1 This is diff.info, produced by makeinfo version 4.2 from diff.texi.
3 This manual is for GNU Diffutils (version 2.8.1, 5 April 2002), and
4 documents the GNU `diff', `diff3', `sdiff', and `cmp' commands for
5 showing the differences between files and the GNU `patch' command for
6 using their output to update files.
8 Copyright (C) 1992, 1993, 1994, 1998, 2001, 2002 Free Software
11 Permission is granted to copy, distribute and/or modify this
12 document under the terms of the GNU Free Documentation License,
13 Version 1.1 or any later version published by the Free Software
14 Foundation; with no Invariant Sections, with the Front-Cover texts
15 being "A GNU Manual," and with the Back-Cover Texts as in (a)
16 below. A copy of the license is included in the section entitled
17 "GNU Free Documentation License."
19 (a) The FSF's Back-Cover Text is: "You have freedom to copy and
20 modify this GNU Manual, like GNU software. Copies published by
21 the Free Software Foundation raise funds for GNU development."
23 INFO-DIR-SECTION Individual utilities
25 * cmp: (diff)Invoking cmp. Compare 2 files byte by byte.
26 * diff: (diff)Invoking diff. Compare 2 files line by line.
27 * diff3: (diff)Invoking diff3. Compare 3 files line by line.
28 * patch: (diff)Invoking patch. Apply a patch to a file.
29 * sdiff: (diff)Invoking sdiff. Merge 2 files side-by-side.
32 INFO-DIR-SECTION GNU packages
34 * Diff: (diff). Comparing and merging files.
38 File: diff.info, Node: Top, Next: Overview, Up: (dir)
40 Comparing and Merging Files
41 ***************************
43 This manual is for GNU Diffutils (version 2.8.1, 5 April 2002), and
44 documents the GNU `diff', `diff3', `sdiff', and `cmp' commands for
45 showing the differences between files and the GNU `patch' command for
46 using their output to update files.
48 Copyright (C) 1992, 1993, 1994, 1998, 2001, 2002 Free Software
51 Permission is granted to copy, distribute and/or modify this
52 document under the terms of the GNU Free Documentation License,
53 Version 1.1 or any later version published by the Free Software
54 Foundation; with no Invariant Sections, with the Front-Cover texts
55 being "A GNU Manual," and with the Back-Cover Texts as in (a)
56 below. A copy of the license is included in the section entitled
57 "GNU Free Documentation License."
59 (a) The FSF's Back-Cover Text is: "You have freedom to copy and
60 modify this GNU Manual, like GNU software. Copies published by
61 the Free Software Foundation raise funds for GNU development."
65 * Overview:: Preliminary information.
66 * Comparison:: What file comparison means.
68 * Output Formats:: Formats for two-way difference reports.
69 * Incomplete Lines:: Lines that lack trailing newlines.
70 * Comparing Directories:: Comparing files and directories.
71 * Adjusting Output:: Making `diff' output prettier.
72 * diff Performance:: Making `diff' smarter or faster.
74 * Comparing Three Files:: Formats for three-way difference reports.
75 * diff3 Merging:: Merging from a common ancestor.
77 * Interactive Merging:: Interactive merging with `sdiff'.
79 * Merging with patch:: Using `patch' to change old files into new ones.
80 * Making Patches:: Tips for making and using patch distributions.
82 * Invoking cmp:: Compare two files byte by byte.
83 * Invoking diff:: Compare two files line by line.
84 * Invoking diff3:: Compare three files line by line.
85 * Invoking patch:: Apply a diff file to an original.
86 * Invoking sdiff:: Side-by-side merge of file differences.
88 * Standards conformance:: Conformance to the POSIX standard.
89 * Projects:: If you've found a bug or other shortcoming.
91 * Copying This Manual:: How to make copies of this manual.
95 File: diff.info, Node: Overview, Next: Comparison, Prev: Top, Up: Top
100 Computer users often find occasion to ask how two files differ.
101 Perhaps one file is a newer version of the other file. Or maybe the
102 two files started out as identical copies but were changed by different
105 You can use the `diff' command to show differences between two
106 files, or each corresponding file in two directories. `diff' outputs
107 differences between files line by line in any of several formats,
108 selectable by command line options. This set of differences is often
109 called a "diff" or "patch". For files that are identical, `diff'
110 normally produces no output; for binary (non-text) files, `diff'
111 normally reports only that they are different.
113 You can use the `cmp' command to show the byte and line numbers
114 where two files differ. `cmp' can also show all the bytes that differ
115 between the two files, side by side. A way to compare two files
116 character by character is the Emacs command `M-x compare-windows'.
117 *Note Other Window: (emacs)Other Window, for more information on that
120 You can use the `diff3' command to show differences among three
121 files. When two people have made independent changes to a common
122 original, `diff3' can report the differences between the original and
123 the two changed versions, and can produce a merged file that contains
124 both persons' changes together with warnings about conflicts.
126 You can use the `sdiff' command to merge two files interactively.
128 You can use the set of differences produced by `diff' to distribute
129 updates to text files (such as program source code) to other people.
130 This method is especially useful when the differences are small compared
131 to the complete files. Given `diff' output, you can use the `patch'
132 program to update, or "patch", a copy of the file. If you think of
133 `diff' as subtracting one file from another to produce their
134 difference, you can think of `patch' as adding the difference to one
135 file to reproduce the other.
137 This manual first concentrates on making diffs, and later shows how
138 to use diffs to update files.
140 GNU `diff' was written by Paul Eggert, Mike Haertel, David Hayes,
141 Richard Stallman, and Len Tower. Wayne Davison designed and
142 implemented the unified output format. The basic algorithm is described
143 in "An O(ND) Difference Algorithm and its Variations", Eugene W. Myers,
144 `Algorithmica' Vol. 1 No. 2, 1986, pp. 251-266; and in "A File
145 Comparison Program", Webb Miller and Eugene W. Myers,
146 `Software--Practice and Experience' Vol. 15 No. 11, 1985, pp. 1025-1040.
147 The algorithm was independently discovered as described in "Algorithms
148 for Approximate String Matching", E. Ukkonen, `Information and Control'
149 Vol. 64, 1985, pp. 100-118.
151 GNU `diff3' was written by Randy Smith. GNU `sdiff' was written by
152 Thomas Lord. GNU `cmp' was written by Torbjorn Granlund and David
155 `patch' was written mainly by Larry Wall and Paul Eggert; several
156 GNU enhancements were contributed by Wayne Davison and David MacKenzie.
157 Parts of this manual are adapted from a manual page written by Larry
158 Wall, with his permission.
161 File: diff.info, Node: Comparison, Next: Output Formats, Prev: Overview, Up: Top
163 What Comparison Means
164 *********************
166 There are several ways to think about the differences between two
167 files. One way to think of the differences is as a series of lines
168 that were deleted from, inserted in, or changed in one file to produce
169 the other file. `diff' compares two files line by line, finds groups of
170 lines that differ, and reports each group of differing lines. It can
171 report the differing lines in several formats, which have different
174 GNU `diff' can show whether files are different without detailing
175 the differences. It also provides ways to suppress certain kinds of
176 differences that are not important to you. Most commonly, such
177 differences are changes in the amount of white space between words or
178 lines. `diff' also provides ways to suppress differences in alphabetic
179 case or in lines that match a regular expression that you provide.
180 These options can accumulate; for example, you can ignore changes in
181 both white space and alphabetic case.
183 Another way to think of the differences between two files is as a
184 sequence of pairs of bytes that can be either identical or different.
185 `cmp' reports the differences between two files byte by byte, instead
186 of line by line. As a result, it is often more useful than `diff' for
187 comparing binary files. For text files, `cmp' is useful mainly when
188 you want to know only whether two files are identical, or whether one
189 file is a prefix of the other.
191 To illustrate the effect that considering changes byte by byte can
192 have compared with considering them line by line, think of what happens
193 if a single newline character is added to the beginning of a file. If
194 that file is then compared with an otherwise identical file that lacks
195 the newline at the beginning, `diff' will report that a blank line has
196 been added to the file, while `cmp' will report that almost every byte
197 of the two files differs.
199 `diff3' normally compares three input files line by line, finds
200 groups of lines that differ, and reports each group of differing lines.
201 Its output is designed to make it easy to inspect two different sets of
202 changes to the same file.
206 * Hunks:: Groups of differing lines.
207 * White Space:: Suppressing differences in white space.
208 * Blank Lines:: Suppressing differences in blank lines.
209 * Case Folding:: Suppressing differences in alphabetic case.
210 * Specified Folding:: Suppressing differences that match regular expressions.
211 * Brief:: Summarizing which files are different.
212 * Binary:: Comparing binary files or forcing text comparisons.
215 File: diff.info, Node: Hunks, Next: White Space, Up: Comparison
220 When comparing two files, `diff' finds sequences of lines common to
221 both files, interspersed with groups of differing lines called "hunks".
222 Comparing two identical files yields one sequence of common lines and
223 no hunks, because no lines differ. Comparing two entirely different
224 files yields no common lines and one large hunk that contains all lines
225 of both files. In general, there are many ways to match up lines
226 between two given files. `diff' tries to minimize the total hunk size
227 by finding large sequences of common lines interspersed with small
228 hunks of differing lines.
230 For example, suppose the file `F' contains the three lines `a', `b',
231 `c', and the file `G' contains the same three lines in reverse order
232 `c', `b', `a'. If `diff' finds the line `c' as common, then the command
233 `diff F G' produces this output:
242 But if `diff' notices the common line `b' instead, it produces this
254 It is also possible to find `a' as the common line. `diff' does not
255 always find an optimal matching between the files; it takes shortcuts
256 to run faster. But its output is usually close to the shortest
257 possible. You can adjust this tradeoff with the `--minimal' option
258 (*note diff Performance::).
261 File: diff.info, Node: White Space, Next: Blank Lines, Prev: Hunks, Up: Comparison
263 Suppressing Differences in Blank and Tab Spacing
264 ================================================
266 The `-E' and `--ignore-tab-expansion' options ignore the distinction
267 between tabs and spaces on input. A tab is considered to be equivalent
268 to the number of spaces to the next tab stop. `diff' assumes that tab
269 stops are set every 8 print columns.
271 The `-b' and `--ignore-space-change' options are stronger. They
272 ignore white space at line end, and consider all other sequences of one
273 or more white space characters to be equivalent. With these options,
274 `diff' considers the following two lines to be equivalent, where `$'
275 denotes the line end:
277 Here lyeth muche rychnesse in lytell space. -- John Heywood$
278 Here lyeth muche rychnesse in lytell space. -- John Heywood $
280 The `-w' and `--ignore-all-space' options are stronger still. They
281 ignore difference even if one line has white space where the other line
282 has none. "White space" characters include tab, newline, vertical tab,
283 form feed, carriage return, and space; some locales may define
284 additional characters to be white space. With these options, `diff'
285 considers the following two lines to be equivalent, where `$' denotes
286 the line end and `^M' denotes a carriage return:
288 Here lyeth muche rychnesse in lytell space.-- John Heywood$
289 He relyeth much erychnes seinly tells pace. --John Heywood ^M$
292 File: diff.info, Node: Blank Lines, Next: Case Folding, Prev: White Space, Up: Comparison
294 Suppressing Differences in Blank Lines
295 ======================================
297 The `-B' and `--ignore-blank-lines' options ignore insertions or
298 deletions of blank lines. These options affect only lines that are
299 completely empty; they do not affect lines that look empty but contain
300 space or tab characters. With these options, for example, a file
302 1. A point is that which has no part.
304 2. A line is breadthless length.
305 -- Euclid, The Elements, I
307 is considered identical to a file containing
308 1. A point is that which has no part.
309 2. A line is breadthless length.
312 -- Euclid, The Elements, I
315 File: diff.info, Node: Case Folding, Next: Specified Folding, Prev: Blank Lines, Up: Comparison
317 Suppressing Case Differences
318 ============================
320 GNU `diff' can treat lower case letters as equivalent to their upper
321 case counterparts, so that, for example, it considers `Funky Stuff',
322 `funky STUFF', and `fUNKy stuFf' to all be the same. To request this,
323 use the `-i' or `--ignore-case' option.
326 File: diff.info, Node: Specified Folding, Next: Brief, Prev: Case Folding, Up: Comparison
328 Suppressing Lines Matching a Regular Expression
329 ===============================================
331 To ignore insertions and deletions of lines that match a
332 `grep'-style regular expression, use the `-I REGEXP' or
333 `--ignore-matching-lines=REGEXP' option. You should escape regular
334 expressions that contain shell metacharacters to prevent the shell from
335 expanding them. For example, `diff -I '^[[:digit:]]'' ignores all
336 changes to lines beginning with a digit.
338 However, `-I' only ignores the insertion or deletion of lines that
339 contain the regular expression if every changed line in the hunk--every
340 insertion and every deletion--matches the regular expression. In other
341 words, for each nonignorable change, `diff' prints the complete set of
342 changes in its vicinity, including the ignorable ones.
344 You can specify more than one regular expression for lines to ignore
345 by using more than one `-I' option. `diff' tries to match each line
346 against each regular expression.
349 File: diff.info, Node: Brief, Next: Binary, Prev: Specified Folding, Up: Comparison
351 Summarizing Which Files Differ
352 ==============================
354 When you only want to find out whether files are different, and you
355 don't care what the differences are, you can use the summary output
356 format. In this format, instead of showing the differences between the
357 files, `diff' simply reports whether files differ. The `-q' and
358 `--brief' options select this output format.
360 This format is especially useful when comparing the contents of two
361 directories. It is also much faster than doing the normal line by line
362 comparisons, because `diff' can stop analyzing the files as soon as it
363 knows that there are any differences.
365 You can also get a brief indication of whether two files differ by
366 using `cmp'. For files that are identical, `cmp' produces no output.
367 When the files differ, by default, `cmp' outputs the byte and line
368 number where the first difference occurs. You can use the `-s' option
369 to suppress that information, so that `cmp' produces no output and
370 reports whether the files differ using only its exit status (*note
373 Unlike `diff', `cmp' cannot compare directories; it can only compare
377 File: diff.info, Node: Binary, Prev: Brief, Up: Comparison
379 Binary Files and Forcing Text Comparisons
380 =========================================
382 If `diff' thinks that either of the two files it is comparing is
383 binary (a non-text file), it normally treats that pair of files much as
384 if the summary output format had been selected (*note Brief::), and
385 reports only that the binary files are different. This is because line
386 by line comparisons are usually not meaningful for binary files.
388 `diff' determines whether a file is text or binary by checking the
389 first few bytes in the file; the exact number of bytes is system
390 dependent, but it is typically several thousand. If every byte in that
391 part of the file is non-null, `diff' considers the file to be text;
392 otherwise it considers the file to be binary.
394 Sometimes you might want to force `diff' to consider files to be
395 text. For example, you might be comparing text files that contain null
396 characters; `diff' would erroneously decide that those are non-text
397 files. Or you might be comparing documents that are in a format used
398 by a word processing system that uses null characters to indicate
399 special formatting. You can force `diff' to consider all files to be
400 text files, and compare them line by line, by using the `-a' or
401 `--text' option. If the files you compare using this option do not in
402 fact contain text, they will probably contain few newline characters,
403 and the `diff' output will consist of hunks showing differences between
404 long lines of whatever characters the files contain.
406 You can also force `diff' to consider all files to be binary files,
407 and report only whether they differ (but not how). Use the `-q' or
408 `--brief' option for this.
410 Differing binary files are considered to cause trouble because the
411 resulting `diff' output does not capture all the differences. This
412 trouble causes `diff' to exit with status 2. However, this trouble
413 cannot occur with the `--a' or `--text' option, or with the `-q' or
414 `--brief' option, as these options both cause `diff' to treat binary
415 files like text files.
417 In operating systems that distinguish between text and binary files,
418 `diff' normally reads and writes all data as text. Use the `--binary'
419 option to force `diff' to read and write binary data instead. This
420 option has no effect on a POSIX-compliant system like GNU or
421 traditional Unix. However, many personal computer operating systems
422 represent the end of a line with a carriage return followed by a
423 newline. On such systems, `diff' normally ignores these carriage
424 returns on input and generates them at the end of each output line, but
425 with the `--binary' option `diff' treats each carriage return as just
426 another input character, and does not generate a carriage return at the
427 end of each output line. This can be useful when dealing with non-text
428 files that are meant to be interchanged with POSIX-compliant systems.
430 The `--strip-trailing-cr' causes `diff' to treat input lines that
431 end in carriage return followed by newline as if they end in plain
432 newline. This can be useful when comparing text that is imperfectly
433 imported from many personal computer operating systems. This option
434 affects how lines are read, which in turn affects how they are compared
437 If you want to compare two files byte by byte, you can use the `cmp'
438 program with the `-l' option to show the values of each differing byte
439 in the two files. With GNU `cmp', you can also use the `-b' option to
440 show the ASCII representation of those bytes. *Note Invoking cmp::,
441 for more information.
443 If `diff3' thinks that any of the files it is comparing is binary (a
444 non-text file), it normally reports an error, because such comparisons
445 are usually not useful. `diff3' uses the same test as `diff' to decide
446 whether a file is binary. As with `diff', if the input files contain a
447 few non-text bytes but otherwise are like text files, you can force
448 `diff3' to consider all files to be text files and compare them line by
449 line by using the `-a' or `--text' options.
452 File: diff.info, Node: Output Formats, Next: Incomplete Lines, Prev: Comparison, Up: Top
454 `diff' Output Formats
455 *********************
457 `diff' has several mutually exclusive options for output format.
458 The following sections describe each format, illustrating how `diff'
459 reports the differences between two sample input files.
463 * Sample diff Input:: Sample `diff' input files for examples.
464 * Normal:: Showing differences without surrounding text.
465 * Context:: Showing differences with the surrounding text.
466 * Side by Side:: Showing differences in two columns.
467 * Scripts:: Generating scripts for other programs.
468 * If-then-else:: Merging files with if-then-else.
471 File: diff.info, Node: Sample diff Input, Next: Normal, Up: Output Formats
473 Two Sample Input Files
474 ======================
476 Here are two sample files that we will use in numerous examples to
477 illustrate the output of `diff' and how various options can change it.
479 This is the file `lao':
481 The Way that can be told of is not the eternal Way;
482 The name that can be named is not the eternal name.
483 The Nameless is the origin of Heaven and Earth;
484 The Named is the mother of all things.
485 Therefore let there always be non-being,
486 so we may see their subtlety,
487 And let there always be being,
488 so we may see their outcome.
489 The two are the same,
490 But after they are produced,
491 they have different names.
493 This is the file `tzu':
495 The Nameless is the origin of Heaven and Earth;
496 The named is the mother of all things.
498 Therefore let there always be non-being,
499 so we may see their subtlety,
500 And let there always be being,
501 so we may see their outcome.
502 The two are the same,
503 But after they are produced,
504 they have different names.
505 They both may be called deep and profound.
506 Deeper and more profound,
507 The door of all subtleties!
509 In this example, the first hunk contains just the first two lines of
510 `lao', the second hunk contains the fourth line of `lao' opposing the
511 second and third lines of `tzu', and the last hunk contains just the
512 last three lines of `tzu'.
