'diff3' command compares three files and outputs descriptions of
+their differences.  Its arguments are as follows:
+
+     diff3 OPTIONS... MINE OLDER YOURS
+
+   The files to compare are MINE, OLDER, and YOURS.  At most one of
+these three file names may be '-', which tells 'diff3' to read the
+standard input for that file.
+
+   An exit status of 0 means 'diff3' was successful, 1 means some
+conflicts were found, and 2 means trouble.
+
+* Menu:
+
+* diff3 Options:: Summary of options to 'diff3'.
+
+
+File: diffutils.info-t,  Node: diff3 Options,  Up: Invoking diff3
+
+14.1 Options to 'diff3'
+=======================
+
+Below is a summary of all of the options that GNU 'diff3' accepts.
+Multiple single letter options (unless they take an argument) can be
+combined into a single command line argument.
+
+'-a'
+'--text'
+     Treat all files as text and compare them line-by-line, even if they
+     do not appear to be text.  *Note Binary::.
+
+'-A'
+'--show-all'
+     Incorporate all unmerged changes from OLDER to YOURS into MINE,
+     surrounding conflicts with bracket lines.  *Note Marking
+     Conflicts::.
+
+'--diff-program=PROGRAM'
+     Use the compatible comparison program PROGRAM to compare files
+     instead of 'diff'.
+
+'-e'
+'--ed'
+     Generate an 'ed' script that incorporates all the changes from
+     OLDER to YOURS into MINE.  *Note Which Changes::.
+
+'-E'
+'--show-overlap'
+     Like '-e', except bracket lines from overlapping changes' first and
+     third files.  *Note Marking Conflicts::.  With '-E', an overlapping
+     change looks like this:
+
+          <<<<<<< MINE
+          lines from MINE
+          =======
+          lines from YOURS
+          >>>>>>> YOURS
+
+'--help'
+     Output a summary of usage and then exit.
+
+'-i'
+     Generate 'w' and 'q' commands at the end of the 'ed' script for
+     System V compatibility.  This option must be combined with one of
+     the '-AeExX3' options, and may not be combined with '-m'.  *Note
+     Saving the Changed File::.
+
+'--label=LABEL'
+     Use the label LABEL for the brackets output by the '-A', '-E' and
+     '-X' options.  This option may be given up to three times, one for
+     each input file.  The default labels are the names of the input
+     files.  Thus 'diff3 --label X --label Y --label Z -m A B C' acts
+     like 'diff3 -m A B C', except that the output looks like it came
+     from files named 'X', 'Y' and 'Z' rather than from files named 'A',
+     'B' and 'C'.  *Note Marking Conflicts::.
+
+'-m'
+'--merge'
+     Apply the edit script to the first file and send the result to
+     standard output.  Unlike piping the output from 'diff3' to 'ed',
+     this works even for binary files and incomplete lines.  '-A' is
+     assumed if no edit script option is specified.  *Note Bypassing
+     ed::.
+
+'--strip-trailing-cr'
+     Strip any trailing carriage return at the end of an input line.
+     *Note Binary::.
+
+'-T'
+'--initial-tab'
+     Output a tab rather than two spaces before the text of a line in
+     normal format.  This causes the alignment of tabs in the line to
+     look normal.  *Note Tabs::.
+
+'-v'
+'--version'
+     Output version information and then exit.
+
+'-x'
+'--overlap-only'
+     Like '-e', except output only the overlapping changes.  *Note Which
+     Changes::.
+
+'-X'
+     Like '-E', except output only the overlapping changes.  In other
+     words, like '-x', except bracket changes as in '-E'.  *Note Marking
+     Conflicts::.
+
+'-3'
+'--easy-only'
+     Like '-e', except output only the nonoverlapping changes.  *Note
+     Which Changes::.
+
+
+File: diffutils.info-t,  Node: Invoking patch,  Next: Invoking sdiff,  Prev: Invoking diff3,  Up: Top
+
+15 Invoking 'patch'
+*******************
+
+Normally 'patch' is invoked like this:
+
+     patch <PATCHFILE
+
+   The full format for invoking 'patch' is:
+
+     patch OPTIONS... [ORIGFILE [PATCHFILE]]
+
+   You can also specify where to read the patch from with the '-i
+PATCHFILE' or '--input=PATCHFILE' option.  If you do not specify
+PATCHFILE, or if PATCHFILE is '-', 'patch' reads the patch (that is, the
+'diff' output) from the standard input.
+
+   If you do not specify an input file on the command line, 'patch'
+tries to intuit from the "leading text" (any text in the patch that
+comes before the 'diff' output) which file to edit.  *Note Multiple
+Patches::.
+
+   By default, 'patch' replaces the original input file with the patched
+version, possibly after renaming the original file into a backup file
+(*note Backup Names::, for a description of how 'patch' names backup
+files).  You can also specify where to put the output with the '-o FILE'
+or '--output=FILE' option; however, do not use this option if FILE is
+one of the input files.
+
+* Menu:
+
+* patch Options::     Summary table of options to 'patch'.
+
+
+File: diffutils.info-t,  Node: patch Options,  Up: Invoking patch
+
+15.1 Options to 'patch'
+=======================
+
+Here is a summary of all of the options that GNU 'patch' accepts.  *Note
+patch and Tradition::, for which of these options are safe to use in
+older versions of 'patch'.
+
+   Multiple single-letter options that do not take an argument can be
+combined into a single command line argument with only one dash.
+
+'-b'
+'--backup'
+     Back up the original contents of each file, even if backups would
+     normally not be made.  *Note Backups::.
+
+'-B PREFIX'
+'--prefix=PREFIX'
+     Prepend PREFIX to backup file names.  *Note Backup Names::.
+
+'--backup-if-mismatch'
+     Back up the original contents of each file if the patch does not
+     exactly match the file.  This is the default behavior when not
+     conforming to POSIX.  *Note Backups::.
+
+'--binary'
+     Read and write all files in binary mode, except for standard output
+     and '/dev/tty'.  This option has no effect on POSIX-conforming
+     systems like GNU/Linux.  On systems where this option makes a
+     difference, the patch should be generated by 'diff -a --binary'.
+     *Note Binary::.
+
+'-c'
+'--context'
+     Interpret the patch file as a context diff.  *Note patch Input::.
+
+'-d DIRECTORY'
+'--directory=DIRECTORY'
+     Make directory DIRECTORY the current directory for interpreting
+     both file names in the patch file, and file names given as
+     arguments to other options.  *Note patch Directories::.
+
+'-D NAME'
+'--ifdef=NAME'
+     Make merged if-then-else output using NAME.  *Note If-then-else::.
+
+'--dry-run'
+     Print the results of applying the patches without actually changing
+     any files.  *Note Dry Runs::.
+
+'-e'
+'--ed'
+     Interpret the patch file as an 'ed' script.  *Note patch Input::.
+
+'-E'
+'--remove-empty-files'
+     Remove output files that are empty after the patches have been
+     applied.  *Note Creating and Removing::.
+
+'-f'
+'--force'
+     Assume that the user knows exactly what he or she is doing, and do
+     not ask any questions.  *Note patch Messages::.
+
+'-F LINES'
+'--fuzz=LINES'
+     Set the maximum fuzz factor to LINES.  *Note Inexact::.
+
+'-g NUM'
+'--get=NUM'
+     If NUM is positive, get input files from a revision control system
+     as necessary; if zero, do not get the files; if negative, ask the
+     user whether to get the files.  *Note Revision Control::.
+
+'--help'
+     Output a summary of usage and then exit.