515 File: diff.info, Node: Normal, Next: Context, Prev: Sample diff Input, Up: Output Formats
517 Showing Differences Without Context
518 ===================================
520 The "normal" `diff' output format shows each hunk of differences
521 without any surrounding context. Sometimes such output is the clearest
522 way to see how lines have changed, without the clutter of nearby
523 unchanged lines (although you can get similar results with the context
524 or unified formats by using 0 lines of context). However, this format
525 is no longer widely used for sending out patches; for that purpose, the
526 context format (*note Context Format::) and the unified format (*note
527 Unified Format::) are superior. Normal format is the default for
528 compatibility with older versions of `diff' and the POSIX standard.
529 Use the `--normal' option to select this output format explicitly.
533 * Detailed Normal:: A detailed description of normal output format.
534 * Example Normal:: Sample output in the normal format.
537 File: diff.info, Node: Detailed Normal, Next: Example Normal, Up: Normal
539 Detailed Description of Normal Format
540 -------------------------------------
542 The normal output format consists of one or more hunks of
543 differences; each hunk shows one area where the files differ. Normal
544 format hunks look like this:
553 There are three types of change commands. Each consists of a line
554 number or comma-separated range of lines in the first file, a single
555 character indicating the kind of change to make, and a line number or
556 comma-separated range of lines in the second file. All line numbers are
557 the original line numbers in each file. The types of change commands
561 Add the lines in range R of the second file after line L of the
562 first file. For example, `8a12,15' means append lines 12-15 of
563 file 2 after line 8 of file 1; or, if changing file 2 into file 1,
564 delete lines 12-15 of file 2.
567 Replace the lines in range F of the first file with lines in range
568 T of the second file. This is like a combined add and delete, but
569 more compact. For example, `5,7c8,10' means change lines 5-7 of
570 file 1 to read as lines 8-10 of file 2; or, if changing file 2 into
571 file 1, change lines 8-10 of file 2 to read as lines 5-7 of file 1.
574 Delete the lines in range R from the first file; line L is where
575 they would have appeared in the second file had they not been
576 deleted. For example, `5,7d3' means delete lines 5-7 of file 1;
577 or, if changing file 2 into file 1, append lines 5-7 of file 1
578 after line 3 of file 2.
581 File: diff.info, Node: Example Normal, Prev: Detailed Normal, Up: Normal
583 An Example of Normal Format
584 ---------------------------
586 Here is the output of the command `diff lao tzu' (*note Sample diff
587 Input::, for the complete contents of the two files). Notice that it
588 shows only the lines that are different between the two files.
591 < The Way that can be told of is not the eternal Way;
592 < The name that can be named is not the eternal name.
594 < The Named is the mother of all things.
596 > The named is the mother of all things.
599 > They both may be called deep and profound.
600 > Deeper and more profound,
601 > The door of all subtleties!
604 File: diff.info, Node: Context, Next: Side by Side, Prev: Normal, Up: Output Formats
606 Showing Differences in Their Context
607 ====================================
609 Usually, when you are looking at the differences between files, you
610 will also want to see the parts of the files near the lines that
611 differ, to help you understand exactly what has changed. These nearby
612 parts of the files are called the "context".
614 GNU `diff' provides two output formats that show context around the
615 differing lines: "context format" and "unified format". It can
616 optionally show in which function or section of the file the differing
619 If you are distributing new versions of files to other people in the
620 form of `diff' output, you should use one of the output formats that
621 show context so that they can apply the diffs even if they have made
622 small changes of their own to the files. `patch' can apply the diffs
623 in this case by searching in the files for the lines of context around
624 the differing lines; if those lines are actually a few lines away from
625 where the diff says they are, `patch' can adjust the line numbers
626 accordingly and still apply the diff correctly. *Note Imperfect::, for
627 more information on using `patch' to apply imperfect diffs.
631 * Context Format:: An output format that shows surrounding lines.
632 * Unified Format:: A more compact output format that shows context.
633 * Sections:: Showing which sections of the files differences are in.
634 * Alternate Names:: Showing alternate file names in context headers.
637 File: diff.info, Node: Context Format, Next: Unified Format, Up: Context
642 The context output format shows several lines of context around the
643 lines that differ. It is the standard format for distributing updates
646 To select this output format, use the `-C LINES',
647 `--context[=LINES]', or `-c' option. The argument LINES that some of
648 these options take is the number of lines of context to show. If you
649 do not specify LINES, it defaults to three. For proper operation,
650 `patch' typically needs at least two lines of context.
654 * Detailed Context:: A detailed description of the context output format.
655 * Example Context:: Sample output in context format.
656 * Less Context:: Another sample with less context.
659 File: diff.info, Node: Detailed Context, Next: Example Context, Up: Context Format
661 Detailed Description of Context Format
662 ......................................
664 The context output format starts with a two-line header, which looks
667 *** FROM-FILE FROM-FILE-MODIFICATION-TIME
668 --- TO-FILE TO-FILE-MODIFICATION TIME
670 The time stamp normally looks like `2002-02-21 23:30:39.942229878
671 -0800' to indicate the date, time with fractional seconds, and time
672 zone in Internet RFC 2822 format
673 (ftp://ftp.isi.edu/in-notes/rfc2822.txt). However, a traditional time
674 stamp like `Thu Feb 21 23:30:39 2002' is used if the `LC_TIME' locale
675 category is either `C' or `POSIX'.
677 You can change the header's content with the `--label=LABEL' option;
678 see *Note Alternate Names::.
680 Next come one or more hunks of differences; each hunk shows one area
681 where the files differ. Context format hunks look like this:
684 *** FROM-FILE-LINE-RANGE ****
687 --- TO-FILE-LINE-RANGE ----
691 The lines of context around the lines that differ start with two
692 space characters. The lines that differ between the two files start
693 with one of the following indicator characters, followed by a space
697 A line that is part of a group of one or more lines that changed
698 between the two files. There is a corresponding group of lines
699 marked with `!' in the part of this hunk for the other file.
702 An "inserted" line in the second file that corresponds to nothing
706 A "deleted" line in the first file that corresponds to nothing in
709 If all of the changes in a hunk are insertions, the lines of
710 FROM-FILE are omitted. If all of the changes are deletions, the lines
711 of TO-FILE are omitted.
714 File: diff.info, Node: Example Context, Next: Less Context, Prev: Detailed Context, Up: Context Format
716 An Example of Context Format
717 ............................
719 Here is the output of `diff -c lao tzu' (*note Sample diff Input::,
720 for the complete contents of the two files). Notice that up to three
721 lines that are not different are shown around each line that is
722 different; they are the context lines. Also notice that the first two
723 hunks have run together, because their contents overlap.
725 *** lao 2002-02-21 23:30:39.942229878 -0800
726 --- tzu 2002-02-21 23:30:50.442260588 -0800
729 - The Way that can be told of is not the eternal Way;
730 - The name that can be named is not the eternal name.
731 The Nameless is the origin of Heaven and Earth;
732 ! The Named is the mother of all things.
733 Therefore let there always be non-being,
734 so we may see their subtlety,
735 And let there always be being,
737 The Nameless is the origin of Heaven and Earth;
738 ! The named is the mother of all things.
740 Therefore let there always be non-being,
741 so we may see their subtlety,
742 And let there always be being,
746 The two are the same,
747 But after they are produced,
748 they have different names.
749 + They both may be called deep and profound.
750 + Deeper and more profound,
751 + The door of all subtleties!
754 File: diff.info, Node: Less Context, Prev: Example Context, Up: Context Format
756 An Example of Context Format with Less Context
757 ..............................................
759 Here is the output of `diff -C 1 lao tzu' (*note Sample diff
760 Input::, for the complete contents of the two files). Notice that at
761 most one context line is reported here.
763 *** lao 2002-02-21 23:30:39.942229878 -0800
764 --- tzu 2002-02-21 23:30:50.442260588 -0800
767 - The Way that can be told of is not the eternal Way;
768 - The name that can be named is not the eternal name.
769 The Nameless is the origin of Heaven and Earth;
770 ! The Named is the mother of all things.
771 Therefore let there always be non-being,
773 The Nameless is the origin of Heaven and Earth;
774 ! The named is the mother of all things.
776 Therefore let there always be non-being,
780 they have different names.
781 + They both may be called deep and profound.
782 + Deeper and more profound,
783 + The door of all subtleties!
786 File: diff.info, Node: Unified Format, Next: Sections, Prev: Context Format, Up: Context
791 The unified output format is a variation on the context format that
792 is more compact because it omits redundant context lines. To select
793 this output format, use the `-U LINES', `--unified[=LINES]', or `-u'
794 option. The argument LINES is the number of lines of context to show.
795 When it is not given, it defaults to three.
797 At present, only GNU `diff' can produce this format and only GNU
798 `patch' can automatically apply diffs in this format. For proper
799 operation, `patch' typically needs at least three lines of context.
803 * Detailed Unified:: A detailed description of unified format.
804 * Example Unified:: Sample output in unified format.
807 File: diff.info, Node: Detailed Unified, Next: Example Unified, Up: Unified Format
809 Detailed Description of Unified Format
810 ......................................
812 The unified output format starts with a two-line header, which looks
815 --- FROM-FILE FROM-FILE-MODIFICATION-TIME
816 +++ TO-FILE TO-FILE-MODIFICATION-TIME
818 The time stamp looks like `2002-02-21 23:30:39.942229878 -0800' to
819 indicate the date, time with fractional seconds, and time zone.
821 You can change the header's content with the `--label=LABEL' option;
822 see *Note Alternate Names::.
824 Next come one or more hunks of differences; each hunk shows one area
825 where the files differ. Unified format hunks look like this:
827 @@ FROM-FILE-RANGE TO-FILE-RANGE @@
828 LINE-FROM-EITHER-FILE
829 LINE-FROM-EITHER-FILE...
831 The lines common to both files begin with a space character. The
832 lines that actually differ between the two files have one of the
833 following indicator characters in the left print column:
836 A line was added here to the first file.
839 A line was removed here from the first file.
842 File: diff.info, Node: Example Unified, Prev: Detailed Unified, Up: Unified Format
844 An Example of Unified Format
845 ............................
847 Here is the output of the command `diff -u lao tzu' (*note Sample
848 diff Input::, for the complete contents of the two files):
850 --- lao 2002-02-21 23:30:39.942229878 -0800
851 +++ tzu 2002-02-21 23:30:50.442260588 -0800
853 -The Way that can be told of is not the eternal Way;
854 -The name that can be named is not the eternal name.
855 The Nameless is the origin of Heaven and Earth;
856 -The Named is the mother of all things.
857 +The named is the mother of all things.
859 Therefore let there always be non-being,
860 so we may see their subtlety,
861 And let there always be being,
863 The two are the same,
864 But after they are produced,
865 they have different names.
866 +They both may be called deep and profound.
867 +Deeper and more profound,
868 +The door of all subtleties!
871 File: diff.info, Node: Sections, Next: Alternate Names, Prev: Unified Format, Up: Context
873 Showing Which Sections Differences Are in
874 -----------------------------------------
876 Sometimes you might want to know which part of the files each change
877 falls in. If the files are source code, this could mean which function
878 was changed. If the files are documents, it could mean which chapter or
879 appendix was changed. GNU `diff' can show this by displaying the
880 nearest section heading line that precedes the differing lines. Which
881 lines are "section headings" is determined by a regular expression.
885 * Specified Headings:: Showing headings that match regular expressions.
886 * C Function Headings:: Showing headings of C functions.
889 File: diff.info, Node: Specified Headings, Next: C Function Headings, Up: Sections
891 Showing Lines That Match Regular Expressions
892 ............................................
894 To show in which sections differences occur for files that are not
895 source code for C or similar languages, use the `-F REGEXP' or
896 `--show-function-line=REGEXP' option. `diff' considers lines that
897 match the `grep'-style regular expression REGEXP to be the beginning of
898 a section of the file. Here are suggested regular expressions for some
910 This option does not automatically select an output format; in order
911 to use it, you must select the context format (*note Context Format::)
912 or unified format (*note Unified Format::). In other output formats it
915 The `-F' and `--show-function-line' options find the nearest
916 unchanged line that precedes each hunk of differences and matches the
917 given regular expression. Then they add that line to the end of the
918 line of asterisks in the context format, or to the `@@' line in unified
919 format. If no matching line exists, they leave the output for that
920 hunk unchanged. If that line is more than 40 characters long, they
921 output only the first 40 characters. You can specify more than one
922 regular expression for such lines; `diff' tries to match each line
923 against each regular expression, starting with the last one given. This
924 means that you can use `-p' and `-F' together, if you wish.
927 File: diff.info, Node: C Function Headings, Prev: Specified Headings, Up: Sections
929 Showing C Function Headings
930 ...........................
932 To show in which functions differences occur for C and similar
933 languages, you can use the `-p' or `--show-c-function' option. This
934 option automatically defaults to the context output format (*note
935 Context Format::), with the default number of lines of context. You
936 can override that number with `-C LINES' elsewhere in the command line.
937 You can override both the format and the number with `-U LINES'
938 elsewhere in the command line.
940 The `-p' and `--show-c-function' options are equivalent to `-F
941 '^[[:alpha:]$_]'' if the unified format is specified, otherwise `-c -F
942 '^[[:alpha:]$_]'' (*note Specified Headings::). GNU `diff' provides
943 them for the sake of convenience.
946 File: diff.info, Node: Alternate Names, Prev: Sections, Up: Context
948 Showing Alternate File Names
949 ----------------------------
951 If you are comparing two files that have meaningless or uninformative
952 names, you might want `diff' to show alternate names in the header of
953 the context and unified output formats. To do this, use the
954 `--label=LABEL' option. The first time you give this option, its
955 argument replaces the name and date of the first file in the header;
956 the second time, its argument replaces the name and date of the second
957 file. If you give this option more than twice, `diff' reports an
958 error. The `--label' option does not affect the file names in the `pr'
959 header when the `-l' or `--paginate' option is used (*note
962 Here are the first two lines of the output from `diff -C 2
963 --label=original --label=modified lao tzu':
969 File: diff.info, Node: Side by Side, Next: Scripts, Prev: Context, Up: Output Formats
971 Showing Differences Side by Side
972 ================================
974 `diff' can produce a side by side difference listing of two files.
975 The files are listed in two columns with a gutter between them. The
976 gutter contains one of the following markers:
979 The corresponding lines are in common. That is, either the lines
980 are identical, or the difference is ignored because of one of the
981 `--ignore' options (*note White Space::).
984 The corresponding lines differ, and they are either both complete
988 The files differ and only the first file contains the line.
991 The files differ and only the second file contains the line.
994 Only the first file contains the line, but the difference is
998 Only the second file contains the line, but the difference is
1002 The corresponding lines differ, and only the first line is
1006 The corresponding lines differ, and only the second line is
1009 Normally, an output line is incomplete if and only if the lines that
1010 it contains are incomplete; *Note Incomplete Lines::. However, when an
1011 output line represents two differing lines, one might be incomplete
1012 while the other is not. In this case, the output line is complete, but
1013 its the gutter is marked `\' if the first line is incomplete, `/' if
1016 Side by side format is sometimes easiest to read, but it has
1017 limitations. It generates much wider output than usual, and truncates
1018 lines that are too long to fit. Also, it relies on lining up output
1019 more heavily than usual, so its output looks particularly bad if you
1020 use varying width fonts, nonstandard tab stops, or nonprinting
1023 You can use the `sdiff' command to interactively merge side by side
1024 differences. *Note Interactive Merging::, for more information on
1029 * Side by Side Format:: Controlling side by side output format.
1030 * Example Side by Side:: Sample side by side output.
1033 File: diff.info, Node: Side by Side Format, Next: Example Side by Side, Up: Side by Side
1035 Controlling Side by Side Format
1036 -------------------------------
1038 The `-y' or `--side-by-side' option selects side by side format.
1039 Because side by side output lines contain two input lines, the output
1040 is wider than usual: normally 130 print columns, which can fit onto a
1041 traditional printer line. You can set the width of the output with the
1042 `-W COLUMNS' or `--width=COLUMNS' option. The output is split into two
1043 halves of equal width, separated by a small gutter to mark differences;
1044 the right half is aligned to a tab stop so that tabs line up. Input
1045 lines that are too long to fit in half of an output line are truncated
1048 The `--left-column' option prints only the left column of two common
1049 lines. The `--suppress-common-lines' option suppresses common lines
1053 File: diff.info, Node: Example Side by Side, Prev: Side by Side Format, Up: Side by Side
1055 An Example of Side by Side Format
1056 ---------------------------------
1058 Here is the output of the command `diff -y -W 72 lao tzu' (*note
1059 Sample diff Input::, for the complete contents of the two files).
1061 The Way that can be told of is n <
1062 The name that can be named is no <
1063 The Nameless is the origin of He The Nameless is the origin of He
1064 The Named is the mother of all t | The named is the mother of all t
1066 Therefore let there always be no Therefore let there always be no
1067 so we may see their subtlety, so we may see their subtlety,
1068 And let there always be being, And let there always be being,
1069 so we may see their outcome. so we may see their outcome.
1070 The two are the same, The two are the same,
1071 But after they are produced, But after they are produced,
1072 they have different names. they have different names.
1073 > They both may be called deep and
1074 > Deeper and more profound,
1075 > The door of all subtleties!
1078 File: diff.info, Node: Scripts, Next: If-then-else, Prev: Side by Side, Up: Output Formats
1083 Several output modes produce command scripts for editing FROM-FILE
1088 * ed Scripts:: Using `diff' to produce commands for `ed'.
1089 * Forward ed:: Making forward `ed' scripts.
1090 * RCS:: A special `diff' output format used by RCS.
1093 File: diff.info, Node: ed Scripts, Next: Forward ed, Up: Scripts
1098 `diff' can produce commands that direct the `ed' text editor to
1099 change the first file into the second file. Long ago, this was the
1100 only output mode that was suitable for editing one file into another
1101 automatically; today, with `patch', it is almost obsolete. Use the
1102 `-e' or `--ed' option to select this output format.
1104 Like the normal format (*note Normal::), this output format does not
1105 show any context; unlike the normal format, it does not include the
1106 information necessary to apply the diff in reverse (to produce the first
1107 file if all you have is the second file and the diff).
1109 If the file `d' contains the output of `diff -e old new', then the
1110 command `(cat d && echo w) | ed - old' edits `old' to make it a copy of
1111 `new'. More generally, if `d1', `d2', ..., `dN' contain the outputs of
1112 `diff -e old new1', `diff -e new1 new2', ..., `diff -e newN-1 newN',
1113 respectively, then the command `(cat d1 d2 ... dN && echo w) | ed -
1114 old' edits `old' to make it a copy of `newN'.
1118 * Detailed ed:: A detailed description of `ed' format.
1119 * Example ed:: A sample `ed' script.
1122 File: diff.info, Node: Detailed ed, Next: Example ed, Up: ed Scripts
1124 Detailed Description of `ed' Format
1125 ...................................
1127 The `ed' output format consists of one or more hunks of differences.
1128 The changes closest to the ends of the files come first so that
1129 commands that change the number of lines do not affect how `ed'
1130 interprets line numbers in succeeding commands. `ed' format hunks look
1138 Because `ed' uses a single period on a line to indicate the end of
1139 input, GNU `diff' protects lines of changes that contain a single
1140 period on a line by writing two periods instead, then writing a
1141 subsequent `ed' command to change the two periods into one. The `ed'
1142 format cannot represent an incomplete line, so if the second file ends
1143 in a changed incomplete line, `diff' reports an error and then pretends
1144 that a newline was appended.
1146 There are three types of change commands. Each consists of a line
1147 number or comma-separated range of lines in the first file and a single
1148 character indicating the kind of change to make. All line numbers are
1149 the original line numbers in the file. The types of change commands
1153 Add text from the second file after line L in the first file. For
1154 example, `8a' means to add the following lines after line 8 of file
1158 Replace the lines in range R in the first file with the following
1159 lines. Like a combined add and delete, but more compact. For
1160 example, `5,7c' means change lines 5-7 of file 1 to read as the
1164 Delete the lines in range R from the first file. For example,
1165 `5,7d' means delete lines 5-7 of file 1.
1168 File: diff.info, Node: Example ed, Prev: Detailed ed, Up: ed Scripts
1173 Here is the output of `diff -e lao tzu' (*note Sample diff Input::,
1174 for the complete contents of the two files):
1177 They both may be called deep and profound.
1178 Deeper and more profound,
1179 The door of all subtleties!
1182 The named is the mother of all things.
1188 File: diff.info, Node: Forward ed, Next: RCS, Prev: ed Scripts, Up: Scripts
1190 Forward `ed' Scripts
1191 --------------------
1193 `diff' can produce output that is like an `ed' script, but with
1194 hunks in forward (front to back) order. The format of the commands is
1195 also changed slightly: command characters precede the lines they
1196 modify, spaces separate line numbers in ranges, and no attempt is made
1197 to disambiguate hunk lines consisting of a single period. Like `ed'
1198 format, forward `ed' format cannot represent incomplete lines.
1200 Forward `ed' format is not very useful, because neither `ed' nor
1201 `patch' can apply diffs in this format. It exists mainly for
1202 compatibility with older versions of `diff'. Use the `-f' or
1203 `--forward-ed' option to select it.
1206 File: diff.info, Node: RCS, Prev: Forward ed, Up: Scripts
1211 The RCS output format is designed specifically for use by the
1212 Revision Control System, which is a set of free programs used for
1213 organizing different versions and systems of files. Use the `-n' or
1214 `--rcs' option to select this output format. It is like the forward
1215 `ed' format (*note Forward ed::), but it can represent arbitrary
1216 changes to the contents of a file because it avoids the forward `ed'
1217 format's problems with lines consisting of a single period and with
1218 incomplete lines. Instead of ending text sections with a line
1219 consisting of a single period, each command specifies the number of
1220 lines it affects; a combination of the `a' and `d' commands are used
1221 instead of `c'. Also, if the second file ends in a changed incomplete
1222 line, then the output also ends in an incomplete line.
1224 Here is the output of `diff -n lao tzu' (*note Sample diff Input::,
1225 for the complete contents of the two files):
1230 The named is the mother of all things.
1233 They both may be called deep and profound.
1234 Deeper and more profound,
1235 The door of all subtleties!
1238 File: diff.info, Node: If-then-else, Prev: Scripts, Up: Output Formats
1240 Merging Files with If-then-else
1241 ===============================
1243 You can use `diff' to merge two files of C source code. The output
1244 of `diff' in this format contains all the lines of both files. Lines
1245 common to both files are output just once; the differing parts are
1246 separated by the C preprocessor directives `#ifdef NAME' or `#ifndef
1247 NAME', `#else', and `#endif'. When compiling the output, you select
1248 which version to use by either defining or leaving undefined the macro
1251 To merge two files, use `diff' with the `-D NAME' or `--ifdef=NAME'
1252 option. The argument NAME is the C preprocessor identifier to use in
1253 the `#ifdef' and `#ifndef' directives.
1255 For example, if you change an instance of `wait (&s)' to `waitpid
1256 (-1, &s, 0)' and then merge the old and new files with the
1257 `--ifdef=HAVE_WAITPID' option, then the affected part of your code
1258 might look like this:
1261 #ifndef HAVE_WAITPID
1262 if ((w = wait (&s)) < 0 && errno != EINTR)
1263 #else /* HAVE_WAITPID */
1264 if ((w = waitpid (-1, &s, 0)) < 0 && errno != EINTR)
1265 #endif /* HAVE_WAITPID */
1267 } while (w != child);
1269 You can specify formats for languages other than C by using line
1270 group formats and line formats, as described in the next sections.
1274 * Line Group Formats:: Formats for general if-then-else line groups.
1275 * Line Formats:: Formats for each line in a line group.
1276 * Detailed If-then-else:: A detailed description of if-then-else format.
1277 * Example If-then-else:: Sample if-then-else format output.
1280 File: diff.info, Node: Line Group Formats, Next: Line Formats, Up: If-then-else
1285 Line group formats let you specify formats suitable for many
1286 applications that allow if-then-else input, including programming
1287 languages and text formatting languages. A line group format specifies
1288 the output format for a contiguous group of similar lines.
1290 For example, the following command compares the TeX files `old' and
1291 `new', and outputs a merged file in which old regions are surrounded by
1292 `\begin{em}'-`\end{em}' lines, and new regions are surrounded by
1293 `\begin{bf}'-`\end{bf}' lines.
1296 --old-group-format='\begin{em}
1299 --new-group-format='\begin{bf}
1304 The following command is equivalent to the above example, but it is a
1305 little more verbose, because it spells out the default line group
1309 --old-group-format='\begin{em}
1312 --new-group-format='\begin{bf}
1315 --unchanged-group-format='%=' \
1316 --changed-group-format='\begin{em}
1323 Here is a more advanced example, which outputs a diff listing with
1324 headers containing line numbers in a "plain English" style.
1327 --unchanged-group-format='' \
1328 --old-group-format='-------- %dn line%(n=1?:s) deleted at %df:
1330 --new-group-format='-------- %dN line%(N=1?:s) added after %de:
1332 --changed-group-format='-------- %dn line%(n=1?:s) changed at %df:
1337 To specify a line group format, use `diff' with one of the options
1338 listed below. You can specify up to four line group formats, one for
1339 each kind of line group. You should quote FORMAT, because it typically
1340 contains shell metacharacters.
1342 `--old-group-format=FORMAT'
1343 These line groups are hunks containing only lines from the first
1344 file. The default old group format is the same as the changed
1345 group format if it is specified; otherwise it is a format that
1346 outputs the line group as-is.
1348 `--new-group-format=FORMAT'
1349 These line groups are hunks containing only lines from the second
1350 file. The default new group format is same as the changed group
1351 format if it is specified; otherwise it is a format that outputs
1352 the line group as-is.
1354 `--changed-group-format=FORMAT'
1355 These line groups are hunks containing lines from both files. The
1356 default changed group format is the concatenation of the old and
1359 `--unchanged-group-format=FORMAT'
1360 These line groups contain lines common to both files. The default
1361 unchanged group format is a format that outputs the line group
1364 In a line group format, ordinary characters represent themselves;
1365 conversion specifications start with `%' and have one of the following
1369 stands for the lines from the first file, including the trailing
1370 newline. Each line is formatted according to the old line format
1371 (*note Line Formats::).
1374 stands for the lines from the second file, including the trailing
1375 newline. Each line is formatted according to the new line format.
1378 stands for the lines common to both files, including the trailing
1379 newline. Each line is formatted according to the unchanged line
1386 where C is a single character, stands for C. C may not be a
1387 backslash or an apostrophe. For example, `%c':'' stands for a
1388 colon, even inside the then-part of an if-then-else format, which
1389 a colon would normally terminate.
1392 where O is a string of 1, 2, or 3 octal digits, stands for the
1393 character with octal code O. For example, `%c'\0'' stands for a
1397 where F is a `printf' conversion specification and N is one of the
1398 following letters, stands for N's value formatted with F.
1401 The line number of the line just before the group in the old
1405 The line number of the first line in the group in the old
1409 The line number of the last line in the group in the old file.
1412 The line number of the line just after the group in the old
1416 The number of lines in the group in the old file; equals L -
1420 Likewise, for lines in the new file.
1422 The `printf' conversion specification can be `%d', `%o', `%x', or
1423 `%X', specifying decimal, octal, lower case hexadecimal, or upper
1424 case hexadecimal output respectively. After the `%' the following
1425 options can appear in sequence: a series of zero or more flags; an
1426 integer specifying the minimum field width; and a period followed
1427 by an optional integer specifying the minimum number of digits.
1428 The flags are `-' for left-justification, `'' for separating the
1429 digit into groups as specified by the `LC_NUMERIC' locale category,
1430 and `0' for padding with zeros instead of spaces. For example,
1431 `%5dN' prints the number of new lines in the group in a field of
1432 width 5 characters, using the `printf' format `"%5d"'.
1435 If A equals B then T else E. A and B are each either a decimal
1436 constant or a single letter interpreted as above. This format
1437 spec is equivalent to T if A's value equals B's; otherwise it is
1440 For example, `%(N=0?no:%dN) line%(N=1?:s)' is equivalent to `no
1441 lines' if N (the number of lines in the group in the the new file)
1442 is 0, to `1 line' if N is 1, and to `%dN lines' otherwise.
1445 File: diff.info, Node: Line Formats, Next: Detailed If-then-else, Prev: Line Group Formats, Up: If-then-else
1450 Line formats control how each line taken from an input file is
1451 output as part of a line group in if-then-else format.
1453 For example, the following command outputs text with a one-character
1454 change indicator to the left of the text. The first character of output
1455 is `-' for deleted lines, `|' for added lines, and a space for
1456 unchanged lines. The formats contain newline characters where newlines
1457 are desired on output.
1460 --old-line-format='-%l
1462 --new-line-format='|%l
1464 --unchanged-line-format=' %l
1468 To specify a line format, use one of the following options. You
1469 should quote FORMAT, since it often contains shell metacharacters.
1471 `--old-line-format=FORMAT'
1472 formats lines just from the first file.
1474 `--new-line-format=FORMAT'
1475 formats lines just from the second file.
1477 `--unchanged-line-format=FORMAT'
1478 formats lines common to both files.
1480 `--line-format=FORMAT'
1481 formats all lines; in effect, it sets all three above options
1484 In a line format, ordinary characters represent themselves;
1485 conversion specifications start with `%' and have one of the following
1489 stands for the contents of the line, not counting its trailing
1490 newline (if any). This format ignores whether the line is
1491 incomplete; *Note Incomplete Lines::.
1494 stands for the contents of the line, including its trailing newline
1495 (if any). If a line is incomplete, this format preserves its
1502 where C is a single character, stands for C. C may not be a
1503 backslash or an apostrophe. For example, `%c':'' stands for a
1507 where O is a string of 1, 2, or 3 octal digits, stands for the
1508 character with octal code O. For example, `%c'\0'' stands for a
1512 where F is a `printf' conversion specification, stands for the
1513 line number formatted with F. For example, `%.5dn' prints the
1514 line number using the `printf' format `"%.5d"'. *Note Line Group
1515 Formats::, for more about printf conversion specifications.
1517 The default line format is `%l' followed by a newline character.
1519 If the input contains tab characters and it is important that they
1520 line up on output, you should ensure that `%l' or `%L' in a line format
1521 is just after a tab stop (e.g. by preceding `%l' or `%L' with a tab
1522 character), or you should use the `-t' or `--expand-tabs' option.
1524 Taken together, the line and line group formats let you specify many
1525 different formats. For example, the following command uses a format
1526 similar to normal `diff' format. You can tailor this command to get
1527 fine control over `diff' output.
1530 --old-line-format='< %l
1532 --new-line-format='> %l
1534 --old-group-format='%df%(f=l?:,%dl)d%dE
1536 --new-group-format='%dea%dF%(F=L?:,%dL)
1538 --changed-group-format='%df%(f=l?:,%dl)c%dF%(F=L?:,%dL)
1541 --unchanged-group-format='' \
1545 File: diff.info, Node: Detailed If-then-else, Next: Example If-then-else, Prev: Line Formats, Up: If-then-else
1547 Detailed Description of If-then-else Format
1548 -------------------------------------------
1550 For lines common to both files, `diff' uses the unchanged line group
1551 format. For each hunk of differences in the merged output format, if
1552 the hunk contains only lines from the first file, `diff' uses the old
1553 line group format; if the hunk contains only lines from the second
1554 file, `diff' uses the new group format; otherwise, `diff' uses the
1555 changed group format.
1557 The old, new, and unchanged line formats specify the output format of
1558 lines from the first file, lines from the second file, and lines common
1559 to both files, respectively.
1561 The option `--ifdef=NAME' is equivalent to the following sequence of
1562 options using shell syntax:
1564 --old-group-format='#ifndef NAME
1565 %<#endif /* ! NAME */
1567 --new-group-format='#ifdef NAME
1570 --unchanged-group-format='%=' \
1571 --changed-group-format='#ifndef NAME
1576 You should carefully check the `diff' output for proper nesting.
1577 For example, when using the `-D NAME' or `--ifdef=NAME' option, you
1578 should check that if the differing lines contain any of the C
1579 preprocessor directives `#ifdef', `#ifndef', `#else', `#elif', or
1580 `#endif', they are nested properly and match. If they don't, you must
1581 make corrections manually. It is a good idea to carefully check the
1582 resulting code anyway to make sure that it really does what you want it
1583 to; depending on how the input files were produced, the output might
1584 contain duplicate or otherwise incorrect code.
1586 The `patch' `-D NAME' option behaves like the `diff' `-D NAME'
1587 option, except it operates on a file and a diff to produce a merged
1588 file; *Note patch Options::.
1591 File: diff.info, Node: Example If-then-else, Prev: Detailed If-then-else, Up: If-then-else
1593 An Example of If-then-else Format
1594 ---------------------------------
1596 Here is the output of `diff -DTWO lao tzu' (*note Sample diff
1597 Input::, for the complete contents of the two files):
1600 The Way that can be told of is not the eternal Way;
1601 The name that can be named is not the eternal name.
1603 The Nameless is the origin of Heaven and Earth;
1605 The Named is the mother of all things.
1607 The named is the mother of all things.
1610 Therefore let there always be non-being,
1611 so we may see their subtlety,
1612 And let there always be being,
1613 so we may see their outcome.
1614 The two are the same,
1615 But after they are produced,
1616 they have different names.
1618 They both may be called deep and profound.
1619 Deeper and more profound,
1620 The door of all subtleties!
1624 File: diff.info, Node: Incomplete Lines, Next: Comparing Directories, Prev: Output Formats, Up: Top
1629 When an input file ends in a non-newline character, its last line is
1630 called an "incomplete line" because its last character is not a
1631 newline. All other lines are called "full lines" and end in a newline
1632 character. Incomplete lines do not match full lines unless differences
1633 in white space are ignored (*note White Space::).
1635 An incomplete line is normally distinguished on output from a full
1636 line by a following line that starts with `\'. However, the RCS format
1637 (*note RCS::) outputs the incomplete line as-is, without any trailing
1638 newline or following line. The side by side format normally represents
1639 incomplete lines as-is, but in some cases uses a `\' or `/' gutter
1640 marker; *Note Side by Side::. The if-then-else line format preserves a
1641 line's incompleteness with `%L', and discards the newline with `%l';
1642 *Note Line Formats::. Finally, with the `ed' and forward `ed' output
1643 formats (*note Output Formats::) `diff' cannot represent an incomplete
1644 line, so it pretends there was a newline and reports an error.
1646 For example, suppose `F' and `G' are one-byte files that contain
1647 just `f' and `g', respectively. Then `diff F G' outputs
1651 \ No newline at end of file
1654 \ No newline at end of file
1656 (The exact message may differ in non-English locales.) `diff -n F G'
1657 outputs the following without a trailing newline:
1663 `diff -e F G' reports two errors and outputs the following:
1670 File: diff.info, Node: Comparing Directories, Next: Adjusting Output, Prev: Incomplete Lines, Up: Top
1672 Comparing Directories
1673 *********************
1675 You can use `diff' to compare some or all of the files in two
1676 directory trees. When both file name arguments to `diff' are
1677 directories, it compares each file that is contained in both
1678 directories, examining file names in alphabetical order as specified by
1679 the `LC_COLLATE' locale category. Normally `diff' is silent about
1680 pairs of files that contain no differences, but if you use the `-s' or
1681 `--report-identical-files' option, it reports pairs of identical files.
1682 Normally `diff' reports subdirectories common to both directories
1683 without comparing subdirectories' files, but if you use the `-r' or
1684 `--recursive' option, it compares every corresponding pair of files in
1685 the directory trees, as many levels deep as they go.
1687 For file names that are in only one of the directories, `diff'
1688 normally does not show the contents of the file that exists; it reports
1689 only that the file exists in that directory and not in the other. You
1690 can make `diff' act as though the file existed but was empty in the
1691 other directory, so that it outputs the entire contents of the file that
1692 actually exists. (It is output as either an insertion or a deletion,
1693 depending on whether it is in the first or the second directory given.)
1694 To do this, use the `-N' or `--new-file' option.
1696 If the older directory contains one or more large files that are not
1697 in the newer directory, you can make the patch smaller by using the
1698 `--unidirectional-new-file' option instead of `-N'. This option is
1699 like `-N' except that it only inserts the contents of files that appear
1700 in the second directory but not the first (that is, files that were
1701 added). At the top of the patch, write instructions for the user
1702 applying the patch to remove the files that were deleted before
1703 applying the patch. *Note Making Patches::, for more discussion of
1704 making patches for distribution.
1706 To ignore some files while comparing directories, use the `-x
1707 PATTERN' or `--exclude=PATTERN' option. This option ignores any files
1708 or subdirectories whose base names match the shell pattern PATTERN.
1709 Unlike in the shell, a period at the start of the base of a file name
1710 matches a wildcard at the start of a pattern. You should enclose
1711 PATTERN in quotes so that the shell does not expand it. For example,
1712 the option `-x '*.[ao]'' ignores any file whose name ends with `.a' or
1715 This option accumulates if you specify it more than once. For
1716 example, using the options `-x 'RCS' -x '*,v'' ignores any file or
1717 subdirectory whose base name is `RCS' or ends with `,v'.
1719 If you need to give this option many times, you can instead put the
1720 patterns in a file, one pattern per line, and use the `-X FILE' or
1721 `--exclude-from=FILE' option.
1723 If you have been comparing two directories and stopped partway
1724 through, later you might want to continue where you left off. You can
1725 do this by using the `-S FILE' or `--starting-file=FILE' option. This
1726 compares only the file FILE and all alphabetically later files in the
1727 topmost directory level.
1729 If two directories differ only in that file names are lower case in
1730 one directory and upper case in the upper, `diff' normally reports many
1731 differences because it compares file names in a case sensitive way.
1732 With the `--ignore-file-name-case' option, `diff' ignores case
1733 differences in file names, so that for example the contents of the file
1734 `Tao' in one directory are compared to the contents of the file `TAO'
1735 in the other. The `--no-ignore-file-name-case' option cancels the
1736 effect of the `--ignore-file-name-case' option, reverting to the default
1739 If an `-x PATTERN', `--exclude=PATTERN', `-X FILE', or
1740 `--exclude-from=FILE' option is specified while the
1741 `--ignore-file-name-case' option is in effect, case is ignored when
1742 excluding file names matching the specified patterns.