+
+'-i PATCHFILE'
+'--input=PATCHFILE'
+     Read the patch from PATCHFILE rather than from standard input.
+     *Note patch Options::.
+
+'-l'
+'--ignore-white-space'
+     Let any sequence of blanks (spaces or tabs) in the patch file match
+     any sequence of blanks in the input file.  *Note Changed White
+     Space::.
+
+'-n'
+'--normal'
+     Interpret the patch file as a normal diff.  *Note patch Input::.
+
+'-N'
+'--forward'
+     Ignore patches that 'patch' thinks are reversed or already applied.
+     See also '-R'.  *Note Reversed Patches::.
+
+'--no-backup-if-mismatch'
+     Do not back up the original contents of files.  This is the default
+     behavior when conforming to POSIX.  *Note Backups::.
+
+'-o FILE'
+'--output=FILE'
+     Use FILE as the output file name.  *Note patch Options::.
+
+'-pNUMBER'
+'--strip=NUMBER'
+     Set the file name strip count to NUMBER.  *Note patch
+     Directories::.
+
+'--posix'
+     Conform to POSIX, as if the 'POSIXLY_CORRECT' environment variable
+     had been set.  *Note patch and POSIX::.
+
+'--quoting-style=WORD'
+     Use style WORD to quote names in diagnostics, as if the
+     'QUOTING_STYLE' environment variable had been set to WORD.  *Note
+     patch Quoting Style::.
+
+'-r REJECT-FILE'
+'--reject-file=REJECT-FILE'
+     Use REJECT-FILE as the reject file name.  *Note Reject Names::.
+
+'-R'
+'--reverse'
+     Assume that this patch was created with the old and new files
+     swapped.  *Note Reversed Patches::.
+
+'-s'
+'--quiet'
+'--silent'
+     Work silently unless an error occurs.  *Note patch Messages::.
+
+'-t'
+'--batch'
+     Do not ask any questions.  *Note patch Messages::.
+
+'-T'
+'--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.  *Note Patching Time Stamps::.
+
+'-u'
+'--unified'
+     Interpret the patch file as a unified diff.  *Note patch Input::.
+
+'-v'
+'--version'
+     Output version information and then exit.
+
+'-V BACKUP-STYLE'
+'--version=control=BACKUP-STYLE'
+     Select the naming convention for backup file names.  *Note Backup
+     Names::.
+
+'--verbose'
+     Print more diagnostics than usual.  *Note patch Messages::.
+
+'-x NUMBER'
+'--debug=NUMBER'
+     Set internal debugging flags.  Of interest only to 'patch'
+     patchers.
+
+'-Y PREFIX'
+'--basename-prefix=PREFIX'
+     Prepend PREFIX to base names of backup files.  *Note Backup
+     Names::.
+
+'-z SUFFIX'
+'--suffix=SUFFIX'
+     Use SUFFIX as the backup extension instead of '.orig' or '~'.
+     *Note Backup Names::.
+
+'-Z'
+'--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 UTC.  *Note Patching Time Stamps::.
+
+
+File: diffutils.info-t,  Node: Invoking sdiff,  Next: Standards conformance,  Prev: Invoking patch,  Up: Top
+
+16 Invoking 'sdiff'
+*******************
+
+The 'sdiff' command merges two files and interactively outputs the
+results.  Its arguments are as follows:
+
+     sdiff -o OUTFILE OPTIONS... FROM-FILE TO-FILE
+
+   This merges FROM-FILE with TO-FILE, with output to OUTFILE.  If
+FROM-FILE is a directory and TO-FILE is not, 'sdiff' compares the file
+in FROM-FILE whose file name is that of TO-FILE, and vice versa.
+FROM-FILE and TO-FILE may not both be directories.
+
+   'sdiff' options begin with '-', so normally FROM-FILE and TO-FILE may
+not begin with '-'.  However, '--' as an argument by itself treats the
+remaining arguments as file names even if they begin with '-'.  You may
+not use '-' as an input file.
+
+   'sdiff' without '--output' ('-o') produces a side-by-side difference.
+This usage is obsolete; use the '--side-by-side' ('-y') option of 'diff'
+instead.
+
+   An exit status of 0 means no differences were found, 1 means some
+differences were found, and 2 means trouble.
+
+* Menu:
+
+* sdiff Options:: Summary of options to 'diff'.
+
+
+File: diffutils.info-t,  Node: sdiff Options,  Up: Invoking sdiff
+
+16.1 Options to 'sdiff'
+=======================
+
+Below is a summary of all of the options that GNU 'sdiff' accepts.  Each
+option has two equivalent names, one of which is a single letter
+preceded by '-', and the other of which is a long name preceded by '--'.
+Multiple single letter options (unless they take an argument) can be
+combined into a single command line argument.  Long named options can be
+abbreviated to any unique prefix of their name.
+
+'-a'
+'--text'
+     Treat all files as text and compare them line-by-line, even if they
+     do not appear to be text.  *Note Binary::.
+
+'-b'
+'--ignore-space-change'
+     Ignore changes in amount of white space.  *Note White Space::.
+
+'-B'
+'--ignore-blank-lines'
+     Ignore changes that just insert or delete blank lines.  *Note Blank
+     Lines::.
+
+'-d'
+'--minimal'
+     Change the algorithm to perhaps find a smaller set of changes.
+     This makes 'sdiff' slower (sometimes much slower).  *Note diff
+     Performance::.
+
+'--diff-program=PROGRAM'
+     Use the compatible comparison program PROGRAM to compare files
+     instead of 'diff'.
+
+'-E'
+'--ignore-tab-expansion'
+     Ignore changes due to tab expansion.  *Note White Space::.
+
+'--help'
+     Output a summary of usage and then exit.
+
+'-i'
+'--ignore-case'
+     Ignore changes in case; consider upper- and lower-case to be the
+     same.  *Note Case Folding::.
+
+'-I REGEXP'
+'--ignore-matching-lines=REGEXP'
+     Ignore changes that just insert or delete lines that match REGEXP.
+     *Note Specified Lines::.
+
+'-l'
+'--left-column'
+     Print only the left column of two common lines.  *Note Side by Side
+     Format::.
+
+'-o FILE'
+'--output=FILE'
+     Put merged output into FILE.  This option is required for merging.
+
+'-s'
+'--suppress-common-lines'
+     Do not print common lines.  *Note Side by Side Format::.
+
+'--speed-large-files'
+     Use heuristics to speed handling of large files that have numerous
+     scattered small changes.  *Note diff Performance::.
+
+'--strip-trailing-cr'
+     Strip any trailing carriage return at the end of an input line.
+     *Note Binary::.
+
+'-t'
+'--expand-tabs'
+     Expand tabs to spaces in the output, to preserve the alignment of
+     tabs in the input files.  *Note Tabs::.
+
+'--tabsize=COLUMNS'
+     Assume that tab stops are set every COLUMNS (default 8) print
+     columns.  *Note Tabs::.
+
+'-v'
+'--version'
+     Output version information and then exit.
+
+'-w COLUMNS'
+'--width=COLUMNS'
+     Output at most COLUMNS (default 130) print columns per line.  *Note
+     Side by Side Format::.  Note that for historical reasons, this
+     option is '-W' in 'diff', '-w' in 'sdiff'.
+
+'-W'
+'--ignore-all-space'
+     Ignore white space when comparing lines.  *Note White Space::.
+     Note that for historical reasons, this option is '-w' in 'diff',
+     '-W' in 'sdiff'.
+
+'-Z'
+'--ignore-trailing-space'
+     Ignore white space at line end.  *Note White Space::.