1745 File: diff.info, Node: Adjusting Output, Next: diff Performance, Prev: Comparing Directories, Up: Top
1747 Making `diff' Output Prettier
1748 *****************************
1750 `diff' provides several ways to adjust the appearance of its output.
1751 These adjustments can be applied to any output format.
1755 * Tabs:: Preserving the alignment of tab stops.
1756 * Pagination:: Page numbering and time-stamping `diff' output.
1759 File: diff.info, Node: Tabs, Next: Pagination, Up: Adjusting Output
1761 Preserving Tab Stop Alignment
1762 =============================
1764 The lines of text in some of the `diff' output formats are preceded
1765 by one or two characters that indicate whether the text is inserted,
1766 deleted, or changed. The addition of those characters can cause tabs to
1767 move to the next tab stop, throwing off the alignment of columns in the
1768 line. GNU `diff' provides two ways to make tab-aligned columns line up
1771 The first way is to have `diff' convert all tabs into the correct
1772 number of spaces before outputting them; select this method with the
1773 `-t' or `--expand-tabs' option. `diff' assumes that tab stops are set
1774 every 8 print columns. To use this form of output with `patch', you
1775 must give `patch' the `-l' or `--ignore-white-space' option (*note
1776 Changed White Space::, for more information).
1778 The other method for making tabs line up correctly is to add a tab
1779 character instead of a space after the indicator character at the
1780 beginning of the line. This ensures that all following tab characters
1781 are in the same position relative to tab stops that they were in the
1782 original files, so that the output is aligned correctly. Its
1783 disadvantage is that it can make long lines too long to fit on one line
1784 of the screen or the paper. It also does not work with the unified
1785 output format, which does not have a space character after the change
1786 type indicator character. Select this method with the `-T' or
1787 `--initial-tab' option.
1790 File: diff.info, Node: Pagination, Prev: Tabs, Up: Adjusting Output
1792 Paginating `diff' Output
1793 ========================
1795 It can be convenient to have long output page-numbered and
1796 time-stamped. The `-l' and `--paginate' options do this by sending the
1797 `diff' output through the `pr' program. Here is what the page header
1798 might look like for `diff -lc lao tzu':
1800 2002-02-22 14:20 diff -lc lao tzu Page 1
1803 File: diff.info, Node: diff Performance, Next: Comparing Three Files, Prev: Adjusting Output, Up: Top
1805 `diff' Performance Tradeoffs
1806 ****************************
1808 GNU `diff' runs quite efficiently; however, in some circumstances
1809 you can cause it to run faster or produce a more compact set of changes.
1811 One way to improve `diff' performance is to use hard or symbolic
1812 links to files instead of copies. This improves performance because
1813 `diff' normally does not need to read two hard or symbolic links to the
1814 same file, since their contents must be identical. For example,
1815 suppose you copy a large directory hierarchy, make a few changes to the
1816 copy, and then often use `diff -r' to compare the original to the copy.
1817 If the original files are read-only, you can greatly improve
1818 performance by creating the copy using hard or symbolic links (e.g.,
1819 with GNU `cp -lR' or `cp -sR'). Before editing a file in the copy for
1820 the first time, you should break the link and replace it with a regular
1823 You can also affect the performance of GNU `diff' by giving it
1824 options that change the way it compares files. Performance has more
1825 than one dimension. These options improve one aspect of performance at
1826 the cost of another, or they improve performance in some cases while
1827 hurting it in others.
1829 The way that GNU `diff' determines which lines have changed always
1830 comes up with a near-minimal set of differences. Usually it is good
1831 enough for practical purposes. If the `diff' output is large, you
1832 might want `diff' to use a modified algorithm that sometimes produces a
1833 smaller set of differences. The `-d' or `--minimal' option does this;
1834 however, it can also cause `diff' to run more slowly than usual, so it
1835 is not the default behavior.
1837 When the files you are comparing are large and have small groups of
1838 changes scattered throughout them, you can use the
1839 `--speed-large-files' option to make a different modification to the
1840 algorithm that `diff' uses. If the input files have a constant small
1841 density of changes, this option speeds up the comparisons without
1842 changing the output. If not, `diff' might produce a larger set of
1843 differences; however, the output will still be correct.
1845 Normally `diff' discards the prefix and suffix that is common to
1846 both files before it attempts to find a minimal set of differences.
1847 This makes `diff' run faster, but occasionally it may produce
1848 non-minimal output. The `--horizon-lines=LINES' option prevents `diff'
1849 from discarding the last LINES lines of the prefix and the first LINES
1850 lines of the suffix. This gives `diff' further opportunities to find a
1853 Suppose a run of changed lines includes a sequence of lines at one
1854 end and there is an identical sequence of lines just outside the other
1855 end. The `diff' command is free to choose which identical sequence is
1856 included in the hunk. In this case, `diff' normally shifts the hunk's
1857 boundaries when this merges adjacent hunks, or shifts a hunk's lines
1858 towards the end of the file. Merging hunks can make the output look
1859 nicer in some cases.
1862 File: diff.info, Node: Comparing Three Files, Next: diff3 Merging, Prev: diff Performance, Up: Top
1864 Comparing Three Files
1865 *********************
1867 Use the program `diff3' to compare three files and show any
1868 differences among them. (`diff3' can also merge files; see *Note diff3
1871 The "normal" `diff3' output format shows each hunk of differences
1872 without surrounding context. Hunks are labeled depending on whether
1873 they are two-way or three-way, and lines are annotated by their
1874 location in the input files.
1876 *Note Invoking diff3::, for more information on how to run `diff3'.
1880 * Sample diff3 Input:: Sample `diff3' input for examples.
1881 * Detailed diff3 Normal:: A detailed description of normal output format.
1882 * diff3 Hunks:: The format of normal output format.
1883 * Example diff3 Normal:: Sample output in the normal format.
1886 File: diff.info, Node: Sample diff3 Input, Next: Detailed diff3 Normal, Up: Comparing Three Files
1888 A Third Sample Input File
1889 =========================
1891 Here is a third sample file that will be used in examples to
1892 illustrate the output of `diff3' and how various options can change it.
1893 The first two files are the same that we used for `diff' (*note Sample
1894 diff Input::). This is the third sample file, called `tao':
1896 The Way that can be told of is not the eternal Way;
1897 The name that can be named is not the eternal name.
1898 The Nameless is the origin of Heaven and Earth;
1899 The named is the mother of all things.
1901 Therefore let there always be non-being,
1902 so we may see their subtlety,
1903 And let there always be being,
1904 so we may see their result.
1905 The two are the same,
1906 But after they are produced,
1907 they have different names.
1909 -- The Way of Lao-Tzu, tr. Wing-tsit Chan
1912 File: diff.info, Node: Detailed diff3 Normal, Next: diff3 Hunks, Prev: Sample diff3 Input, Up: Comparing Three Files
1914 Detailed Description of `diff3' Normal Format
1915 =============================================
1917 Each hunk begins with a line marked `===='. Three-way hunks have
1918 plain `====' lines, and two-way hunks have `1', `2', or `3' appended to
1919 specify which of the three input files differ in that hunk. The hunks
1920 contain copies of two or three sets of input lines each preceded by one
1921 or two commands identifying where the lines came from.
1923 Normally, two spaces precede each copy of an input line to
1924 distinguish it from the commands. But with the `-T' or `--initial-tab'
1925 option, `diff3' uses a tab instead of two spaces; this lines up tabs
1926 correctly. *Note Tabs::, for more information.
1928 Commands take the following forms:
1931 This hunk appears after line L of file FILE, and contains no lines
1932 in that file. To edit this file to yield the other files, one
1933 must append hunk lines taken from the other files. For example,
1934 `1:11a' means that the hunk follows line 11 in the first file and
1935 contains no lines from that file.
1938 This hunk contains the lines in the range R of file FILE. The
1939 range R is a comma-separated pair of line numbers, or just one
1940 number if the range is a singleton. To edit this file to yield the
1941 other files, one must change the specified lines to be the lines
1942 taken from the other files. For example, `2:11,13c' means that
1943 the hunk contains lines 11 through 13 from the second file.
1945 If the last line in a set of input lines is incomplete (*note
1946 Incomplete Lines::), it is distinguished on output from a full line by
1947 a following line that starts with `\'.
1950 File: diff.info, Node: diff3 Hunks, Next: Example diff3 Normal, Prev: Detailed diff3 Normal, Up: Comparing Three Files
1955 Groups of lines that differ in two or three of the input files are
1956 called "diff3 hunks", by analogy with `diff' hunks (*note Hunks::). If
1957 all three input files differ in a `diff3' hunk, the hunk is called a
1958 "three-way hunk"; if just two input files differ, it is a "two-way
1961 As with `diff', several solutions are possible. When comparing the
1962 files `A', `B', and `C', `diff3' normally finds `diff3' hunks by
1963 merging the two-way hunks output by the two commands `diff A B' and
1964 `diff A C'. This does not necessarily minimize the size of the output,
1965 but exceptions should be rare.
1967 For example, suppose `F' contains the three lines `a', `b', `f', `G'
1968 contains the lines `g', `b', `g', and `H' contains the lines `a', `b',
1969 `h'. `diff3 F G H' might output the following:
1985 because it found a two-way hunk containing `a' in the first and third
1986 files and `g' in the second file, then the single line `b' common to
1987 all three files, then a three-way hunk containing the last line of each
1991 File: diff.info, Node: Example diff3 Normal, Prev: diff3 Hunks, Up: Comparing Three Files
1993 An Example of `diff3' Normal Format
1994 ===================================
1996 Here is the output of the command `diff3 lao tzu tao' (*note Sample
1997 diff3 Input::, for the complete contents of the files). Notice that it
1998 shows only the lines that are different among the three files.
2003 The Way that can be told of is not the eternal Way;
2004 The name that can be named is not the eternal name.
2008 The Named is the mother of all things.
2011 The named is the mother of all things.
2016 so we may see their outcome.
2018 so we may see their result.
2022 They both may be called deep and profound.
2023 Deeper and more profound,
2024 The door of all subtleties!
2027 -- The Way of Lao-Tzu, tr. Wing-tsit Chan
2030 File: diff.info, Node: diff3 Merging, Next: Interactive Merging, Prev: Comparing Three Files, Up: Top
2032 Merging From a Common Ancestor
2033 ******************************
2035 When two people have made changes to copies of the same file,
2036 `diff3' can produce a merged output that contains both sets of changes
2037 together with warnings about conflicts.
2039 One might imagine programs with names like `diff4' and `diff5' to
2040 compare more than three files simultaneously, but in practice the need
2041 rarely arises. You can use `diff3' to merge three or more sets of
2042 changes to a file by merging two change sets at a time.
2044 `diff3' can incorporate changes from two modified versions into a
2045 common preceding version. This lets you merge the sets of changes
2046 represented by the two newer files. Specify the common ancestor version
2047 as the second argument and the two newer versions as the first and third
2048 arguments, like this:
2050 diff3 MINE OLDER YOURS
2052 You can remember the order of the arguments by noting that they are in
2055 You can think of this as subtracting OLDER from YOURS and adding the
2056 result to MINE, or as merging into MINE the changes that would turn
2057 OLDER into YOURS. This merging is well-defined as long as MINE and
2058 OLDER match in the neighborhood of each such change. This fails to be
2059 true when all three input files differ or when only OLDER differs; we
2060 call this a "conflict". When all three input files differ, we call the
2061 conflict an "overlap".
2063 `diff3' gives you several ways to handle overlaps and conflicts.
2064 You can omit overlaps or conflicts, or select only overlaps, or mark
2065 conflicts with special `<<<<<<<' and `>>>>>>>' lines.
2067 `diff3' can output the merge results as an `ed' script that that can
2068 be applied to the first file to yield the merged output. However, it
2069 is usually better to have `diff3' generate the merged output directly;
2070 this bypasses some problems with `ed'.
2074 * Which Changes:: Selecting changes to incorporate.
2075 * Marking Conflicts:: Marking conflicts.
2076 * Bypassing ed:: Generating merged output directly.
2077 * Merging Incomplete Lines:: How `diff3' merges incomplete lines.
2078 * Saving the Changed File:: Emulating System V behavior.
2081 File: diff.info, Node: Which Changes, Next: Marking Conflicts, Up: diff3 Merging
2083 Selecting Which Changes to Incorporate
2084 ======================================
2086 You can select all unmerged changes from OLDER to YOURS for merging
2087 into MINE with the `-e' or `--ed' option. You can select only the
2088 nonoverlapping unmerged changes with `-3' or `--easy-only', and you can
2089 select only the overlapping changes with `-x' or `--overlap-only'.
2091 The `-e', `-3' and `-x' options select only "unmerged changes", i.e.
2092 changes where MINE and YOURS differ; they ignore changes from OLDER to
2093 YOURS where MINE and YOURS are identical, because they assume that such
2094 changes have already been merged. If this assumption is not a safe
2095 one, you can use the `-A' or `--show-all' option (*note Marking
2098 Here is the output of the command `diff3' with each of these three
2099 options (*note Sample diff3 Input::, for the complete contents of the
2100 files). Notice that `-e' outputs the union of the disjoint sets of
2101 changes output by `-3' and `-x'.
2103 Output of `diff3 -e lao tzu tao':
2106 -- The Way of Lao-Tzu, tr. Wing-tsit Chan
2109 so we may see their result.
2112 Output of `diff3 -3 lao tzu tao':
2114 so we may see their result.
2117 Output of `diff3 -x lao tzu tao':
2120 -- The Way of Lao-Tzu, tr. Wing-tsit Chan
2124 File: diff.info, Node: Marking Conflicts, Next: Bypassing ed, Prev: Which Changes, Up: diff3 Merging
2129 `diff3' can mark conflicts in the merged output by bracketing them
2130 with special marker lines. A conflict that comes from two files A and
2131 B is marked as follows:
2139 A conflict that comes from three files A, B and C is marked as
2150 The `-A' or `--show-all' option acts like the `-e' option, except
2151 that it brackets conflicts, and it outputs all changes from OLDER to
2152 YOURS, not just the unmerged changes. Thus, given the sample input
2153 files (*note Sample diff3 Input::), `diff3 -A lao tzu tao' puts
2154 brackets around the conflict where only `tzu' differs:
2158 The Way that can be told of is not the eternal Way;
2159 The name that can be named is not the eternal name.
2162 And it outputs the three-way conflict as follows:
2166 They both may be called deep and profound.
2167 Deeper and more profound,
2168 The door of all subtleties!
2171 -- The Way of Lao-Tzu, tr. Wing-tsit Chan
2174 The `-E' or `--show-overlap' option outputs less information than
2175 the `-A' or `--show-all' option, because it outputs only unmerged
2176 changes, and it never outputs the contents of the second file. Thus
2177 the `-E' option acts like the `-e' option, except that it brackets the
2178 first and third files from three-way overlapping changes. Similarly,
2179 `-X' acts like `-x', except it brackets all its (necessarily
2180 overlapping) changes. For example, for the three-way overlapping
2181 change above, the `-E' and `-X' options output the following:
2186 -- The Way of Lao-Tzu, tr. Wing-tsit Chan
2189 If you are comparing files that have meaningless or uninformative
2190 names, you can use the `-L LABEL' or `--label=LABEL' option to show
2191 alternate names in the `<<<<<<<', `|||||||' and `>>>>>>>' brackets.
2192 This option can be given up to three times, once for each input file.
2193 Thus `diff3 -A -L X -L Y -L Z A B C' acts like `diff3 -A A B C', except
2194 that the output looks like it came from files named `X', `Y' and `Z'
2195 rather than from files named `A', `B' and `C'.
2198 File: diff.info, Node: Bypassing ed, Next: Merging Incomplete Lines, Prev: Marking Conflicts, Up: diff3 Merging
2200 Generating the Merged Output Directly
2201 =====================================
2203 With the `-m' or `--merge' option, `diff3' outputs the merged file
2204 directly. This is more efficient than using `ed' to generate it, and
2205 works even with non-text files that `ed' would reject. If you specify
2206 `-m' without an `ed' script option, `-A' (`--show-all') is assumed.
2208 For example, the command `diff3 -m lao tzu tao' (*note Sample diff3
2209 Input:: for a copy of the input files) would output the following:
2213 The Way that can be told of is not the eternal Way;
2214 The name that can be named is not the eternal name.
2216 The Nameless is the origin of Heaven and Earth;
2217 The Named is the mother of all things.
2218 Therefore let there always be non-being,
2219 so we may see their subtlety,
2220 And let there always be being,
2221 so we may see their result.
2222 The two are the same,
2223 But after they are produced,
2224 they have different names.
2227 They both may be called deep and profound.
2228 Deeper and more profound,
2229 The door of all subtleties!
2232 -- The Way of Lao-Tzu, tr. Wing-tsit Chan
2236 File: diff.info, Node: Merging Incomplete Lines, Next: Saving the Changed File, Prev: Bypassing ed, Up: diff3 Merging
2238 How `diff3' Merges Incomplete Lines
2239 ===================================
2241 With `-m', incomplete lines (*note Incomplete Lines::) are simply
2242 copied to the output as they are found; if the merged output ends in an
2243 conflict and one of the input files ends in an incomplete line,
2244 succeeding `|||||||', `=======' or `>>>>>>>' brackets appear somewhere
2245 other than the start of a line because they are appended to the
2248 Without `-m', if an `ed' script option is specified and an
2249 incomplete line is found, `diff3' generates a warning and acts as if a
2250 newline had been present.
2253 File: diff.info, Node: Saving the Changed File, Prev: Merging Incomplete Lines, Up: diff3 Merging
2255 Saving the Changed File
2256 =======================
2258 Traditional Unix `diff3' generates an `ed' script without the
2259 trailing `w' and `q' commands that save the changes. System V `diff3'
2260 generates these extra commands. GNU `diff3' normally behaves like
2261 traditional Unix `diff3', but with the `-i' option it behaves like
2262 System V `diff3' and appends the `w' and `q' commands.
2264 The `-i' option requires one of the `ed' script options `-AeExX3',
2265 and is incompatible with the merged output option `-m'.
2268 File: diff.info, Node: Interactive Merging, Next: Merging with patch, Prev: diff3 Merging, Up: Top
2270 Interactive Merging with `sdiff'
2271 ********************************
2273 With `sdiff', you can merge two files interactively based on a
2274 side-by-side `-y' format comparison (*note Side by Side::). Use `-o
2275 FILE' or `--output=FILE' to specify where to put the merged text.
2276 *Note Invoking sdiff::, for more details on the options to `sdiff'.
2278 Another way to merge files interactively is to use the Emacs Lisp
2279 package `emerge'. *Note emerge: (emacs)emerge, for more information.
2283 * sdiff Option Summary:: Summary of `sdiff' options.
2284 * Merge Commands:: Merging two files interactively.
2287 File: diff.info, Node: sdiff Option Summary, Next: Merge Commands, Up: Interactive Merging
2289 Specifying `diff' Options to `sdiff'
2290 ====================================
2292 The following `sdiff' options have the same meaning as for `diff'.
2293 *Note diff Options::, for the use of these options.