+
+
+File: diffutils.info-t,  Node: Standards conformance,  Next: Projects,  Prev: Invoking sdiff,  Up: Top
+
+17 Standards conformance
+************************
+
+In a few cases, the GNU utilities' default behavior is incompatible with
+the POSIX standard.  To suppress these incompatibilities, define the
+'POSIXLY_CORRECT' environment variable.  Unless you are checking for
+POSIX conformance, you probably do not need to define 'POSIXLY_CORRECT'.
+
+   Normally options and operands can appear in any order, and programs
+act as if all the options appear before any operands.  For example,
+'diff lao tzu -C 2' acts like 'diff -C 2 lao tzu', since '2' is an
+option-argument of '-C'.  However, if the 'POSIXLY_CORRECT' environment
+variable is set, options must appear before operands, unless otherwise
+specified for a particular command.
+
+   Newer versions of POSIX are occasionally incompatible with older
+versions.  For example, older versions of POSIX allowed the command
+'diff -c -10' to have the same meaning as 'diff -C 10', but POSIX
+1003.1-2001 'diff' no longer allows digit-string options like '-10'.
+
+   The GNU utilities normally conform to the version of POSIX that is
+standard for your system.  To cause them to conform to a different
+version of POSIX, define the '_POSIX2_VERSION' environment variable to a
+value of the form YYYYMM specifying the year and month the standard was
+adopted.  Two values are currently supported for '_POSIX2_VERSION':
+'199209' stands for POSIX 1003.2-1992, and '200112' stands for POSIX
+1003.1-2001.  For example, if you are running older software that
+assumes an older version of POSIX and uses 'diff -c -10', you can work
+around the compatibility problems by setting '_POSIX2_VERSION=199209' in
+your environment.
+
+
+File: diffutils.info-t,  Node: Projects,  Next: Copying This Manual,  Prev: Standards conformance,  Up: Top
+
+18 Future Projects
+******************
+
+Here are some ideas for improving GNU 'diff' and 'patch'.  The GNU
+project has identified some improvements as potential programming
+projects for volunteers.  You can also help by reporting any bugs that
+you find.
+
+   If you are a programmer and would like to contribute something to the
+GNU project, please consider volunteering for one of these projects.  If
+you are seriously contemplating work, please write to <gvc@gnu.org> to
+coordinate with other volunteers.
+
+* Menu:
+
+* Shortcomings:: Suggested projects for improvements.
+* Bugs::         Reporting bugs.
+
+
+File: diffutils.info-t,  Node: Shortcomings,  Next: Bugs,  Up: Projects
+
+18.1 Suggested Projects for Improving GNU 'diff' and 'patch'
+============================================================
+
+One should be able to use GNU 'diff' to generate a patch from any pair
+of directory trees, and given the patch and a copy of one such tree, use
+'patch' to generate a faithful copy of the other.  Unfortunately, some
+changes to directory trees cannot be expressed using current patch
+formats; also, 'patch' does not handle some of the existing formats.
+These shortcomings motivate the following suggested projects.
+
+* Menu:
+
+* Internationalization:: Handling multibyte and varying-width characters.
+* Changing Structure::   Handling changes to the directory structure.
+* Special Files::        Handling symbolic links, device special files, etc.
+* Unusual File Names::   Handling file names that contain unusual characters.
+* Time Stamp Order::     Outputting diffs in time stamp order.
+* Ignoring Changes::     Ignoring certain changes while showing others.
+* Speedups::             Improving performance.
+
+
+File: diffutils.info-t,  Node: Internationalization,  Next: Changing Structure,  Up: Shortcomings
+
+18.1.1 Handling Multibyte and Varying-Width Characters
+------------------------------------------------------
+
+'diff', 'diff3' and 'sdiff' treat each line of input as a string of
+unibyte characters.  This can mishandle multibyte characters in some
+cases.  For example, when asked to ignore spaces, 'diff' does not
+properly ignore a multibyte space character.
+
+   Also, 'diff' currently assumes that each byte is one column wide, and
+this assumption is incorrect in some locales, e.g., locales that use
+UTF-8 encoding.  This causes problems with the '-y' or '--side-by-side'
+option of 'diff'.
+
+   These problems need to be fixed without unduly affecting the
+performance of the utilities in unibyte environments.
+
+   The IBM GNU/Linux Technology Center Internationalization Team has
+proposed patches to support internationalized 'diff'
+(http://oss.software.ibm.com/developer/opensource/linux/patches/i18n/diffutils-2.7.2-i18n-0.1.patch.gz).
+Unfortunately, these patches are incomplete and are to an older version
+of 'diff', so more work needs to be done in this area.
+
+
+File: diffutils.info-t,  Node: Changing Structure,  Next: Special Files,  Prev: Internationalization,  Up: Shortcomings
+
+18.1.2 Handling Changes to the Directory Structure
+--------------------------------------------------
+
+'diff' and 'patch' do not handle some changes to directory structure.
+For example, suppose one directory tree contains a directory named 'D'
+with some subsidiary files, and another contains a file with the same
+name 'D'.  'diff -r' does not output enough information for 'patch' to
+transform the directory subtree into the file.
+
+   There should be a way to specify that a file has been removed without
+having to include its entire contents in the patch file.  There should
+also be a way to tell 'patch' that a file was renamed, even if there is
+no way for 'diff' to generate such information.  There should be a way
+to tell 'patch' that a file's time stamp has changed, even if its
+contents have not changed.
+
+   These problems can be fixed by extending the 'diff' output format to
+represent changes in directory structure, and extending 'patch' to
+understand these extensions.
+
+
+File: diffutils.info-t,  Node: Special Files,  Next: Unusual File Names,  Prev: Changing Structure,  Up: Shortcomings
+
+18.1.3 Files that are Neither Directories Nor Regular Files
+-----------------------------------------------------------
+
+Some files are neither directories nor regular files: they are unusual
+files like symbolic links, device special files, named pipes, and
+sockets.  Currently, 'diff' treats symbolic links as if they were the
+pointed-to files, except that a recursive 'diff' reports an error if it
+detects infinite loops of symbolic links (e.g., symbolic links to '..').
+'diff' treats other special files like regular files if they are
+specified at the top level, but simply reports their presence when
+comparing directories.  This means that 'patch' cannot represent changes
+to such files.  For example, if you change which file a symbolic link
+points to, 'diff' outputs the difference between the two files, instead
+of the change to the symbolic link.
+
+   'diff' should optionally report changes to special files specially,
+and 'patch' should be extended to understand these extensions.
+
+
+File: diffutils.info-t,  Node: Unusual File Names,  Next: Time Stamp Order,  Prev: Special Files,  Up: Shortcomings
+
+18.1.4 File Names that Contain Unusual Characters
+-------------------------------------------------
+
+When a file name contains an unusual character like a newline or white
+space, 'diff -r' generates a patch that 'patch' cannot parse.  The
+problem is with format of 'diff' output, not just with 'patch', because
+with odd enough file names one can cause 'diff' to generate a patch that
+is syntactically correct but patches the wrong files.  The format of
+'diff' output should be extended to handle all possible file names.
+
+
+File: diffutils.info-t,  Node: Time Stamp Order,  Next: Ignoring Changes,  Prev: Unusual File Names,  Up: Shortcomings
+
+18.1.5 Outputting Diffs in Time Stamp Order
+-------------------------------------------
+
+Applying 'patch' to a multiple-file diff can result in files whose time
+stamps are out of order.  GNU 'patch' has options to restore the time
+stamps of the updated files (*note Patching Time Stamps::), but
+sometimes it is useful to generate a patch that works even if the
+recipient does not have GNU patch, or does not use these options.  One
+way to do this would be to implement a 'diff' option to output diffs in
+time stamp order.