2298 --ignore-blank-lines --ignore-case
2299 --ignore-matching-lines=REGEXP --ignore-space-change
2300 --ignore-tab-expansion
2301 --left-column --minimal --speed-large-files
2302 --strip-trailing-cr --suppress-common-lines --expand-tabs
2303 --text --version --width=COLUMNS
2305 For historical reasons, `sdiff' has alternate names for some
2306 options. The `-l' option is equivalent to the `--left-column' option,
2307 and similarly `-s' is equivalent to `--suppress-common-lines'. The
2308 meaning of the `sdiff' `-w' and `-W' options is interchanged from that
2309 of `diff': with `sdiff', `-w COLUMNS' is equivalent to
2310 `--width=COLUMNS', and `-W' is equivalent to `--ignore-all-space'.
2311 `sdiff' without the `-o' option is equivalent to `diff' with the `-y'
2312 or `--side-by-side' option (*note Side by Side::).
2315 File: diff.info, Node: Merge Commands, Prev: sdiff Option Summary, Up: Interactive Merging
2320 Groups of common lines, with a blank gutter, are copied from the
2321 first file to the output. After each group of differing lines, `sdiff'
2322 prompts with `%' and pauses, waiting for one of the following commands.
2323 Follow each command with <RET>.
2326 Discard both versions. Invoke a text editor on an empty temporary
2327 file, then copy the resulting file to the output.
2330 Concatenate the two versions, edit the result in a temporary file,
2331 then copy the edited result to the output.
2334 Like `eb', except precede each version with a header that shows
2335 what file and lines the version came from.
2338 Edit a copy of the left version, then copy the result to the
2342 Edit a copy of the right version, then copy the result to the
2346 Copy the left version to the output.
2352 Copy the right version to the output.
2355 Silently copy common lines.
2358 Verbosely copy common lines. This is the default.
2360 The text editor invoked is specified by the `EDITOR' environment
2361 variable if it is set. The default is system-dependent.
2364 File: diff.info, Node: Merging with patch, Next: Making Patches, Prev: Interactive Merging, Up: Top
2366 Merging with `patch'
2367 ********************
2369 `patch' takes comparison output produced by `diff' and applies the
2370 differences to a copy of the original file, producing a patched
2371 version. With `patch', you can distribute just the changes to a set of
2372 files instead of distributing the entire file set; your correspondents
2373 can apply `patch' to update their copy of the files with your changes.
2374 `patch' automatically determines the diff format, skips any leading or
2375 trailing headers, and uses the headers to determine which file to
2376 patch. This lets your correspondents feed a mail message containing a
2377 difference listing directly to `patch'.
2379 `patch' detects and warns about common problems like forward
2380 patches. It saves any patches that it could not apply. It can also
2381 maintain a `patchlevel.h' file to ensure that your correspondents apply
2382 diffs in the proper order.
2384 `patch' accepts a series of diffs in its standard input, usually
2385 separated by headers that specify which file to patch. It applies
2386 `diff' hunks (*note Hunks::) one by one. If a hunk does not exactly
2387 match the original file, `patch' uses heuristics to try to patch the
2388 file as well as it can. If no approximate match can be found, `patch'
2389 rejects the hunk and skips to the next hunk. `patch' normally replaces
2390 each file F with its new version, putting reject hunks (if any) into
2393 *Note Invoking patch::, for detailed information on the options to
2398 * patch Input:: Selecting the type of `patch' input.
2399 * Revision Control:: Getting files from RCS, SCCS, etc.
2400 * Imperfect:: Dealing with imperfect patches.
2401 * Creating and Removing:: Creating and removing files with a patch.
2402 * Patching Time Stamps:: Updating time stamps on patched files.
2403 * Multiple Patches:: Handling multiple patches in a file.
2404 * patch Directories:: Changing directory and stripping directories.
2405 * Backups:: Whether backup files are made.
2406 * Backup Names:: Backup file names.
2407 * Reject Names:: Reject file names.
2408 * patch Messages:: Messages and questions `patch' can produce.
2409 * patch and POSIX:: Conformance to the POSIX standard.
2410 * patch and Tradition:: GNU versus traditional `patch'.
2413 File: diff.info, Node: patch Input, Next: Revision Control, Up: Merging with patch
2415 Selecting the `patch' Input Format
2416 ==================================
2418 `patch' normally determines which `diff' format the patch file uses
2419 by examining its contents. For patch files that contain particularly
2420 confusing leading text, you might need to use one of the following
2421 options to force `patch' to interpret the patch file as a certain
2422 format of diff. The output formats listed here are the only ones that
2423 `patch' can understand.
2442 File: diff.info, Node: Revision Control, Next: Imperfect, Prev: patch Input, Up: Merging with patch
2447 If a nonexistent input file is under a revision control system
2448 supported by `patch', `patch' normally asks the user whether to get (or
2449 check out) the file from the revision control system. Patch currently
2450 supports RCS, ClearCase and SCCS. Under RCS and SCCS, `patch' also
2451 asks when the input file is read-only and matches the default version
2452 in the revision control system.
2454 The `-g NUM' or `--get=NUM' affects access to files under supported
2455 revision control systems. If NUM is positive, `patch' gets the file
2456 without asking the user; if zero, `patch' neither asks the user nor
2457 gets the file; and if negative, `patch' asks the user before getting
2458 the file. The default value of NUM is given by the value of the
2459 `PATCH_GET' environment variable if it is set; if not, the default
2460 value is zero if `patch' is conforming to POSIX, negative otherwise.
2461 *Note patch and POSIX::.
2463 The choice of revision control system is unaffected by the
2464 `VERSION_CONTROL' environment variable (*note Backup Names::).
2467 File: diff.info, Node: Imperfect, Next: Creating and Removing, Prev: Revision Control, Up: Merging with patch
2469 Applying Imperfect Patches
2470 ==========================
2472 `patch' tries to skip any leading text in the patch file, apply the
2473 diff, and then skip any trailing text. Thus you can feed a mail
2474 message directly to `patch', and it should work. If the entire diff is
2475 indented by a constant amount of white space, `patch' automatically
2476 ignores the indentation. If a context diff contains trailing carriage
2477 return on each line, `patch' automatically ignores the carriage return.
2478 If a context diff has been encapsulated by prepending `- ' to lines
2479 beginning with `-' as per Internet RFC 934
2480 (ftp://ftp.isi.edu/in-notes/rfc934.txt), `patch' automatically
2481 unencapsulates the input.
2483 However, certain other types of imperfect input require user
2484 intervention or testing.
2488 * Changed White Space:: When tabs and spaces don't match exactly.
2489 * Reversed Patches:: Applying reversed patches correctly.
2490 * Inexact:: Helping `patch' find close matches.
2491 * Dry Runs:: Predicting what `patch' will do.
2494 File: diff.info, Node: Changed White Space, Next: Reversed Patches, Up: Imperfect
2496 Applying Patches with Changed White Space
2497 -----------------------------------------
2499 Sometimes mailers, editors, or other programs change spaces into
2500 tabs, or vice versa. If this happens to a patch file or an input file,
2501 the files might look the same, but `patch' will not be able to match
2502 them properly. If this problem occurs, use the `-l' or
2503 `--ignore-white-space' option, which makes `patch' compare blank
2504 characters (i.e. spaces and tabs) loosely so that any nonempty sequence
2505 of blanks in the patch file matches any nonempty sequence of blanks in
2506 the input files. Non-blank characters must still match exactly. Each
2507 line of the context must still match a line in the input file.
2510 File: diff.info, Node: Reversed Patches, Next: Inexact, Prev: Changed White Space, Up: Imperfect
2512 Applying Reversed Patches
2513 -------------------------
2515 Sometimes people run `diff' with the new file first instead of
2516 second. This creates a diff that is "reversed". To apply such
2517 patches, give `patch' the `-R' or `--reverse' option. `patch' then
2518 attempts to swap each hunk around before applying it. Rejects come out
2519 in the swapped format.
2521 Often `patch' can guess that the patch is reversed. If the first
2522 hunk of a patch fails, `patch' reverses the hunk to see if it can apply
2523 it that way. If it can, `patch' asks you if you want to have the `-R'
2524 option set; if it can't, `patch' continues to apply the patch normally.
2525 This method cannot detect a reversed patch if it is a normal diff and
2526 the first command is an append (which should have been a delete) since
2527 appends always succeed, because a null context matches anywhere. But
2528 most patches add or change lines rather than delete them, so most
2529 reversed normal diffs begin with a delete, which fails, and `patch'
2532 If you apply a patch that you have already applied, `patch' thinks
2533 it is a reversed patch and offers to un-apply the patch. This could be
2534 construed as a feature. If you did this inadvertently and you don't
2535 want to un-apply the patch, just answer `n' to this offer and to the
2536 subsequent "apply anyway" question--or type `C-c' to kill the `patch'
2540 File: diff.info, Node: Inexact, Next: Dry Runs, Prev: Reversed Patches, Up: Imperfect
2542 Helping `patch' Find Inexact Matches
2543 ------------------------------------
2545 For context diffs, and to a lesser extent normal diffs, `patch' can
2546 detect when the line numbers mentioned in the patch are incorrect, and
2547 it attempts to find the correct place to apply each hunk of the patch.
2548 As a first guess, it takes the line number mentioned in the hunk, plus
2549 or minus any offset used in applying the previous hunk. If that is not
2550 the correct place, `patch' scans both forward and backward for a set of
2551 lines matching the context given in the hunk.
2553 First `patch' looks for a place where all lines of the context
2554 match. If it cannot find such a place, and it is reading a context or
2555 unified diff, and the maximum fuzz factor is set to 1 or more, then
2556 `patch' makes another scan, ignoring the first and last line of
2557 context. If that fails, and the maximum fuzz factor is set to 2 or
2558 more, it makes another scan, ignoring the first two and last two lines
2559 of context are ignored. It continues similarly if the maximum fuzz
2562 The `-F LINES' or `--fuzz=LINES' option sets the maximum fuzz factor
2563 to LINES. This option only applies to context and unified diffs; it
2564 ignores up to LINES lines while looking for the place to install a
2565 hunk. Note that a larger fuzz factor increases the odds of making a
2566 faulty patch. The default fuzz factor is 2; there is no point to
2567 setting it to more than the number of lines of context in the diff,
2570 If `patch' cannot find a place to install a hunk of the patch, it
2571 writes the hunk out to a reject file (*note Reject Names::, for
2572 information on how reject files are named). It writes out rejected
2573 hunks in context format no matter what form the input patch is in. If
2574 the input is a normal or `ed' diff, many of the contexts are simply
2575 null. The line numbers on the hunks in the reject file may be
2576 different from those in the patch file: they show the approximate
2577 location where `patch' thinks the failed hunks belong in the new file
2578 rather than in the old one.
2580 If the `--verbose' option is given, then as it completes each hunk
2581 `patch' tells you whether the hunk succeeded or failed, and if it
2582 failed, on which line (in the new file) `patch' thinks the hunk should
2583 go. If this is different from the line number specified in the diff,
2584 it tells you the offset. A single large offset _may_ indicate that
2585 `patch' installed a hunk in the wrong place. `patch' also tells you if
2586 it used a fuzz factor to make the match, in which case you should also
2587 be slightly suspicious.
2589 `patch' cannot tell if the line numbers are off in an `ed' script,
2590 and can only detect wrong line numbers in a normal diff when it finds a
2591 change or delete command. It may have the same problem with a context
2592 diff using a fuzz factor equal to or greater than the number of lines
2593 of context shown in the diff (typically 3). In these cases, you should
2594 probably look at a context diff between your original and patched input
2595 files to see if the changes make sense. Compiling without errors is a
2596 pretty good indication that the patch worked, but not a guarantee.
2598 A patch against an empty file applies to a nonexistent file, and vice
2599 versa. *Note Creating and Removing::.
2601 `patch' usually produces the correct results, even when it must make
2602 many guesses. However, the results are guaranteed only when the patch
2603 is applied to an exact copy of the file that the patch was generated
2607 File: diff.info, Node: Dry Runs, Prev: Inexact, Up: Imperfect
2609 Predicting what `patch' will do
2610 -------------------------------
2612 It may not be obvious in advance what `patch' will do with a
2613 complicated or poorly formatted patch. If you are concerned that the
2614 input might cause `patch' to modify the wrong files, you can use the
2615 `--dry-run' option, which causes `patch' to print the results of
2616 applying patches without actually changing any files. You can then
2617 inspect the diagnostics generated by the dry run to see whether `patch'
2618 will modify the files that you expect. If the patch does not do what
2619 you want, you can modify the patch (or the other options to `patch')
2620 and try another dry run. Once you are satisfied with the proposed
2621 patch you can apply it by invoking `patch' as before, but this time
2622 without the `--dry-run' option.
2625 File: diff.info, Node: Creating and Removing, Next: Patching Time Stamps, Prev: Imperfect, Up: Merging with patch
2627 Creating and Removing Files
2628 ===========================
2630 Sometimes when comparing two directories, a file may exist in one
2631 directory but not the other. If you give `diff' the `-N' or
2632 `--new-file' option, or if you supply an old or new file that is named
2633 `/dev/null' or is empty and is dated the Epoch (1970-01-01 00:00:00
2634 UTC), `diff' outputs a patch that adds or deletes the contents of this
2635 file. When given such a patch, `patch' normally creates a new file or
2636 removes the old file. However, when conforming to POSIX (*note patch
2637 and POSIX::), `patch' does not remove the old file, but leaves it empty.
2638 The `-E' or `--remove-empty-files' option causes `patch' to remove
2639 output files that are empty after applying a patch, even if the patch
2640 does not appear to be one that removed the file.
2642 If the patch appears to create a file that already exists, `patch'
2643 asks for confirmation before applying the patch.
2646 File: diff.info, Node: Patching Time Stamps, Next: Multiple Patches, Prev: Creating and Removing, Up: Merging with patch
2648 Updating Time Stamps on Patched Files
2649 =====================================
2651 When `patch' updates a file, it normally sets the file's
2652 last-modified time stamp to the current time of day. If you are using
2653 `patch' to track a software distribution, this can cause `make' to
2654 incorrectly conclude that a patched file is out of date. For example,
2655 if `syntax.c' depends on `syntax.y', and `patch' updates `syntax.c' and
2656 then `syntax.y', then `syntax.c' will normally appear to be out of date
2657 with respect to `syntax.y' even though its contents are actually up to
2660 The `-Z' or `--set-utc' option causes `patch' to set a patched
2661 file's modification and access times to the time stamps given in
2662 context diff headers. If the context diff headers do not specify a
2663 time zone, they are assumed to use Coordinated Universal Time (UTC,
2664 often known as GMT).
2666 The `-T' or `--set-time' option acts like `-Z' or `--set-utc',
2667 except that it assumes that the context diff headers' time stamps use
2668 local time instead of UTC. This option is not recommended, because
2669 patches using local time cannot easily be used by people in other time
2670 zones, and because local time stamps are ambiguous when local clocks
2671 move backwards during daylight-saving time adjustments. If the context
2672 diff headers specify a time zone, this option is equivalent to `-Z' or
2675 `patch' normally refrains from setting a file's time stamps if the
2676 file's original last-modified time stamp does not match the time given
2677 in the diff header, of if the file's contents do not exactly match the
2678 patch. However, if the `-f' or `--force' option is given, the file's
2679 time stamps are set regardless.
2681 Due to the limitations of the current `diff' format, `patch' cannot
2682 update the times of files whose contents have not changed. Also, if
2683 you set file time stamps to values other than the current time of day,
2684 you should also remove (e.g., with `make clean') all files that depend
2685 on the patched files, so that later invocations of `make' do not get
2686 confused by the patched files' times.
2689 File: diff.info, Node: Multiple Patches, Next: patch Directories, Prev: Patching Time Stamps, Up: Merging with patch
2691 Multiple Patches in a File
2692 ==========================
2694 If the patch file contains more than one patch, and if you do not
2695 specify an input file on the command line, `patch' tries to apply each
2696 patch as if they came from separate patch files. This means that it
2697 determines the name of the file to patch for each patch, and that it
2698 examines the leading text before each patch for file names and
2699 prerequisite revision level (*note Making Patches::, for more on that
2702 `patch' uses the following rules to intuit a file name from the
2703 leading text before a patch. First, `patch' takes an ordered list of
2704 candidate file names as follows:
2706 * If the header is that of a context diff, `patch' takes the old and
2707 new file names in the header. A name is ignored if it does not
2708 have enough slashes to satisfy the `-pNUM' or `--strip=NUM'
2709 option. The name `/dev/null' is also ignored.
2711 * If there is an `Index:' line in the leading garbage and if either
2712 the old and new names are both absent or if `patch' is conforming
2713 to POSIX, `patch' takes the name in the `Index:' line.
2715 * For the purpose of the following rules, the candidate file names
2716 are considered to be in the order (old, new, index), regardless of
2717 the order that they appear in the header.
2719 Then `patch' selects a file name from the candidate list as follows:
2721 * If some of the named files exist, `patch' selects the first name
2722 if conforming to POSIX, and the best name otherwise.
2724 * If `patch' is not ignoring RCS, ClearCase, and SCCS (*note
2725 Revision Control::), and no named files exist but an RCS,
2726 ClearCase, or SCCS master is found, `patch' selects the first
2727 named file with an RCS, ClearCase, or SCCS master.
2729 * If no named files exist, no RCS, ClearCase, or SCCS master was
2730 found, some names are given, `patch' is not conforming to POSIX,
2731 and the patch appears to create a file, `patch' selects the best
2732 name requiring the creation of the fewest directories.
2734 * If no file name results from the above heuristics, you are asked
2735 for the name of the file to patch, and `patch' selects that name.
2737 To determine the "best" of a nonempty list of file names, `patch'
2738 first takes all the names with the fewest path name components; of
2739 those, it then takes all the names with the shortest basename; of
2740 those, it then takes all the shortest names; finally, it takes the
2741 first remaining name.
2743 *Note patch and POSIX::, to see whether `patch' is conforming to
2747 File: diff.info, Node: patch Directories, Next: Backups, Prev: Multiple Patches, Up: Merging with patch
2749 Applying Patches in Other Directories
2750 =====================================
2752 The `-d DIRECTORY' or `--directory=DIRECTORY' option to `patch'
2753 makes directory DIRECTORY the current directory for interpreting both
2754 file names in the patch file, and file names given as arguments to
2755 other options (such as `-B' and `-o'). For example, while in a mail
2756 reading program, you can patch a file in the `/usr/src/emacs' directory
2757 directly from a message containing the patch like this:
2759 | patch -d /usr/src/emacs
2761 Sometimes the file names given in a patch contain leading
2762 directories, but you keep your files in a directory different from the
2763 one given in the patch. In those cases, you can use the `-pNUMBER' or
2764 `--strip=NUMBER' option to set the file name strip count to NUMBER.