+
+
+File: diffutils.info-t,  Node: Ignoring Changes,  Next: Speedups,  Prev: Time Stamp Order,  Up: Shortcomings
+
+18.1.6 Ignoring Certain Changes
+-------------------------------
+
+It would be nice to have a feature for specifying two strings, one in
+FROM-FILE and one in TO-FILE, which should be considered to match.
+Thus, if the two strings are 'foo' and 'bar', then if two lines differ
+only in that 'foo' in file 1 corresponds to 'bar' in file 2, the lines
+are treated as identical.
+
+   It is not clear how general this feature can or should be, or what
+syntax should be used for it.
+
+   A partial substitute is to filter one or both files before comparing,
+e.g.:
+
+     sed 's/foo/bar/g' file1 | diff - file2
+
+   However, this outputs the filtered text, not the original.
+
+
+File: diffutils.info-t,  Node: Speedups,  Prev: Ignoring Changes,  Up: Shortcomings
+
+18.1.7 Improving Performance
+----------------------------
+
+When comparing two large directory structures, one of which was
+originally copied from the other with time stamps preserved (e.g., with
+'cp -pR'), it would greatly improve performance if an option told 'diff'
+to assume that two files with the same size and time stamps have the
+same content.  *Note diff Performance::.
+
+
+File: diffutils.info-t,  Node: Bugs,  Prev: Shortcomings,  Up: Projects
+
+18.2 Reporting Bugs
+===================
+
+If you think you have found a bug in GNU 'cmp', 'diff', 'diff3', or
+'sdiff', please report it by electronic mail to the GNU utilities bug
+report mailing list (http://mail.gnu.org/mailman/listinfo/bug-diffutils)
+<bug-diffutils@gnu.org>.  Please send bug reports for GNU 'patch' to
+<bug-patch@gnu.org>.  Send as precise a description of the problem as
+you can, including the output of the '--version' option and sample input
+files that produce the bug, if applicable.  If you have a nontrivial fix
+for the bug, please send it as well.  If you have a patch, please send
+it too.  It may simplify the maintainer's job if the patch is relative
+to a recent test release, which you can find in the directory
+<ftp://alpha.gnu.org/gnu/diffutils/>.
+
+
+File: diffutils.info-t,  Node: Copying This Manual,  Next: Translations,  Prev: Projects,  Up: Top
+
+Appendix A Copying This Manual
+******************************
+
+                     Version 1.3, 3 November 2008
+
+     Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
+     <http://fsf.org/>
+
+     Everyone is permitted to copy and distribute verbatim copies
+     of this license document, but changing it is not allowed.
+
+  0. PREAMBLE
+
+     The purpose of this License is to make a manual, textbook, or other
+     functional and useful document "free" in the sense of freedom: to
+     assure everyone the effective freedom to copy and redistribute it,
+     with or without modifying it, either commercially or
+     noncommercially.  Secondarily, this License preserves for the
+     author and publisher a way to get credit for their work, while not
+     being considered responsible for modifications made by others.
+
+     This License is a kind of "copyleft", which means that derivative
+     works of the document must themselves be free in the same sense.
+     It complements the GNU General Public License, which is a copyleft
+     license designed for free software.
+
+     We have designed this License in order to use it for manuals for
+     free software, because free software needs free documentation: a
+     free program should come with manuals providing the same freedoms
+     that the software does.  But this License is not limited to
+     software manuals; it can be used for any textual work, regardless
+     of subject matter or whether it is published as a printed book.  We
+     recommend this License principally for works whose purpose is
+     instruction or reference.
+
+  1. APPLICABILITY AND DEFINITIONS
+
+     This License applies to any manual or other work, in any medium,
+     that contains a notice placed by the copyright holder saying it can
+     be distributed under the terms of this License.  Such a notice
+     grants a world-wide, royalty-free license, unlimited in duration,
+     to use that work under the conditions stated herein.  The
+     "Document", below, refers to any such manual or work.  Any member
+     of the public is a licensee, and is addressed as "you".  You accept
+     the license if you copy, modify or distribute the work in a way
+     requiring permission under copyright law.
+
+     A "Modified Version" of the Document means any work containing the
+     Document or a portion of it, either copied verbatim, or with
+     modifications and/or translated into another language.
+
+     A "Secondary Section" is a named appendix or a front-matter section
+     of the Document that deals exclusively with the relationship of the
+     publishers or authors of the Document to the Document's overall
+     subject (or to related matters) and contains nothing that could
+     fall directly within that overall subject.  (Thus, if the Document
+     is in part a textbook of mathematics, a Secondary Section may not
+     explain any mathematics.)  The relationship could be a matter of
+     historical connection with the subject or with related matters, or
+     of legal, commercial, philosophical, ethical or political position
+     regarding them.
+
+     The "Invariant Sections" are certain Secondary Sections whose
+     titles are designated, as being those of Invariant Sections, in the
+     notice that says that the Document is released under this License.
+     If a section does not fit the above definition of Secondary then it
+     is not allowed to be designated as Invariant.  The Document may
+     contain zero Invariant Sections.  If the Document does not identify
+     any Invariant Sections then there are none.
+
+     The "Cover Texts" are certain short passages of text that are
+     listed, as Front-Cover Texts or Back-Cover Texts, in the notice
+     that says that the Document is released under this License.  A
+     Front-Cover Text may be at most 5 words, and a Back-Cover Text may
+     be at most 25 words.
+
+     A "Transparent" copy of the Document means a machine-readable copy,
+     represented in a format whose specification is available to the
+     general public, that is suitable for revising the document
+     straightforwardly with generic text editors or (for images composed
+     of pixels) generic paint programs or (for drawings) some widely
+     available drawing editor, and that is suitable for input to text
+     formatters or for automatic translation to a variety of formats
+     suitable for input to text formatters.  A copy made in an otherwise
+     Transparent file format whose markup, or absence of markup, has
+     been arranged to thwart or discourage subsequent modification by
+     readers is not Transparent.  An image format is not Transparent if
+     used for any substantial amount of text.  A copy that is not
+     "Transparent" is called "Opaque".
+
+     Examples of suitable formats for Transparent copies include plain
+     ASCII without markup, Texinfo input format, LaTeX input format,
+     SGML or XML using a publicly available DTD, and standard-conforming
+     simple HTML, PostScript or PDF designed for human modification.
+     Examples of transparent image formats include PNG, XCF and JPG.
+     Opaque formats include proprietary formats that can be read and
+     edited only by proprietary word processors, SGML or XML for which
+     the DTD and/or processing tools are not generally available, and
+     the machine-generated HTML, PostScript or PDF produced by some word
+     processors for output purposes only.
+
+     The "Title Page" means, for a printed book, the title page itself,
+     plus such following pages as are needed to hold, legibly, the
+     material this License requires to appear in the title page.  For
+     works in formats which do not have any title page as such, "Title
+     Page" means the text near the most prominent appearance of the
+     work's title, preceding the beginning of the body of the text.
+
+     The "publisher" means any person or entity that distributes copies
+     of the Document to the public.
+
+     A section "Entitled XYZ" means a named subunit of the Document
+     whose title either is precisely XYZ or contains XYZ in parentheses
+     following text that translates XYZ in another language.  (Here XYZ
+     stands for a specific section name mentioned below, such as
+     "Acknowledgements", "Dedications", "Endorsements", or "History".)
+     To "Preserve the Title" of such a section when you modify the
+     Document means that it remains a section "Entitled XYZ" according
+     to this definition.
+
+     The Document may include Warranty Disclaimers next to the notice
+     which states that this License applies to the Document.  These
+     Warranty Disclaimers are considered to be included by reference in
+     this License, but only as regards disclaiming warranties: any other
+     implication that these Warranty Disclaimers may have is void and
+     has no effect on the meaning of this License.
+
+  2. VERBATIM COPYING
+
+     You may copy and distribute the Document in any medium, either
+     commercially or noncommercially, provided that this License, the
+     copyright notices, and the license notice saying this License
+     applies to the Document are reproduced in all copies, and that you
+     add no other conditions whatsoever to those of this License.  You
+     may not use technical measures to obstruct or control the reading
+     or further copying of the copies you make or distribute.  However,
+     you may accept compensation in exchange for copies.  If you
+     distribute a large enough number of copies you must also follow the
+     conditions in section 3.
+
+     You may also lend copies, under the same conditions stated above,
+     and you may publicly display copies.
+
+  3. COPYING IN QUANTITY
+
+     If you publish printed copies (or copies in media that commonly
+     have printed covers) of the Document, numbering more than 100, and
+     the Document's license notice requires Cover Texts, you must
+     enclose the copies in covers that carry, clearly and legibly, all
+     these Cover Texts: Front-Cover Texts on the front cover, and
+     Back-Cover Texts on the back cover.  Both covers must also clearly
+     and legibly identify you as the publisher of these copies.  The
+     front cover must present the full title with all words of the title
+     equally prominent and visible.  You may add other material on the
+     covers in addition.  Copying with changes limited to the covers, as
+     long as they preserve the title of the Document and satisfy these
+     conditions, can be treated as verbatim copying in other respects.
+
+     If the required texts for either cover are too voluminous to fit
+     legibly, you should put the first ones listed (as many as fit
+     reasonably) on the actual cover, and continue the rest onto
+     adjacent pages.
+
+     If you publish or distribute Opaque copies of the Document
+     numbering more than 100, you must either include a machine-readable
+     Transparent copy along with each Opaque copy, or state in or with
+     each Opaque copy a computer-network location from which the general
+     network-using public has access to download using public-standard
+     network protocols a complete Transparent copy of the Document, free
+     of added material.  If you use the latter option, you must take
+     reasonably prudent steps, when you begin distribution of Opaque
+     copies in quantity, to ensure that this Transparent copy will
+     remain thus accessible at the stated location until at least one
+     year after the last time you distribute an Opaque copy (directly or
+     through your agents or retailers) of that edition to the public.
+
+     It is requested, but not required, that you contact the authors of
+     the Document well before redistributing any large number of copies,
+     to give them a chance to provide you with an updated version of the
+     Document.
+
+  4. MODIFICATIONS
+
+     You may copy and distribute a Modified Version of the Document
+     under the conditions of sections 2 and 3 above, provided that you
+     release the Modified Version under precisely this License, with the
+     Modified Version filling the role of the Document, thus licensing
+     distribution and modification of the Modified Version to whoever
+     possesses a copy of it.  In addition, you must do these things in
+     the Modified Version:
+
+       A. Use in the Title Page (and on the covers, if any) a title
+          distinct from that of the Document, and from those of previous
+          versions (which should, if there were any, be listed in the
+          History section of the Document).  You may use the same title
+          as a previous version if the original publisher of that
+          version gives permission.
+
+       B. List on the Title Page, as authors, one or more persons or
+          entities responsible for authorship of the modifications in
+          the Modified Version, together with at least five of the
+          principal authors of the Document (all of its principal
+          authors, if it has fewer than five), unless they release you
+          from this requirement.
+
+       C. State on the Title page the name of the publisher of the
+          Modified Version, as the publisher.
+
+       D. Preserve all the copyright notices of the Document.
+
+       E. Add an appropriate copyright notice for your modifications
+          adjacent to the other copyright notices.
+
+       F. Include, immediately after the copyright notices, a license
+          notice giving the public permission to use the Modified
+          Version under the terms of this License, in the form shown in
+          the Addendum below.
+
+       G. Preserve in that license notice the full lists of Invariant
+          Sections and required Cover Texts given in the Document's
+          license notice.
+
+       H. Include an unaltered copy of this License.
+
+       I. Preserve the section Entitled "History", Preserve its Title,
+          and add to it an item stating at least the title, year, new
+          authors, and publisher of the Modified Version as given on the
+          Title Page.  If there is no section Entitled "History" in the
+          Document, create one stating the title, year, authors, and
+          publisher of the Document as given on its Title Page, then add
+          an item describing the Modified Version as stated in the
+          previous sentence.
+
+       J. Preserve the network location, if any, given in the Document
+          for public access to a Transparent copy of the Document, and
+          likewise the network locations given in the Document for
+          previous versions it was based on.  These may be placed in the
+          "History" section.  You may omit a network location for a work
+          that was published at least four years before the Document
+          itself, or if the original publisher of the version it refers
+          to gives permission.
+
+       K. For any section Entitled "Acknowledgements" or "Dedications",
+          Preserve the Title of the section, and preserve in the section
+          all the substance and tone of each of the contributor
+          acknowledgements and/or dedications given therein.
+
+       L. Preserve all the Invariant Sections of the Document, unaltered
+          in their text and in their titles.  Section numbers or the
+          equivalent are not considered part of the section titles.
+
+       M. Delete any section Entitled "Endorsements".  Such a section
+          may not be included in the Modified Version.
+
+       N. Do not retitle any existing section to be Entitled
+          "Endorsements" or to conflict in title with any Invariant
+          Section.
+
+       O. Preserve any Warranty Disclaimers.
+
+     If the Modified Version includes new front-matter sections or
+     appendices that qualify as Secondary Sections and contain no
+     material copied from the Document, you may at your option designate
+     some or all of these sections as invariant.  To do this, add their
+     titles to the list of Invariant Sections in the Modified Version's
+     license notice.  These titles must be distinct from any other
+     section titles.
+
+     You may add a section Entitled "Endorsements", provided it contains
+     nothing but endorsements of your Modified Version by various
+     parties--for example, statements of peer review or that the text
+     has been approved by an organization as the authoritative
+     definition of a standard.
+
+     You may add a passage of up to five words as a Front-Cover Text,
+     and a passage of up to 25 words as a Back-Cover Text, to the end of
+     the list of Cover Texts in the Modified Version.  Only one passage
+     of Front-Cover Text and one of Back-Cover Text may be added by (or
+     through arrangements made by) any one entity.  If the Document
+     already includes a cover text for the same cover, previously added
+     by you or by arrangement made by the same entity you are acting on
+     behalf of, you may not add another; but you may replace the old
+     one, on explicit permission from the previous publisher that added
+     the old one.
+
+     The author(s) and publisher(s) of the Document do not by this
+     License give permission to use their names for publicity for or to
+     assert or imply endorsement of any Modified Version.
+
+  5. COMBINING DOCUMENTS
+
+     You may combine the Document with other documents released under
+     this License, under the terms defined in section 4 above for
+     modified versions, provided that you include in the combination all
+     of the Invariant Sections of all of the original documents,
+     unmodified, and list them all as Invariant Sections of your
+     combined work in its license notice, and that you preserve all
+     their Warranty Disclaimers.
+
+     The combined work need only contain one copy of this License, and
+     multiple identical Invariant Sections may be replaced with a single
+     copy.  If there are multiple Invariant Sections with the same name
+     but different contents, make the title of each such section unique
+     by adding at the end of it, in parentheses, the name of the
+     original author or publisher of that section if known, or else a
+     unique number.  Make the same adjustment to the section titles in
+     the list of Invariant Sections in the license notice of the
+     combined work.