2765 The strip count tells `patch' how many slashes, along with the directory
2766 names between them, to strip from the front of file names. A sequence
2767 of one or more adjacent slashes is counted as a single slash. By
2768 default, `patch' strips off all leading directories, leaving just the
2771 For example, suppose the file name in the patch file is
2772 `/gnu/src/emacs/etc/NEWS'. Using `-p0' gives the entire file name
2773 unmodified, `-p1' gives `gnu/src/emacs/etc/NEWS' (no leading slash),
2774 `-p4' gives `etc/NEWS', and not specifying `-p' at all gives `NEWS'.
2776 `patch' looks for each file (after any slashes have been stripped)
2777 in the current directory, or if you used the `-d DIRECTORY' option, in
2781 File: diff.info, Node: Backups, Next: Backup Names, Prev: patch Directories, Up: Merging with patch
2786 Normally, `patch' creates a backup file if the patch does not
2787 exactly match the original input file, because in that case the
2788 original data might not be recovered if you undo the patch with `patch
2789 -R' (*note Reversed Patches::). However, when conforming to POSIX,
2790 `patch' does not create backup files by default. *Note patch and
2793 The `-b' or `--backup' option causes `patch' to make a backup file
2794 regardless of whether the patch matches the original input. The
2795 `--backup-if-mismatch' option causes `patch' to create backup files for
2796 mismatches files; this is the default when not conforming to POSIX. The
2797 `--no-backup-if-mismatch' option causes `patch' to not create backup
2798 files, even for mismatched patches; this is the default when conforming
2801 When backing up a file that does not exist, an empty, unreadable
2802 backup file is created as a placeholder to represent the nonexistent
2806 File: diff.info, Node: Backup Names, Next: Reject Names, Prev: Backups, Up: Merging with patch
2811 Normally, `patch' renames an original input file into a backup file
2812 by appending to its name the extension `.orig', or `~' if using `.orig'
2813 would make the backup file name too long.(1) The `-z BACKUP-SUFFIX' or
2814 `--suffix=BACKUP-SUFFIX' option causes `patch' to use BACKUP-SUFFIX as
2815 the backup extension instead.
2817 Alternately, you can specify the extension for backup files with the
2818 `SIMPLE_BACKUP_SUFFIX' environment variable, which the options override.
2820 `patch' can also create numbered backup files the way GNU Emacs
2821 does. With this method, instead of having a single backup of each file,
2822 `patch' makes a new backup file name each time it patches a file. For
2823 example, the backups of a file named `sink' would be called,
2824 successively, `sink.~1~', `sink.~2~', `sink.~3~', etc.
2826 The `-V BACKUP-STYLE' or `--version-control=BACKUP-STYLE' option
2827 takes as an argument a method for creating backup file names. You can
2828 alternately control the type of backups that `patch' makes with the
2829 `PATCH_VERSION_CONTROL' environment variable, which the `-V' option
2830 overrides. If `PATCH_VERSION_CONTROL' is not set, the
2831 `VERSION_CONTROL' environment variable is used instead. Please note
2832 that these options and variables control backup file names; they do not
2833 affect the choice of revision control system (*note Revision Control::).
2835 The values of these environment variables and the argument to the
2836 `-V' option are like the GNU Emacs `version-control' variable (*note
2837 Backup Names: (emacs)Backup Names., for more information on backup
2838 versions in Emacs). They also recognize synonyms that are more
2839 descriptive. The valid values are listed below; unique abbreviations
2844 Always make numbered backups.
2848 Make numbered backups of files that already have them, simple
2849 backups of the others. This is the default.
2853 Always make simple backups.
2855 You can also tell `patch' to prepend a prefix, such as a directory
2856 name, to produce backup file names. The `-B PREFIX' or
2857 `--prefix=PREFIX' option makes backup files by prepending PREFIX to
2858 them. The `-Y PREFIX' or `--basename-prefix=PREFIX' prepends PREFIX to
2859 the last file name component of backup file names instead; for example,
2860 `-Y ~' causes the backup name for `dir/file.c' to be `dir/~file.c'. If
2861 you use either of these prefix options, the suffix-based options are
2864 If you specify the output file with the `-o' option, that file is
2865 the one that is backed up, not the input file.
2867 Options that affect the names of backup files do not affect whether
2868 backups are made. For example, if you specify the
2869 `--no-backup-if-mismatch' option, none of the options described in this
2870 section have any affect, because no backups are made.
2872 ---------- Footnotes ----------
2874 (1) A coding error in GNU `patch' version 2.5.4 causes it to always
2875 use `~', but this should be fixed in the next release.
2878 File: diff.info, Node: Reject Names, Next: patch Messages, Prev: Backup Names, Up: Merging with patch
2883 The names for reject files (files containing patches that `patch'
2884 could not find a place to apply) are normally the name of the output
2885 file with `.rej' appended (or `#' if if using `.rej' would make the
2886 backup file name too long).
2888 Alternatively, you can tell `patch' to place all of the rejected
2889 patches in a single file. The `-r REJECT-FILE' or
2890 `--reject-file=REJECT-FILE' option uses REJECT-FILE as the reject file
2894 File: diff.info, Node: patch Messages, Next: patch and POSIX, Prev: Reject Names, Up: Merging with patch
2896 Messages and Questions from `patch'
2897 ===================================
2899 `patch' can produce a variety of messages, especially if it has
2900 trouble decoding its input. In a few situations where it's not sure
2901 how to proceed, `patch' normally prompts you for more information from
2902 the keyboard. There are options to produce more or fewer messages, to
2903 have it not ask for keyboard input, and to affect the way that file
2904 names are quoted in messages.
2908 * More or Fewer Messages:: Controlling the verbosity of `patch'.
2909 * patch and Keyboard Input:: Inhibiting keyboard input.
2910 * patch Quoting Style:: Quoting file names in diagnostics.
2912 `patch' exits with status 0 if all hunks are applied successfully, 1
2913 if some hunks cannot be applied, and 2 if there is more serious trouble.
2914 When applying a set of patches in a loop, you should check the exit
2915 status, so you don't apply a later patch to a partially patched file.
2918 File: diff.info, Node: More or Fewer Messages, Next: patch and Keyboard Input, Up: patch Messages
2920 Controlling the Verbosity of `patch'
2921 ------------------------------------
2923 You can cause `patch' to produce more messages by using the
2924 `--verbose' option. For example, when you give this option, the
2925 message `Hmm...' indicates that `patch' is reading text in the patch
2926 file, attempting to determine whether there is a patch in that text,
2927 and if so, what kind of patch it is.
2929 You can inhibit all terminal output from `patch', unless an error
2930 occurs, by using the `-s', `--quiet', or `--silent' option.
2933 File: diff.info, Node: patch and Keyboard Input, Next: patch Quoting Style, Prev: More or Fewer Messages, Up: patch Messages
2935 Inhibiting Keyboard Input
2936 -------------------------
2938 There are two ways you can prevent `patch' from asking you any
2939 questions. The `-f' or `--force' option assumes that you know what you
2940 are doing. It causes `patch' to do the following:
2942 * Skip patches that do not contain file names in their headers.
2944 * Patch files even though they have the wrong version for the
2945 `Prereq:' line in the patch;
2947 * Assume that patches are not reversed even if they look like they
2950 The `-t' or `--batch' option is similar to `-f', in that it suppresses
2951 questions, but it makes somewhat different assumptions:
2953 * Skip patches that do not contain file names in their headers (the
2956 * Skip patches for which the file has the wrong version for the
2957 `Prereq:' line in the patch;
2959 * Assume that patches are reversed if they look like they are.
2962 File: diff.info, Node: patch Quoting Style, Prev: patch and Keyboard Input, Up: patch Messages
2964 `patch' Quoting Style
2965 ---------------------
2967 When `patch' outputs a file name in a diagnostic message, it can
2968 format the name in any of several ways. This can be useful to output
2969 file names unambiguously, even if they contain punctuation or special
2970 characters like newlines. The `--quoting-style=WORD' option controls
2971 how names are output. The WORD should be one of the following:
2977 Quote names for the shell if they contain shell metacharacters or
2978 would cause ambiguous output.
2981 Quote names for the shell, even if they would normally not require
2985 Quote names as for a C language string.
2988 Quote as with `c' except omit the surrounding double-quote
2991 You can specify the default value of the `--quoting-style' option
2992 with the environment variable `QUOTING_STYLE'. If that environment
2993 variable is not set, the default value is `shell', but this default may
2994 change in a future version of `patch'.
2997 File: diff.info, Node: patch and POSIX, Next: patch and Tradition, Prev: patch Messages, Up: Merging with patch
2999 `patch' and the POSIX Standard
3000 ==============================
3002 If you specify the `--posix' option, or set the `POSIXLY_CORRECT'
3003 environment variable, `patch' conforms more strictly to the POSIX
3004 standard, as follows:
3006 * Take the first existing file from the list (old, new, index) when
3007 intuiting file names from diff headers. *Note Multiple Patches::.
3009 * Do not remove files that are removed by a diff. *Note Creating
3012 * Do not ask whether to get files from RCS, ClearCase, or SCCS.
3013 *Note Revision Control::.
3015 * Require that all options precede the files in the command line.
3017 * Do not backup files, even when there is a mismatch. *Note
3022 File: diff.info, Node: patch and Tradition, Prev: patch and POSIX, Up: Merging with patch
3024 GNU `patch' and Traditional `patch'
3025 ===================================
3027 The current version of GNU `patch' normally follows the POSIX
3028 standard. *Note patch and POSIX::, for the few exceptions to this
3031 Unfortunately, POSIX redefined the behavior of `patch' in several
3032 important ways. You should be aware of the following differences if
3033 you must interoperate with traditional `patch', or with GNU `patch'
3034 version 2.1 and earlier.
3036 * In traditional `patch', the `-p' option's operand was optional,
3037 and a bare `-p' was equivalent to `-p0'. The `-p' option now
3038 requires an operand, and `-p 0' is now equivalent to `-p0'. For
3039 maximum compatibility, use options like `-p0' and `-p1'.
3041 Also, traditional `patch' simply counted slashes when stripping
3042 path prefixes; `patch' now counts pathname components. That is, a
3043 sequence of one or more adjacent slashes now counts as a single
3044 slash. For maximum portability, avoid sending patches containing
3047 * In traditional `patch', backups were enabled by default. This
3048 behavior is now enabled with the `-b' or `--backup' option.
3050 Conversely, in POSIX `patch', backups are never made, even when
3051 there is a mismatch. In GNU `patch', this behavior is enabled
3052 with the `--no-backup-if-mismatch' option, or by conforming to
3055 The `-b SUFFIX' option of traditional `patch' is equivalent to the
3056 `-b -z SUFFIX' options of GNU `patch'.
3058 * Traditional `patch' used a complicated (and incompletely
3059 documented) method to intuit the name of the file to be patched
3060 from the patch header. This method did not conform to POSIX, and
3061 had a few gotchas. Now `patch' uses a different, equally
3062 complicated (but better documented) method that is optionally
3063 POSIX-conforming; we hope it has fewer gotchas. The two methods
3064 are compatible if the file names in the context diff header and the
3065 `Index:' line are all identical after prefix-stripping. Your
3066 patch is normally compatible if each header's file names all
3067 contain the same number of slashes.
3069 * When traditional `patch' asked the user a question, it sent the
3070 question to standard error and looked for an answer from the first
3071 file in the following list that was a terminal: standard error,
3072 standard output, `/dev/tty', and standard input. Now `patch'
3073 sends questions to standard output and gets answers from
3074 `/dev/tty'. Defaults for some answers have been changed so that
3075 `patch' never goes into an infinite loop when using default
3078 * Traditional `patch' exited with a status value that counted the
3079 number of bad hunks, or with status 1 if there was real trouble.
3080 Now `patch' exits with status 1 if some hunks failed, or with 2 if
3081 there was real trouble.
3083 * Limit yourself to the following options when sending instructions
3084 meant to be executed by anyone running GNU `patch', traditional
3085 `patch', or a `patch' that conforms to POSIX. Spaces are
3086 significant in the following list, and operands are required.
3102 File: diff.info, Node: Making Patches, Next: Invoking cmp, Prev: Merging with patch, Up: Top
3104 Tips for Making and Using Patches
3105 *********************************
3107 Use some common sense when making and using patches. For example,
3108 when sending bug fixes to a program's maintainer, send several small
3109 patches, one per independent subject, instead of one large,
3110 harder-to-digest patch that covers all the subjects.
3112 Here are some other things you should keep in mind if you are going
3113 to distribute patches for updating a software package.
3117 * Tips for Patch Producers:: Advice for making patches.
3118 * Tips for Patch Consumers:: Advice for using patches.
3119 * Avoiding Common Mistakes:: Avoiding common mistakes when using `patch'.
3120 * Generating Smaller Patches:: How to generate smaller patches.
3123 File: diff.info, Node: Tips for Patch Producers, Next: Tips for Patch Consumers, Up: Making Patches
3125 Tips for Patch Producers
3126 ========================
3128 To create a patch that changes an older version of a package into a
3129 newer version, first make a copy of the older and newer versions in
3130 adjacent subdirectories. It is common to do that by unpacking `tar'
3131 archives of the two versions.
3133 To generate the patch, use the command `diff -Naur OLD NEW' where
3134 OLD and NEW identify the old and new directories. The names OLD and
3135 NEW should not contain any slashes. The `-N' option lets the patch
3136 create and remove files; `-a' lets the patch update non-text files; `-u'
3137 generates useful time stamps and enough context; and `-r' lets the
3138 patch update subdirectories. Here is an example command, using Bourne
3141 diff -Naur gcc-3.0.3 gcc-3.0.4
3143 Tell your recipients how to apply the patches. This should include
3144 which working directory to use, and which `patch' options to use; the
3145 option `-p1' is recommended. Test your procedure by pretending to be a
3146 recipient and applying your patches to a copy of the original files.
3148 *Note Avoiding Common Mistakes::, for how to avoid common mistakes
3149 when generating a patch.
3152 File: diff.info, Node: Tips for Patch Consumers, Next: Avoiding Common Mistakes, Prev: Tips for Patch Producers, Up: Making Patches
3154 Tips for Patch Consumers
3155 ========================
3157 A patch producer should tell recipients how to apply the patches, so
3158 the first rule of thumb for a patch consumer is to follow the
3159 instructions supplied with the patch.
3161 GNU `diff' can analyze files with arbitrarily long lines and files
3162 that end in incomplete lines. However, older versions of `patch'
3163 cannot patch such files. If you are having trouble applying such
3164 patches, try upgrading to a recent version of GNU `patch'.
3167 File: diff.info, Node: Avoiding Common Mistakes, Next: Generating Smaller Patches, Prev: Tips for Patch Consumers, Up: Making Patches
3169 Avoiding Common Mistakes
3170 ========================
3172 When producing a patch for multiple files, apply `diff' to
3173 directories whose names do not have slashes. This reduces confusion
3174 when the patch consumer specifies the `-pNUMBER' option, since this
3175 option can have surprising results when the old and new file names have
3176 different numbers of slashes. For example, do not send a patch with a
3177 header that looks like this:
3179 diff -Naur v2.0.29/prog/README prog/README
3180 --- v2.0.29/prog/README 2002-03-10 23:30:39.942229878 -0800
3181 +++ prog/README 2002-03-17 20:49:32.442260588 -0800
3183 because the two file names have different numbers of slashes, and
3184 different versions of `patch' interpret the file names differently. To
3185 avoid confusion, send output that looks like this instead:
3187 diff -Naur v2.0.29/prog/README v2.0.30/prog/README
3188 --- v2.0.29/prog/README 2002-03-10 23:30:39.942229878 -0800
3189 +++ v2.0.30/prog/README 2002-03-17 20:49:32.442260588 -0800
3191 Make sure you have specified the file names correctly, either in a
3192 context diff header or with an `Index:' line. Take care to not send out
3193 reversed patches, since these make people wonder whether they have
3194 already applied the patch.
3196 Avoid sending patches that compare backup file names like
3197 `README.orig' or `README~', since this might confuse `patch' into
3198 patching a backup file instead of the real file. Instead, send patches
3199 that compare the same base file names in different directories, e.g.
3200 `old/README' and `new/README'.
3202 To save people from partially applying a patch before other patches
3203 that should have gone before it, you can make the first patch in the
3204 patch file update a file with a name like `patchlevel.h' or
3205 `version.c', which contains a patch level or version number. If the
3206 input file contains the wrong version number, `patch' will complain
3209 An even clearer way to prevent this problem is to put a `Prereq:'
3210 line before the patch. If the leading text in the patch file contains a
3211 line that starts with `Prereq:', `patch' takes the next word from that
3212 line (normally a version number) and checks whether the next input file
3213 contains that word, preceded and followed by either white space or a
3214 newline. If not, `patch' prompts you for confirmation before
3215 proceeding. This makes it difficult to accidentally apply patches in
3219 File: diff.info, Node: Generating Smaller Patches, Prev: Avoiding Common Mistakes, Up: Making Patches
3221 Generating Smaller Patches
3222 ==========================
3224 The simplest way to generate a patch is to use `diff -Naur' (*note
3225 Tips for Patch Producers::), but you might be able to reduce the size
3226 of the patch by renaming or removing some files before making the
3227 patch. If the older version of the package contains any files that the
3228 newer version does not, or if any files have been renamed between the
3229 two versions, make a list of `rm' and `mv' commands for the user to
3230 execute in the old version directory before applying the patch. Then
3231 run those commands yourself in the scratch directory.
3233 If there are any files that you don't need to include in the patch
3234 because they can easily be rebuilt from other files (for example,
3235 `TAGS' and output from `yacc' and `makeinfo'), exclude them from the
3236 patch by giving `diff' the `-x PATTERN' option (*note Comparing
3237 Directories::). If you want your patch to modify a derived file
3238 because your recipients lack tools to build it, make sure that the
3239 patch for the derived file follows any patches for files that it
3240 depends on, so that the recipients' time stamps will not confuse `make'.
3242 Now you can create the patch using `diff -Naur'. Make sure to
3243 specify the scratch directory first and the newer directory second.
3245 Add to the top of the patch a note telling the user any `rm' and
3246 `mv' commands to run before applying the patch. Then you can remove
3247 the scratch directory.
3249 You can also shrink the patch size by using fewer lines of context,
3250 but bear in mind that `patch' typically needs at least two lines for
3251 proper operation when patches do not exactly match the input files.
3254 File: diff.info, Node: Invoking cmp, Next: Invoking diff, Prev: Making Patches, Up: Top
3259 The `cmp' command compares two files, and if they differ, tells the
3260 first byte and line number where they differ. Bytes and lines are
3261 numbered starting with 1. The arguments of `cmp' are as follows:
3263 cmp OPTIONS... FROM-FILE [TO-FILE [FROM-SKIP [TO-SKIP]]]
3265 The file name `-' is always the standard input. `cmp' also uses the
3266 standard input if one file name is omitted. The FROM-SKIP and TO-SKIP
3267 operands specify how many bytes to ignore at the start of each file;
3268 they are equivalent to the `--ignore-initial=FROM-SKIP:TO-SKIP' option.
3270 An exit status of 0 means no differences were found, 1 means some
3271 differences were found, and 2 means trouble.
3275 * cmp Options:: Summary of options to `cmp'.