+
+     In the combination, you must combine any sections Entitled
+     "History" in the various original documents, forming one section
+     Entitled "History"; likewise combine any sections Entitled
+     "Acknowledgements", and any sections Entitled "Dedications".  You
+     must delete all sections Entitled "Endorsements."
+
+  6. COLLECTIONS OF DOCUMENTS
+
+     You may make a collection consisting of the Document and other
+     documents released under this License, and replace the individual
+     copies of this License in the various documents with a single copy
+     that is included in the collection, provided that you follow the
+     rules of this License for verbatim copying of each of the documents
+     in all other respects.
+
+     You may extract a single document from such a collection, and
+     distribute it individually under this License, provided you insert
+     a copy of this License into the extracted document, and follow this
+     License in all other respects regarding verbatim copying of that
+     document.
+
+  7. AGGREGATION WITH INDEPENDENT WORKS
+
+     A compilation of the Document or its derivatives with other
+     separate and independent documents or works, in or on a volume of a
+     storage or distribution medium, is called an "aggregate" if the
+     copyright resulting from the compilation is not used to limit the
+     legal rights of the compilation's users beyond what the individual
+     works permit.  When the Document is included in an aggregate, this
+     License does not apply to the other works in the aggregate which
+     are not themselves derivative works of the Document.
+
+     If the Cover Text requirement of section 3 is applicable to these
+     copies of the Document, then if the Document is less than one half
+     of the entire aggregate, the Document's Cover Texts may be placed
+     on covers that bracket the Document within the aggregate, or the
+     electronic equivalent of covers if the Document is in electronic
+     form.  Otherwise they must appear on printed covers that bracket
+     the whole aggregate.
+
+  8. TRANSLATION
+
+     Translation is considered a kind of modification, so you may
+     distribute translations of the Document under the terms of section
+     4.  Replacing Invariant Sections with translations requires special
+     permission from their copyright holders, but you may include
+     translations of some or all Invariant Sections in addition to the
+     original versions of these Invariant Sections.  You may include a
+     translation of this License, and all the license notices in the
+     Document, and any Warranty Disclaimers, provided that you also
+     include the original English version of this License and the
+     original versions of those notices and disclaimers.  In case of a
+     disagreement between the translation and the original version of
+     this License or a notice or disclaimer, the original version will
+     prevail.
+
+     If a section in the Document is Entitled "Acknowledgements",
+     "Dedications", or "History", the requirement (section 4) to
+     Preserve its Title (section 1) will typically require changing the
+     actual title.
+
+  9. TERMINATION
+
+     You may not copy, modify, sublicense, or distribute the Document
+     except as expressly provided under this License.  Any attempt
+     otherwise to copy, modify, sublicense, or distribute it is void,
+     and will automatically terminate your rights under this License.
+
+     However, if you cease all violation of this License, then your
+     license from a particular copyright holder is reinstated (a)
+     provisionally, unless and until the copyright holder explicitly and
+     finally terminates your license, and (b) permanently, if the
+     copyright holder fails to notify you of the violation by some
+     reasonable means prior to 60 days after the cessation.
+
+     Moreover, your license from a particular copyright holder is
+     reinstated permanently if the copyright holder notifies you of the
+     violation by some reasonable means, this is the first time you have
+     received notice of violation of this License (for any work) from
+     that copyright holder, and you cure the violation prior to 30 days
+     after your receipt of the notice.
+
+     Termination of your rights under this section does not terminate
+     the licenses of parties who have received copies or rights from you
+     under this License.  If your rights have been terminated and not
+     permanently reinstated, receipt of a copy of some or all of the
+     same material does not give you any rights to use it.
+
+  10. FUTURE REVISIONS OF THIS LICENSE
+
+     The Free Software Foundation may publish new, revised versions of
+     the GNU Free Documentation License from time to time.  Such new
+     versions will be similar in spirit to the present version, but may
+     differ in detail to address new problems or concerns.  See
+     <http://www.gnu.org/copyleft/>.
+
+     Each version of the License is given a distinguishing version
+     number.  If the Document specifies that a particular numbered
+     version of this License "or any later version" applies to it, you
+     have the option of following the terms and conditions either of
+     that specified version or of any later version that has been
+     published (not as a draft) by the Free Software Foundation.  If the
+     Document does not specify a version number of this License, you may
+     choose any version ever published (not as a draft) by the Free
+     Software Foundation.  If the Document specifies that a proxy can
+     decide which future versions of this License can be used, that
+     proxy's public statement of acceptance of a version permanently
+     authorizes you to choose that version for the Document.
+
+  11. RELICENSING
+
+     "Massive Multiauthor Collaboration Site" (or "MMC Site") means any
+     World Wide Web server that publishes copyrightable works and also
+     provides prominent facilities for anybody to edit those works.  A
+     public wiki that anybody can edit is an example of such a server.
+     A "Massive Multiauthor Collaboration" (or "MMC") contained in the
+     site means any set of copyrightable works thus published on the MMC
+     site.
+
+     "CC-BY-SA" means the Creative Commons Attribution-Share Alike 3.0
+     license published by Creative Commons Corporation, a not-for-profit
+     corporation with a principal place of business in San Francisco,
+     California, as well as future copyleft versions of that license
+     published by that same organization.
+
+     "Incorporate" means to publish or republish a Document, in whole or
+     in part, as part of another Document.
+
+     An MMC is "eligible for relicensing" if it is licensed under this
+     License, and if all works that were first published under this
+     License somewhere other than this MMC, and subsequently
+     incorporated in whole or in part into the MMC, (1) had no cover
+     texts or invariant sections, and (2) were thus incorporated prior
+     to November 1, 2008.
+
+     The operator of an MMC Site may republish an MMC contained in the
+     site under CC-BY-SA on the same site at any time before August 1,
+     2009, provided the MMC is eligible for relicensing.
+
+ADDENDUM: How to use this License for your documents
+====================================================
+
+To use this License in a document you have written, include a copy of
+the License in the document and put the following copyright and license
+notices just after the title page:
+
+       Copyright (C)  YEAR  YOUR NAME.
+       Permission is granted to copy, distribute and/or modify this document
+       under the terms of the GNU Free Documentation License, Version 1.3
+       or any later version published by the Free Software Foundation;
+       with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
+       Texts.  A copy of the license is included in the section entitled ``GNU
+       Free Documentation License''.
+
+   If you have Invariant Sections, Front-Cover Texts and Back-Cover
+Texts, replace the "with...Texts." line with this:
+
+         with the Invariant Sections being LIST THEIR TITLES, with
+         the Front-Cover Texts being LIST, and with the Back-Cover Texts
+         being LIST.
+
+   If you have Invariant Sections without Cover Texts, or some other
+combination of the three, merge those two alternatives to suit the
+situation.
+
+   If your document contains nontrivial examples of program code, we
+recommend releasing these examples in parallel under your choice of free
+software license, such as the GNU General Public License, to permit
+their use in free software.
+
+
+File: diffutils.info-t,  Node: Translations,  Next: Index,  Prev: Copying This Manual,  Up: Top
+
+Appendix B Translations of This Manual
+**************************************
+
+Nishio Futoshi of the GNUjdoc project has prepared a Japanese
+translation of this manual.  Its most recent version can be found at
+<http://openlab.ring.gr.jp/gnujdoc/cvsweb/cvsweb.cgi/gnujdoc/>.