3278 File: diff.info, Node: cmp Options, Up: Invoking cmp
3283 Below is a summary of all of the options that GNU `cmp' accepts.
3284 Most options have two equivalent names, one of which is a single letter
3285 preceded by `-', and the other of which is a long name preceded by
3286 `--'. Multiple single letter options (unless they take an argument)
3287 can be combined into a single command line word: `-bl' is equivalent to
3292 Print the differing bytes. Display control bytes as a `^'
3293 followed by a letter of the alphabet and precede bytes that have
3294 the high bit set with `M-' (which stands for "meta").
3297 Output a summary of usage and then exit.
3300 `--ignore-initial=SKIP'
3301 Ignore any differences in the first SKIP bytes of the input files.
3302 Treat files with fewer than SKIP bytes as if they are empty. If
3303 SKIP is of the form `FROM-SKIP:TO-SKIP', skip the first FROM-SKIP
3304 bytes of the first input file and the first TO-SKIP bytes of the
3309 Print the (decimal) byte numbers and (octal) values of all
3314 Compare at most COUNT input bytes.
3319 Do not print anything; only return an exit status indicating
3320 whether the files differ.
3324 Output version information and then exit.
3326 In the above table, operands that are byte counts are normally
3327 decimal, but may be preceded by `0' for octal and `0x' for hexadecimal.
3329 A byte count can be followed by a suffix to specify a multiple of
3330 that count; in this case an omitted integer is understood to be 1. A
3331 bare size letter, or one followed by `iB', specifies a multiple using
3332 powers of 1024. A size letter followed by `B' specifies powers of 1000
3333 instead. For example, `-n 4M' and `-n 4MiB' are equivalent to `-n
3334 4194304', whereas `-n 4MB' is equivalent to `-n 4000000'. This
3335 notation is upward compatible with the SI prefixes
3336 (http://www.bipm.fr/enus/3_SI/si-prefixes.html) for decimal multiples
3337 and with the IEC 60027-2 prefixes for binary multiples
3338 (http://physics.nist.gov/cuu/Units/binary.html).
3340 The following suffixes are defined. Large sizes like `1Y' may be
3341 rejected by your computer due to limitations of its arithmetic.
3344 kilobyte: 10^3 = 1000.
3349 kibibyte: 2^10 = 1024. `K' is special: the SI prefix is `k' and
3350 the IEC 60027-2 prefix is `Ki', but tradition and POSIX use `k' to
3354 megabyte: 10^6 = 1,000,000.
3358 mebibyte: 2^20 = 1,048,576.
3361 gigabyte: 10^9 = 1,000,000,000.
3365 gibibyte: 2^30 = 1,073,741,824.
3368 terabyte: 10^12 = 1,000,000,000,000.
3372 tebibyte: 2^40 = 1,099,511,627,776.
3375 petabyte: 10^15 = 1,000,000,000,000,000.
3379 pebibyte: 2^50 = 1,125,899,906,842,624.
3382 exabyte: 10^18 = 1,000,000,000,000,000,000.
3386 exbibyte: 2^60 = 1,152,921,504,606,846,976.
3389 zettabyte: 10^21 = 1,000,000,000,000,000,000,000
3393 2^70 = 1,180,591,620,717,411,303,424. (`Zi' is a GNU extension to
3397 yottabyte: 10^24 = 1,000,000,000,000,000,000,000,000.
3401 2^80 = 1,208,925,819,614,629,174,706,176. (`Yi' is a GNU
3402 extension to IEC 60027-2.)
3405 File: diff.info, Node: Invoking diff, Next: Invoking diff3, Prev: Invoking cmp, Up: Top
3410 The format for running the `diff' command is:
3412 diff OPTIONS... FILES...
3414 In the simplest case, two file names FROM-FILE and TO-FILE are
3415 given, and `diff' compares the contents of FROM-FILE and TO-FILE. A
3416 file name of `-' stands for text read from the standard input. As a
3417 special case, `diff - -' compares a copy of standard input to itself.
3419 If one file is a directory and the other is not, `diff' compares the
3420 file in the directory whose name is that of the non-directory. The
3421 non-directory file must not be `-'.
3423 If two file names are given and both are directories, `diff'
3424 compares corresponding files in both directories, in alphabetical
3425 order; this comparison is not recursive unless the `-r' or
3426 `--recursive' option is given. `diff' never compares the actual
3427 contents of a directory as if it were a file. The file that is fully
3428 specified may not be standard input, because standard input is nameless
3429 and the notion of "file with the same name" does not apply.
3431 If the `--from-file=FILE' option is given, the number of file names
3432 is arbitrary, and FILE is compared to each named file. Similarly, if
3433 the `--to-file=FILE' option is given, each named file is compared to
3436 `diff' options begin with `-', so normally file names may not begin
3437 with `-'. However, `--' as an argument by itself treats the remaining
3438 arguments as file names even if they begin with `-'.
3440 An exit status of 0 means no differences were found, 1 means some
3441 differences were found, and 2 means trouble.
3445 * diff Options:: Summary of options to `diff'.
3448 File: diff.info, Node: diff Options, Up: Invoking diff
3453 Below is a summary of all of the options that GNU `diff' accepts.
3454 Most options have two equivalent names, one of which is a single letter
3455 preceded by `-', and the other of which is a long name preceded by
3456 `--'. Multiple single letter options (unless they take an argument)
3457 can be combined into a single command line word: `-ac' is equivalent to
3458 `-a -c'. Long named options can be abbreviated to any unique prefix of
3459 their name. Brackets ([ and ]) indicate that an option takes an
3464 Treat all files as text and compare them line-by-line, even if they
3465 do not seem to be text. *Note Binary::.
3468 `--ignore-space-change'
3469 Ignore changes in amount of white space. *Note White Space::.
3472 `--ignore-blank-lines'
3473 Ignore changes that just insert or delete blank lines. *Note
3477 Read and write data in binary mode. *Note Binary::.
3480 Use the context output format, showing three lines of context.
3481 *Note Context Format::.
3485 Use the context output format, showing LINES (an integer) lines of
3486 context, or three if LINES is not given. *Note Context Format::.
3487 For proper operation, `patch' typically needs at least two lines of
3490 On older systems, `diff' supports an obsolete option `-LINES' that
3491 has effect when combined with `-c' or `-p'. POSIX 1003.1-2001
3492 (*note Standards conformance::) does not allow this; use `-C LINES'
3495 `--changed-group-format=FORMAT'
3496 Use FORMAT to output a line group containing differing lines from
3497 both files in if-then-else format. *Note Line Group Formats::.
3501 Change the algorithm perhaps find a smaller set of changes. This
3502 makes `diff' slower (sometimes much slower). *Note diff
3507 Make merged `#ifdef' format output, conditional on the preprocessor
3508 macro NAME. *Note If-then-else::.
3512 Make output that is a valid `ed' script. *Note ed Scripts::.
3515 `--ignore-tab-expansion'
3516 Ignore changes due to tab expansion. *Note White Space::.
3520 Make output that looks vaguely like an `ed' script but has changes
3521 in the order they appear in the file. *Note Forward ed::.
3524 `--show-function-line=REGEXP'
3525 In context and unified format, for each hunk of differences, show
3526 some of the last preceding line that matches REGEXP. *Note
3527 Specified Headings::.
3530 Compare FILE to each operand; FILE may be a directory.
3533 Output a summary of usage and then exit.
3535 `--horizon-lines=LINES'
3536 Do not discard the last LINES lines of the common prefix and the
3537 first LINES lines of the common suffix. *Note diff Performance::.
3541 Ignore changes in case; consider upper- and lower-case letters
3542 equivalent. *Note Case Folding::.
3545 `--ignore-matching-lines=REGEXP'
3546 Ignore changes that just insert or delete lines that match REGEXP.
3547 *Note Specified Folding::.
3549 `--ignore-file-name-case'
3550 Ignore case when comparing file names during recursive comparison.
3551 *Note Comparing Directories::.
3555 Pass the output through `pr' to paginate it. *Note Pagination::.
3558 Use LABEL instead of the file name in the context format (*note
3559 Context Format::) and unified format (*note Unified Format::)
3560 headers. *Note RCS::.
3563 Print only the left column of two common lines in side by side
3564 format. *Note Side by Side Format::.
3566 `--line-format=FORMAT'
3567 Use FORMAT to output all input lines in if-then-else format.
3568 *Note Line Formats::.
3572 Output RCS-format diffs; like `-f' except that each command
3573 specifies the number of lines affected. *Note RCS::.
3577 In directory comparison, if a file is found in only one directory,
3578 treat it as present but empty in the other directory. *Note
3579 Comparing Directories::.
3581 `--new-group-format=FORMAT'
3582 Use FORMAT to output a group of lines taken from just the second
3583 file in if-then-else format. *Note Line Group Formats::.
3585 `--new-line-format=FORMAT'
3586 Use FORMAT to output a line taken from just the second file in
3587 if-then-else format. *Note Line Formats::.
3589 `--old-group-format=FORMAT'
3590 Use FORMAT to output a group of lines taken from just the first
3591 file in if-then-else format. *Note Line Group Formats::.
3593 `--old-line-format=FORMAT'
3594 Use FORMAT to output a line taken from just the first file in
3595 if-then-else format. *Note Line Formats::.
3599 Show which C function each change is in. *Note C Function
3604 Report only whether the files differ, not the details of the
3605 differences. *Note Brief::.
3609 When comparing directories, recursively compare any subdirectories
3610 found. *Note Comparing Directories::.
3613 `--report-identical-files'
3614 Report when two files are the same. *Note Comparing Directories::.
3617 `--starting-file=FILE'
3618 When comparing directories, start with the file FILE. This is
3619 used for resuming an aborted comparison. *Note Comparing
3622 `--speed-large-files'
3623 Use heuristics to speed handling of large files that have numerous
3624 scattered small changes. *Note diff Performance::.
3626 `--strip-trailing-cr'
3627 Strip any trailing carriage return at the end of an input line.
3630 `--suppress-common-lines'
3631 Do not print common lines in side by side format. *Note Side by
3636 Expand tabs to spaces in the output, to preserve the alignment of
3637 tabs in the input files. *Note Tabs::.
3641 Output a tab rather than a space before the text of a line in
3642 normal or context format. This causes the alignment of tabs in
3643 the line to look normal. *Note Tabs::.
3646 Compare each operand to FILE; FILE may be a directory.
3649 Use the unified output format, showing three lines of context.
3650 *Note Unified Format::.
3652 `--unchanged-group-format=FORMAT'
3653 Use FORMAT to output a group of common lines taken from both files
3654 in if-then-else format. *Note Line Group Formats::.
3656 `--unchanged-line-format=FORMAT'
3657 Use FORMAT to output a line common to both files in if-then-else
3658 format. *Note Line Formats::.
3660 `--unidirectional-new-file'
3661 When comparing directories, if a file appears only in the second
3662 directory of the two, treat it as present but empty in the other.
3663 *Note Comparing Directories::.
3667 Use the unified output format, showing LINES (an integer) lines of
3668 context, or three if LINES is not given. *Note Unified Format::.
3669 For proper operation, `patch' typically needs at least two lines of
3672 On older systems, `diff' supports an obsolete option `-LINES' that
3673 has effect when combined with `-u'. POSIX 1003.1-2001 (*note
3674 Standards conformance::) does not allow this; use `-U LINES'
3679 Output version information and then exit.
3682 `--ignore-all-space'
3683 Ignore white space when comparing lines. *Note White Space::.
3687 Output at most COLUMNS (default 130) print columns per line in
3688 side by side format. *Note Side by Side Format::.
3692 When comparing directories, ignore files and subdirectories whose
3693 basenames match PATTERN. *Note Comparing Directories::.
3696 `--exclude-from=FILE'
3697 When comparing directories, ignore files and subdirectories whose
3698 basenames match any pattern contained in FILE. *Note Comparing
3703 Use the side by side output format. *Note Side by Side Format::.
3706 File: diff.info, Node: Invoking diff3, Next: Invoking patch, Prev: Invoking diff, Up: Top
3711 The `diff3' command compares three files and outputs descriptions of
3712 their differences. Its arguments are as follows:
3714 diff3 OPTIONS... MINE OLDER YOURS
3716 The files to compare are MINE, OLDER, and YOURS. At most one of
3717 these three file names may be `-', which tells `diff3' to read the
3718 standard input for that file.
3720 An exit status of 0 means `diff3' was successful, 1 means some
3721 conflicts were found, and 2 means trouble.
3725 * diff3 Options:: Summary of options to `diff3'.
3728 File: diff.info, Node: diff3 Options, Up: Invoking diff3
3733 Below is a summary of all of the options that GNU `diff3' accepts.
3734 Multiple single letter options (unless they take an argument) can be
3735 combined into a single command line argument.
3739 Treat all files as text and compare them line-by-line, even if they
3740 do not appear to be text. *Note Binary::.
3744 Incorporate all unmerged changes from OLDER to YOURS into MINE,
3745 surrounding conflicts with bracket lines. *Note Marking
3748 `--diff-program=PROGRAM'
3749 Use the compatible comparison program PROGRAM to compare files
3754 Generate an `ed' script that incorporates all the changes from
3755 OLDER to YOURS into MINE. *Note Which Changes::.
3759 Like `-e', except bracket lines from overlapping changes' first
3760 and third files. *Note Marking Conflicts::. With `-E', an
3761 overlapping change looks like this:
3770 Output a summary of usage and then exit.
3773 Generate `w' and `q' commands at the end of the `ed' script for
3774 System V compatibility. This option must be combined with one of
3775 the `-AeExX3' options, and may not be combined with `-m'. *Note
3776 Saving the Changed File::.
3780 Use the label LABEL for the brackets output by the `-A', `-E' and
3781 `-X' options. This option may be given up to three times, one for
3782 each input file. The default labels are the names of the input
3783 files. Thus `diff3 -L X -L Y -L Z -m A B C' acts like `diff3 -m A
3784 B C', except that the output looks like it came from files named
3785 `X', `Y' and `Z' rather than from files named `A', `B' and `C'.
3786 *Note Marking Conflicts::.
3790 Apply the edit script to the first file and send the result to
3791 standard output. Unlike piping the output from `diff3' to `ed',
3792 this works even for binary files and incomplete lines. `-A' is
3793 assumed if no edit script option is specified. *Note Bypassing
3798 Output a tab rather than two spaces before the text of a line in
3799 normal format. This causes the alignment of tabs in the line to
3800 look normal. *Note Tabs::.
3804 Output version information and then exit.
3808 Like `-e', except output only the overlapping changes. *Note
3812 Like `-E', except output only the overlapping changes. In other
3813 words, like `-x', except bracket changes as in `-E'. *Note
3814 Marking Conflicts::.
3818 Like `-e', except output only the nonoverlapping changes. *Note
3822 File: diff.info, Node: Invoking patch, Next: Invoking sdiff, Prev: Invoking diff3, Up: Top
3827 Normally `patch' is invoked like this:
3831 The full format for invoking `patch' is:
3833 patch OPTIONS... [ORIGFILE [PATCHFILE]]
3835 You can also specify where to read the patch from with the `-i
3836 PATCHFILE' or `--input=PATCHFILE' option. If you do not specify
3837 PATCHFILE, or if PATCHFILE is `-', `patch' reads the patch (that is,
3838 the `diff' output) from the standard input.
3840 If you do not specify an input file on the command line, `patch'
3841 tries to intuit from the "leading text" (any text in the patch that
3842 comes before the `diff' output) which file to edit. *Note Multiple
3845 By default, `patch' replaces the original input file with the
3846 patched version, possibly after renaming the original file into a
3847 backup file (*note Backup Names::, for a description of how `patch'
3848 names backup files). You can also specify where to put the output with
3849 the `-o FILE' or `--output=FILE' option; however, do not use this option
3850 if FILE is one of the input files.
3854 * patch Options:: Summary table of options to `patch'.
3857 File: diff.info, Node: patch Options, Up: Invoking patch
3862 Here is a summary of all of the options that GNU `patch' accepts.
3863 *Note patch and Tradition::, for which of these options are safe to use
3864 in older versions of `patch'.
3866 Multiple single-letter options that do not take an argument can be
3867 combined into a single command line argument with only one dash.
3871 Back up the original contents of each file, even if backups would
3872 normally not be made. *Note Backups::.
3876 Prepend PREFIX to backup file names. *Note Backup Names::.
3878 `--backup-if-mismatch'
3879 Back up the original contents of each file if the patch does not
3880 exactly match the file. This is the default behavior when not
3881 conforming to POSIX. *Note Backups::.
3884 Read and write all files in binary mode, except for standard output
3885 and `/dev/tty'. This option has no effect on POSIX-conforming
3886 systems like GNU/Linux. On systems where this option makes a
3887 difference, the patch should be generated by `diff -a --binary'.
3892 Interpret the patch file as a context diff. *Note patch Input::.
3895 `--directory=DIRECTORY'
3896 Make directory DIRECTORY the current directory for interpreting
3897 both file names in the patch file, and file names given as
3898 arguments to other options. *Note patch Directories::.
3902 Make merged if-then-else output using NAME. *Note If-then-else::.
3905 Print the results of applying the patches without actually changing
3906 any files. *Note Dry Runs::.
3910 Interpret the patch file as an `ed' script. *Note patch Input::.
3913 `--remove-empty-files'
3914 Remove output files that are empty after the patches have been
3915 applied. *Note Creating and Removing::.
3919 Assume that the user knows exactly what he or she is doing, and do
3920 not ask any questions. *Note patch Messages::.
3924 Set the maximum fuzz factor to LINES. *Note Inexact::.
3928 If NUM is positive, get input files from a revision control system
3929 as necessary; if zero, do not get the files; if negative, ask the
3930 user whether to get the files. *Note Revision Control::.
3933 Output a summary of usage and then exit.
3937 Read the patch from PATCHFILE rather than from standard input.
3938 *Note patch Options::.
3941 `--ignore-white-space'
3942 Let any sequence of blanks (spaces or tabs) in the patch file match
3943 any sequence of blanks in the input file. *Note Changed White
3948 Interpret the patch file as a normal diff. *Note patch Input::.
3952 Ignore patches that `patch' thinks are reversed or already applied.
3953 See also `-R'. *Note Reversed Patches::.
3955 `--no-backup-if-mismatch'
3956 Do not back up the original contents of files. This is the default
3957 behavior when conforming to POSIX. *Note Backups::.
3961 Use FILE as the output file name. *Note patch Options::.
3965 Set the file name strip count to NUMBER. *Note patch
3969 Conform to POSIX, as if the `POSIXLY_CORRECT' environment variable
3970 had been set. *Note patch and POSIX::.
3972 `--quoting-style=WORD'
3973 Use style WORD to quote names in diagnostics, as if the
3974 `QUOTING_STYLE' environment variable had been set to WORD. *Note
3975 patch Quoting Style::.
3978 `--reject-file=REJECT-FILE'
3979 Use REJECT-FILE as the reject file name. *Note Reject Names::.
3983 Assume that this patch was created with the old and new files
3984 swapped. *Note Reversed Patches::.
3989 Work silently unless an error occurs. *Note patch Messages::.
3993 Do not ask any questions. *Note patch Messages::.
3997 Set the modification and access times of patched files from time
3998 stamps given in context diff headers, assuming that the context
3999 diff headers use local time. *Note Patching Time Stamps::.