+
+
+File: diffutils.info-t,  Node: Index,  Prev: Translations,  Up: Top
+
+Appendix C Index
+****************
+
+
+* Menu:
+
+* ! output format:                       Context.             (line   6)
+* +- output format:                      Unified Format.      (line   6)
+* < output format:                       Normal.              (line   6)
+* <<<<<<< for marking conflicts:         Marking Conflicts.   (line   6)
+* _POSIX2_VERSION:                       Standards conformance.
+                                                              (line  23)
+* ad capability:                         diff Options.        (line 179)
+* aligning tab stops:                    Tabs.                (line   6)
+* alternate file names:                  Alternate Names.     (line   6)
+* always color option:                   diff Options.        (line  43)
+* auto color option:                     diff Options.        (line  42)
+* backup file names:                     Backup Names.        (line   6)
+* backup file strategy:                  Backups.             (line   6)
+* binary file diff:                      Binary.              (line   6)
+* blank and tab difference suppression:  White Space.         (line   6)
+* blank line difference suppression:     Blank Lines.         (line   6)
+* brief difference reports:              Brief.               (line   6)
+* bug reports:                           Bugs.                (line   6)
+* C function headings:                   C Function Headings. (line   6)
+* C if-then-else output format:          If-then-else.        (line   6)
+* case difference suppression:           Case Folding.        (line   6)
+* ClearCase:                             Revision Control.    (line   6)
+* cmp invocation:                        Invoking cmp.        (line   6)
+* cmp options:                           cmp Options.         (line   6)
+* color, distinguishing different context: diff Options.      (line  37)
+* columnar output:                       Side by Side.        (line   6)
+* common mistakes with patches:          Avoiding Common Mistakes.
+                                                              (line   6)
+* comparing three files:                 Comparing Three Files.
+                                                              (line   6)
+* conflict:                              diff3 Merging.       (line  26)
+* conflict marking:                      Marking Conflicts.   (line   6)
+* context output format:                 Context.             (line   6)
+* creating files:                        Creating and Removing.
+                                                              (line   6)
+* de capability:                         diff Options.        (line 184)
+* diagnostics from patch:                patch Messages.      (line   6)
+* diff invocation:                       Invoking diff.       (line   6)
+* diff merging:                          Interactive Merging. (line   6)
+* diff options:                          diff Options.        (line   6)
+* diff sample input:                     Sample diff Input.   (line   6)
+* diff3 hunks:                           diff3 Hunks.         (line   6)
+* diff3 invocation:                      Invoking diff3.      (line   6)
+* diff3 options:                         diff3 Options.       (line   6)
+* diff3 sample input:                    Sample diff3 Input.  (line   6)
+* directories and patch:                 patch Directories.   (line   6)
+* directory structure changes:           Changing Structure.  (line   6)
+* dry runs for patch:                    Dry Runs.            (line   6)
+* ed script output format:               ed Scripts.          (line   6)
+* EDITOR:                                Merge Commands.      (line  50)
+* empty files, removing:                 Creating and Removing.
+                                                              (line   6)
+* exabyte, definition of:                cmp Options.         (line  99)
+* exbibyte, definition of:               cmp Options.         (line 102)
+* file name alternates:                  Alternate Names.     (line   6)
+* file names with unusual characters:    Unusual File Names.  (line   6)
+* format of diff output:                 Output Formats.      (line   6)
+* format of diff3 output:                Comparing Three Files.
+                                                              (line   6)
+* formats for if-then-else line groups:  Line Group Formats.  (line   6)
+* forward ed script output format:       Forward ed.          (line   6)
+* full lines:                            Incomplete Lines.    (line   6)
+* function headings, C:                  C Function Headings. (line   6)
+* fuzz factor when patching:             Inexact.             (line   6)
+* gibibyte, definition of:               cmp Options.         (line  87)
+* gigabyte, definition of:               cmp Options.         (line  84)
+* hd capability:                         diff Options.        (line 189)
+* headings:                              Sections.            (line   6)
+* hunks:                                 Hunks.               (line   6)
+* hunks for diff3:                       diff3 Hunks.         (line   6)
+* if-then-else output format:            If-then-else.        (line   6)
+* ifdef output format:                   If-then-else.        (line   6)
+* imperfect patch application:           Imperfect.           (line   6)
+* incomplete line merging:               Merging Incomplete Lines.
+                                                              (line   6)
+* incomplete lines:                      Incomplete Lines.    (line   6)
+* inexact patches:                       Inexact.             (line   6)
+* inhibit messages from patch:           More or Fewer Messages.
+                                                              (line   6)
+* interactive merging:                   Interactive Merging. (line   6)
+* introduction:                          Comparison.          (line   6)
+* intuiting file names from patches:     Multiple Patches.    (line   6)
+* invoking cmp:                          Invoking cmp.        (line   6)
+* invoking diff:                         Invoking diff.       (line   6)
+* invoking diff3:                        Invoking diff3.      (line   6)
+* invoking patch:                        Invoking patch.      (line   6)
+* invoking sdiff:                        Invoking sdiff.      (line   6)
+* keyboard input to patch:               patch and Keyboard Input.
+                                                              (line   6)
+* kibibyte, definition of:               cmp Options.         (line  75)
+* kilobyte, definition of:               cmp Options.         (line  71)
+* LC_COLLATE:                            Comparing Directories.
+                                                              (line   6)
+* LC_NUMERIC:                            Line Group Formats.  (line 143)
+* LC_TIME:                               Detailed Context.    (line  12)
+* line formats:                          Line Formats.        (line   6)
+* line group formats:                    Line Group Formats.  (line   6)
+* ln capability:                         diff Options.        (line 194)
+* mebibyte, definition of:               cmp Options.         (line  82)
+* megabyte, definition of:               cmp Options.         (line  79)
+* merge commands:                        Merge Commands.      (line   6)
+* merged diff3 format:                   Bypassing ed.        (line   6)
+* merged output format:                  If-then-else.        (line   6)
+* merging from a common ancestor:        diff3 Merging.       (line   6)
+* merging interactively:                 Merge Commands.      (line   6)
+* messages from patch:                   patch Messages.      (line   6)
+* multibyte characters:                  Internationalization.
+                                                              (line   6)
+* multiple patches:                      Multiple Patches.    (line   6)
+* newline treatment by diff:             Incomplete Lines.    (line   6)
+* none color option:                     diff Options.        (line  40)
+* normal output format:                  Normal.              (line   6)
+* options for cmp:                       cmp Options.         (line   6)
+* options for diff:                      diff Options.        (line   6)
+* options for diff3:                     diff3 Options.       (line   6)
+* options for patch:                     patch Options.       (line   6)
+* options for sdiff:                     sdiff Options.       (line   6)
+* output formats:                        Output Formats.      (line   6)
+* overlap:                               diff3 Merging.       (line  26)
+* overlapping change, selection of:      Which Changes.       (line   6)
+* overview of diff and patch:            Overview.            (line   6)
+* paginating diff output:                Pagination.          (line   6)
+* patch consumer tips:                   Tips for Patch Consumers.
+                                                              (line   6)
+* patch input format:                    patch Input.         (line   6)
+* patch invocation:                      Invoking patch.      (line   6)
+* patch messages and questions:          patch Messages.      (line   6)
+* patch options:                         patch Options.       (line   6)
+* patch producer tips:                   Tips for Patch Producers.
+                                                              (line   6)
+* patch, common mistakes:                Avoiding Common Mistakes.
+                                                              (line   6)
+* patches, shrinking:                    Generating Smaller Patches.
+                                                              (line   6)
+* patching directories:                  patch Directories.   (line   6)
+* PATCH_GET:                             Revision Control.    (line  13)
+* PATCH_VERSION_CONTROL:                 Backup Names.        (line  21)
+* pebibyte, definition of:               cmp Options.         (line  97)
+* performance of diff:                   diff Performance.    (line   6)
+* petabyte, definition of:               cmp Options.         (line  94)
+* POSIX:                                 patch and POSIX.     (line   6)
+* POSIX <1>:                             Standards conformance.
+                                                              (line   6)
+* POSIXLY_CORRECT:                       patch and POSIX.     (line   6)
+* POSIXLY_CORRECT <1>:                   Standards conformance.
+                                                              (line   6)
+* projects for directories:              Shortcomings.        (line   6)
+* quoting style:                         patch Quoting Style. (line   6)
+* QUOTING_STYLE:                         patch Quoting Style. (line  26)
+* RCS:                                   Revision Control.    (line   6)
+* RCS script output format:              RCS.                 (line   6)
+* regular expression matching headings:  Specified Headings.  (line   6)
+* regular expression suppression:        Specified Lines.     (line   6)
+* reject file names:                     Reject Names.        (line   6)
+* removing empty files:                  Creating and Removing.
+                                                              (line   6)
+* reporting bugs:                        Bugs.                (line   6)
+* reversed patches:                      Reversed Patches.    (line   6)
+* revision control:                      Revision Control.    (line   6)
+* sample input for diff:                 Sample diff Input.   (line   6)
+* sample input for diff3:                Sample diff3 Input.  (line   6)
+* SCCS:                                  Revision Control.    (line   6)
+* script output formats:                 Scripts.             (line   6)
+* sdiff invocation:                      Invoking sdiff.      (line   6)
+* sdiff options:                         sdiff Options.       (line   6)
+* sdiff output format:                   sdiff Option Summary.
+                                                              (line   6)
+* section headings:                      Sections.            (line   6)
+* side by side:                          Side by Side.        (line   6)
+* side by side format:                   Side by Side Format. (line   6)
+* SIMPLE_BACKUP_SUFFIX:                  Backup Names.        (line  12)
+* special files:                         Special Files.       (line   6)
+* specified headings:                    Specified Headings.  (line   6)
+* summarizing which files differ:        Brief.               (line   6)
+* System V diff3 compatibility:          Saving the Changed File.
+                                                              (line   6)
+* tab and blank difference suppression:  White Space.         (line   6)
+* tab stop alignment:                    Tabs.                (line   6)
+* tebibyte, definition of:               cmp Options.         (line  92)
+* terabyte, definition of:               cmp Options.         (line  89)
+* terminal, using color iff:             diff Options.        (line  42)
+* testing patch:                         Dry Runs.            (line   6)
+* text versus binary diff:               Binary.              (line   6)
+* time stamp format, context diffs:      Detailed Context.    (line  12)
+* time stamp format, unified diffs:      Detailed Unified.    (line  12)
+* time stamps on patched files:          Patching Time Stamps.
+                                                              (line   6)
+* traditional patch:                     patch and Tradition. (line   6)
+* trailing blanks:                       Trailing Blanks.     (line   6)
+* two-column output:                     Side by Side.        (line   6)
+* unified output format:                 Unified Format.      (line   6)
+* unmerged change:                       Which Changes.       (line   6)
+* varying-width characters:              Internationalization.
+                                                              (line   6)
+* verbose messages from patch:           More or Fewer Messages.
+                                                              (line   6)
+* version control:                       Revision Control.    (line   6)
+* VERSION_CONTROL:                       Revision Control.    (line  22)
+* VERSION_CONTROL <1>:                   Backup Names.        (line  21)
+* white space in patches:                Changed White Space. (line   6)
+* yottabyte, definition of:              cmp Options.         (line 110)
+* zettabyte, definition of:              cmp Options.         (line 104)
+
+
+
+Tag Table:
+Node: Top1432
+Node: Overview3646
+Node: Comparison7200
+Node: Hunks10144
+Node: White Space11587
+Node: Blank Lines13428
+Node: Specified Lines14419
+Node: Case Folding15547
+Node: Brief15966
+Node: Binary17291
+Node: Output Formats21090
+Node: Sample diff Input21817
+Node: Context23318
+Node: Context Format24897
+Node: Example Context25691
+Node: Less Context27201
+Node: Detailed Context28393
+Node: Unified Format30593
+Node: Example Unified31392
+Node: Detailed Unified32432
+Node: Sections34076
+Node: Specified Headings34837
+Node: C Function Headings36388
+Node: Alternate Names37236
+Node: Side by Side38151
+Node: Side by Side Format40303
+Node: Example Side by Side41207
+Node: Normal42549
+Node: Example Normal43552
+Node: Detailed Normal44291
+Node: Scripts46032
+Node: ed Scripts46439
+Node: Example ed47647
+Node: Detailed ed48099
+Node: Forward ed49860
+Node: RCS50638
+Node: If-then-else51856
+Node: Line Group Formats53536
+Node: Line Formats59419
+Node: Example If-then-else62690
+Node: Detailed If-then-else63771
+Node: Incomplete Lines65658
+Node: Comparing Directories67296
+Node: Adjusting Output71590
+Node: Tabs72099
+Node: Trailing Blanks73715
+Node: Pagination74942
+Node: diff Performance75412
+Node: Comparing Three Files78503
+Node: Sample diff3 Input79383
+Node: Example diff3 Normal80333
+Node: Detailed diff3 Normal81399
+Node: diff3 Hunks83189
+Node: diff3 Merging84457
+Node: Which Changes86704
+Node: Marking Conflicts88106
+Node: Bypassing ed90563
+Node: Merging Incomplete Lines91908
+Node: Saving the Changed File92636
+Node: Interactive Merging93254
+Node: sdiff Option Summary93965
+Node: Merge Commands95170
+Node: Merging with patch96461
+Node: patch Input98832
+Node: Revision Control99516
+Node: Imperfect100689
+Node: Changed White Space101840
+Node: Reversed Patches102639
+Node: Inexact104105
+Node: Dry Runs107663
+Node: Creating and Removing108529
+Node: Patching Time Stamps109581
+Node: Multiple Patches111782
+Node: patch Directories114446
+Node: Backups116072
+Node: Backup Names117139
+Ref: Backup Names-Footnote-1120096
+Node: Reject Names120223
+Node: patch Messages120814
+Node: More or Fewer Messages121876
+Node: patch and Keyboard Input122509
+Node: patch Quoting Style123540
+Node: patch and POSIX124688
+Node: patch and Tradition125529
+Node: Making Patches128953
+Node: Tips for Patch Producers129781
+Node: Tips for Patch Consumers131039
+Node: Avoiding Common Mistakes131678
+Node: Generating Smaller Patches134205
+Node: Invoking cmp135967
+Node: cmp Options137391
+Node: Invoking diff141037
+Node: diff Options142658
+Node: Invoking diff3152509
+Node: diff3 Options153149
+Node: Invoking patch156184
+Node: patch Options157394
+Node: Invoking sdiff162623
+Node: sdiff Options163767
+Node: Standards conformance166741
+Node: Projects168489
+Node: Shortcomings169203
+Node: Internationalization170307
+Node: Changing Structure171475
+Node: Special Files172581
+Node: Unusual File Names173694
+Node: Time Stamp Order174335
+Node: Ignoring Changes174980
+Node: Speedups175752
+Node: Bugs176218
+Node: Copying This Manual177073
+Node: Translations202194
+Node: Index202568
+
+End Tag Table