4003 Interpret the patch file as a unified diff. *Note patch Input::.
4007 Output version information and then exit.
4010 `--version=control=BACKUP-STYLE'
4011 Select the naming convention for backup file names. *Note Backup
4015 Print more diagnostics than usual. *Note patch Messages::.
4019 Set internal debugging flags. Of interest only to `patch'
4023 `--basename-prefix=PREFIX'
4024 Prepend PREFIX to base names of backup files. *Note Backup
4029 Use SUFFIX as the backup extension instead of `.orig' or `~'.
4030 *Note Backup Names::.
4034 Set the modification and access times of patched files from time
4035 stamps given in context diff headers, assuming that the context
4036 diff headers use UTC. *Note Patching Time Stamps::.
4039 File: diff.info, Node: Invoking sdiff, Next: Standards conformance, Prev: Invoking patch, Up: Top
4044 The `sdiff' command merges two files and interactively outputs the
4045 results. Its arguments are as follows:
4047 sdiff -o OUTFILE OPTIONS... FROM-FILE TO-FILE
4049 This merges FROM-FILE with TO-FILE, with output to OUTFILE. If
4050 FROM-FILE is a directory and TO-FILE is not, `sdiff' compares the file
4051 in FROM-FILE whose file name is that of TO-FILE, and vice versa.
4052 FROM-FILE and TO-FILE may not both be directories.
4054 `sdiff' options begin with `-', so normally FROM-FILE and TO-FILE
4055 may not begin with `-'. However, `--' as an argument by itself treats
4056 the remaining arguments as file names even if they begin with `-'. You
4057 may not use `-' as an input file.
4059 `sdiff' without `-o' (or `--output') produces a side-by-side
4060 difference. This usage is obsolete; use the `-y' or `--side-by-side'
4061 option of `diff' instead.
4063 An exit status of 0 means no differences were found, 1 means some
4064 differences were found, and 2 means trouble.
4068 * sdiff Options:: Summary of options to `diff'.
4071 File: diff.info, Node: sdiff Options, Up: Invoking sdiff
4076 Below is a summary of all of the options that GNU `sdiff' accepts.
4077 Each option has two equivalent names, one of which is a single letter
4078 preceded by `-', and the other of which is a long name preceded by
4079 `--'. Multiple single letter options (unless they take an argument)
4080 can be combined into a single command line argument. Long named
4081 options can be abbreviated to any unique prefix of their name.
4085 Treat all files as text and compare them line-by-line, even if they
4086 do not appear to be text. *Note Binary::.
4089 `--ignore-space-change'
4090 Ignore changes in amount of white space. *Note White Space::.
4093 `--ignore-blank-lines'
4094 Ignore changes that just insert or delete blank lines. *Note
4099 Change the algorithm to perhaps find a smaller set of changes.
4100 This makes `sdiff' slower (sometimes much slower). *Note diff
4103 `--diff-program=PROGRAM'
4104 Use the compatible comparison program PROGRAM to compare files
4108 `--ignore-tab-expansion'
4109 Ignore changes due to tab expansion. *Note White Space::.
4112 Output a summary of usage and then exit.
4116 Ignore changes in case; consider upper- and lower-case to be the
4117 same. *Note Case Folding::.
4120 `--ignore-matching-lines=REGEXP'
4121 Ignore changes that just insert or delete lines that match REGEXP.
4122 *Note Specified Folding::.
4126 Print only the left column of two common lines. *Note Side by
4131 Put merged output into FILE. This option is required for merging.
4134 `--suppress-common-lines'
4135 Do not print common lines. *Note Side by Side Format::.
4137 `--speed-large-files'
4138 Use heuristics to speed handling of large files that have numerous
4139 scattered small changes. *Note diff Performance::.
4141 `--strip-trailing-cr'
4142 Strip any trailing carriage return at the end of an input line.
4147 Expand tabs to spaces in the output, to preserve the alignment of
4148 tabs in the input files. *Note Tabs::.
4152 Output version information and then exit.
4156 Output at most COLUMNS (default 130) print columns per line.
4157 *Note Side by Side Format::. Note that for historical reasons,
4158 this option is `-W' in `diff', `-w' in `sdiff'.
4161 `--ignore-all-space'
4162 Ignore white space when comparing lines. *Note White Space::.
4163 Note that for historical reasons, this option is `-w' in `diff',
4167 File: diff.info, Node: Standards conformance, Next: Projects, Prev: Invoking sdiff, Up: Top
4169 Standards conformance
4170 *********************
4172 In a few cases, the GNU utilities' default behavior is incompatible
4173 with the POSIX standard. To suppress these incompatibilities, define
4174 the `POSIXLY_CORRECT' environment variable. Unless you are checking
4175 for POSIX conformance, you probably do not need to define
4178 Normally options and operands can appear in any order, and programs
4179 act as if all the options appear before any operands. For example,
4180 `diff lao tzu -C 2' acts like `diff -C 2 lao tzu', since `2' is an
4181 option-argument of `-C'. However, if the `POSIXLY_CORRECT' environment
4182 variable is set, options must appear before operands, unless otherwise
4183 specified for a particular command.
4185 Newer versions of POSIX are occasionally incompatible with older
4186 versions. For example, older versions of POSIX allowed the command
4187 `diff -c -10' to have the same meaning as `diff -C 10', but POSIX
4188 1003.1-2001 `diff' no longer allows digit-string options like `-10'.
4190 The GNU utilities normally conform to the version of POSIX that is
4191 standard for your system. To cause them to conform to a different
4192 version of POSIX, define the `_POSIX2_VERSION' environment variable to
4193 a value of the form YYYYMM specifying the year and month the standard
4194 was adopted. Two values are currently supported for `_POSIX2_VERSION':
4195 `199209' stands for POSIX 1003.2-1992, and `200112' stands for POSIX
4196 1003.1-2001. For example, if you are running older software that
4197 assumes an older version of POSIX and uses `diff -c -10', you can work
4198 around the compatibility problems by setting `_POSIX2_VERSION=199209'
4199 in your environment.
4202 File: diff.info, Node: Projects, Next: Copying This Manual, Prev: Standards conformance, Up: Top
4207 Here are some ideas for improving GNU `diff' and `patch'. The GNU
4208 project has identified some improvements as potential programming
4209 projects for volunteers. You can also help by reporting any bugs that
4212 If you are a programmer and would like to contribute something to the
4213 GNU project, please consider volunteering for one of these projects.
4214 If you are seriously contemplating work, please write to <gnu@gnu.org>
4215 to coordinate with other volunteers.
4219 * Shortcomings:: Suggested projects for improvements.
4220 * Bugs:: Reporting bugs.
4223 File: diff.info, Node: Shortcomings, Next: Bugs, Up: Projects
4225 Suggested Projects for Improving GNU `diff' and `patch'
4226 =======================================================
4228 One should be able to use GNU `diff' to generate a patch from any
4229 pair of directory trees, and given the patch and a copy of one such
4230 tree, use `patch' to generate a faithful copy of the other.
4231 Unfortunately, some changes to directory trees cannot be expressed using
4232 current patch formats; also, `patch' does not handle some of the
4233 existing formats. These shortcomings motivate the following suggested
4238 * Internationalization:: Handling multibyte and varying-width characters.
4239 * Changing Structure:: Handling changes to the directory structure.
4240 * Special Files:: Handling symbolic links, device special files, etc.
4241 * Unusual File Names:: Handling file names that contain unusual characters.
4242 * Time Stamp Order:: Outputting diffs in time stamp order.
4243 * Ignoring Changes:: Ignoring certain changes while showing others.
4244 * Speedups:: Improving performance.
4247 File: diff.info, Node: Internationalization, Next: Changing Structure, Up: Shortcomings
4249 Handling Multibyte and Varying-Width Characters
4250 -----------------------------------------------
4252 `diff', `diff3' and `sdiff' treat each line of input as a string of
4253 unibyte characters. This can mishandle multibyte characters in some
4254 cases. For example, when asked to ignore spaces, `diff' does not
4255 properly ignore a multibyte space character.
4257 Also, `diff' currently assumes that each byte is one column wide,
4258 and this assumption is incorrect in some locales, e.g., locales that
4259 use UTF-8 encoding. This causes problems with the `-y' or
4260 `--side-by-side' option of `diff'.
4262 These problems need to be fixed without unduly affecting the
4263 performance of the utilities in unibyte environments.
4265 The IBM GNU/Linux Technology Center Internationalization Team has
4266 proposed some patches to support internationalized `diff'
4267 `http://oss.software.ibm.com/developer/opensource/linux/patches/i18n/diffutils-2.7.2-i18n-0.1.patch.gz'.
4268 Unfortunately, these patches are incomplete and are to an older version
4269 of `diff', so more work needs to be done in this area.
4272 File: diff.info, Node: Changing Structure, Next: Special Files, Prev: Internationalization, Up: Shortcomings
4274 Handling Changes to the Directory Structure
4275 -------------------------------------------
4277 `diff' and `patch' do not handle some changes to directory
4278 structure. For example, suppose one directory tree contains a directory
4279 named `D' with some subsidiary files, and another contains a file with
4280 the same name `D'. `diff -r' does not output enough information for
4281 `patch' to transform the directory subtree into the file.
4283 There should be a way to specify that a file has been removed without
4284 having to include its entire contents in the patch file. There should
4285 also be a way to tell `patch' that a file was renamed, even if there is
4286 no way for `diff' to generate such information. There should be a way
4287 to tell `patch' that a file's time stamp has changed, even if its
4288 contents have not changed.
4290 These problems can be fixed by extending the `diff' output format to
4291 represent changes in directory structure, and extending `patch' to
4292 understand these extensions.
4295 File: diff.info, Node: Special Files, Next: Unusual File Names, Prev: Changing Structure, Up: Shortcomings
4297 Files that are Neither Directories Nor Regular Files
4298 ----------------------------------------------------
4300 Some files are neither directories nor regular files: they are
4301 unusual files like symbolic links, device special files, named pipes,
4302 and sockets. Currently, `diff' treats symbolic links like regular
4303 files; it treats other special files like regular files if they are
4304 specified at the top level, but simply reports their presence when
4305 comparing directories. This means that `patch' cannot represent changes
4306 to such files. For example, if you change which file a symbolic link
4307 points to, `diff' outputs the difference between the two files, instead
4308 of the change to the symbolic link.
4310 `diff' should optionally report changes to special files specially,
4311 and `patch' should be extended to understand these extensions.
4314 File: diff.info, Node: Unusual File Names, Next: Time Stamp Order, Prev: Special Files, Up: Shortcomings
4316 File Names that Contain Unusual Characters
4317 ------------------------------------------
4319 When a file name contains an unusual character like a newline or
4320 white space, `diff -r' generates a patch that `patch' cannot parse.
4321 The problem is with format of `diff' output, not just with `patch',
4322 because with odd enough file names one can cause `diff' to generate a
4323 patch that is syntactically correct but patches the wrong files. The
4324 format of `diff' output should be extended to handle all possible file
4328 File: diff.info, Node: Time Stamp Order, Next: Ignoring Changes, Prev: Unusual File Names, Up: Shortcomings
4330 Outputting Diffs in Time Stamp Order
4331 ------------------------------------
4333 Applying `patch' to a multiple-file diff can result in files whose
4334 time stamps are out of order. GNU `patch' has options to restore the
4335 time stamps of the updated files (*note Patching Time Stamps::), but
4336 sometimes it is useful to generate a patch that works even if the
4337 recipient does not have GNU patch, or does not use these options. One
4338 way to do this would be to implement a `diff' option to output diffs in
4342 File: diff.info, Node: Ignoring Changes, Next: Speedups, Prev: Time Stamp Order, Up: Shortcomings
4344 Ignoring Certain Changes
4345 ------------------------
4347 It would be nice to have a feature for specifying two strings, one in
4348 FROM-FILE and one in TO-FILE, which should be considered to match.
4349 Thus, if the two strings are `foo' and `bar', then if two lines differ
4350 only in that `foo' in file 1 corresponds to `bar' in file 2, the lines
4351 are treated as identical.
4353 It is not clear how general this feature can or should be, or what
4354 syntax should be used for it.
4356 A partial substitute is to filter one or both files before comparing,
4359 sed 's/foo/bar/g' file1 | diff - file2
4361 However, this outputs the filtered text, not the original.
4364 File: diff.info, Node: Speedups, Prev: Ignoring Changes, Up: Shortcomings
4366 Improving Performance
4367 ---------------------
4369 When comparing two large directory structures, one of which was
4370 originally copied from the other with time stamps preserved (e.g., with
4371 `cp -pR'), it would greatly improve performance if an option told
4372 `diff' to assume that two files with the same size and time stamps have
4373 the same content. *Note diff Performance::.
4376 File: diff.info, Node: Bugs, Prev: Shortcomings, Up: Projects
4381 If you think you have found a bug in GNU `cmp', `diff', `diff3', or
4382 `sdiff', please report it by electronic mail to the GNU utilities bug
4384 (http://mail.gnu.org/mailman/listinfo/bug-gnu-utils)
4385 <bug-gnu-utils@gnu.org>. Please send bug reports for GNU `patch' to
4386 <bug-patch@gnu.org>. Send as precise a description of the problem as
4387 you can, including the output of the `--version' option and sample
4388 input files that produce the bug, if applicable. If you have a
4389 nontrivial fix for the bug, please send it as well. If you have a
4390 patch, please send it too. It may simplify the maintainer's job if the
4391 patch is relative to a recent test release, which you can find in the
4392 directory `ftp://alpha.gnu.org/gnu/diffutils/'.
4395 File: diff.info, Node: Copying This Manual, Next: Index, Prev: Projects, Up: Top
4402 * GNU Free Documentation License:: License for copying this manual.
4405 File: diff.info, Node: GNU Free Documentation License, Up: Copying This Manual
4407 GNU Free Documentation License
4408 ==============================
4410 Version 1.1, March 2000
4411 Copyright (C) 2000 Free Software Foundation, Inc.
4412 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA
4414 Everyone is permitted to copy and distribute verbatim copies
4415 of this license document, but changing it is not allowed.
4419 The purpose of this License is to make a manual, textbook, or other
4420 written document "free" in the sense of freedom: to assure everyone
4421 the effective freedom to copy and redistribute it, with or without
4422 modifying it, either commercially or noncommercially. Secondarily,
4423 this License preserves for the author and publisher a way to get
4424 credit for their work, while not being considered responsible for
4425 modifications made by others.
4427 This License is a kind of "copyleft", which means that derivative
4428 works of the document must themselves be free in the same sense.
4429 It complements the GNU General Public License, which is a copyleft
4430 license designed for free software.
4432 We have designed this License in order to use it for manuals for
4433 free software, because free software needs free documentation: a
4434 free program should come with manuals providing the same freedoms
4435 that the software does. But this License is not limited to
4436 software manuals; it can be used for any textual work, regardless
4437 of subject matter or whether it is published as a printed book.
4438 We recommend this License principally for works whose purpose is
4439 instruction or reference.
4441 1. APPLICABILITY AND DEFINITIONS
4443 This License applies to any manual or other work that contains a
4444 notice placed by the copyright holder saying it can be distributed
4445 under the terms of this License. The "Document", below, refers to
4446 any such manual or work. Any member of the public is a licensee,
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4449 A "Modified Version" of the Document means any work containing the
4450 Document or a portion of it, either copied verbatim, or with
4451 modifications and/or translated into another language.
4453 A "Secondary Section" is a named appendix or a front-matter
4454 section of the Document that deals exclusively with the
4455 relationship of the publishers or authors of the Document to the
4456 Document's overall subject (or to related matters) and contains
4457 nothing that could fall directly within that overall subject.
4458 (For example, if the Document is in part a textbook of
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4460 The relationship could be a matter of historical connection with
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4464 The "Invariant Sections" are certain Secondary Sections whose
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4504 You may copy and distribute the Document in any medium, either
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4506 copyright notices, and the license notice saying this License
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4518 3. COPYING IN QUANTITY
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4589 F. Include, immediately after the copyright notices, a license
4590 notice giving the public permission to use the Modified
4591 Version under the terms of this License, in the form shown in
4594 G. Preserve in that license notice the full lists of Invariant
4595 Sections and required Cover Texts given in the Document's
4598 H. Include an unaltered copy of this License.
4600 I. Preserve the section entitled "History", and its title, and
4601 add to it an item stating at least the title, year, new
4602 authors, and publisher of the Modified Version as given on
4603 the Title Page. If there is no section entitled "History" in
4604 the Document, create one stating the title, year, authors,
4605 and publisher of the Document as given on its Title Page,
4606 then add an item describing the Modified Version as stated in
4607 the previous sentence.
4609 J. Preserve the network location, if any, given in the Document
4610 for public access to a Transparent copy of the Document, and
4611 likewise the network locations given in the Document for
4612 previous versions it was based on. These may be placed in
4613 the "History" section. You may omit a network location for a
4614 work that was published at least four years before the
4615 Document itself, or if the original publisher of the version
4616 it refers to gives permission.
4618 K. In any section entitled "Acknowledgments" or "Dedications",
4619 preserve the section's title, and preserve in the section all
4620 the substance and tone of each of the contributor
4621 acknowledgments and/or dedications given therein.
4623 L. Preserve all the Invariant Sections of the Document,
4624 unaltered in their text and in their titles. Section numbers
4625 or the equivalent are not considered part of the section
4628 M. Delete any section entitled "Endorsements". Such a section
4629 may not be included in the Modified Version.
4631 N. Do not retitle any existing section as "Endorsements" or to
4632 conflict in title with any Invariant Section.
4634 If the Modified Version includes new front-matter sections or
4635 appendices that qualify as Secondary Sections and contain no
4636 material copied from the Document, you may at your option
4637 designate some or all of these sections as invariant. To do this,
4638 add their titles to the list of Invariant Sections in the Modified
4639 Version's license notice. These titles must be distinct from any
4640 other section titles.
4642 You may add a section entitled "Endorsements", provided it contains
4643 nothing but endorsements of your Modified Version by various
4644 parties--for example, statements of peer review or that the text
4645 has been approved by an organization as the authoritative
4646 definition of a standard.
4648 You may add a passage of up to five words as a Front-Cover Text,
4649 and a passage of up to 25 words as a Back-Cover Text, to the end
4650 of the list of Cover Texts in the Modified Version. Only one
4651 passage of Front-Cover Text and one of Back-Cover Text may be
4652 added by (or through arrangements made by) any one entity. If the
4653 Document already includes a cover text for the same cover,
4654 previously added by you or by arrangement made by the same entity
4655 you are acting on behalf of, you may not add another; but you may
4656 replace the old one, on explicit permission from the previous
4657 publisher that added the old one.
4659 The author(s) and publisher(s) of the Document do not by this
4660 License give permission to use their names for publicity for or to
4661 assert or imply endorsement of any Modified Version.
4663 5. COMBINING DOCUMENTS
4665 You may combine the Document with other documents released under
4666 this License, under the terms defined in section 4 above for
4667 modified versions, provided that you include in the combination
4668 all of the Invariant Sections of all of the original documents,
4669 unmodified, and list them all as Invariant Sections of your
4670 combined work in its license notice.
4672 The combined work need only contain one copy of this License, and
4673 multiple identical Invariant Sections may be replaced with a single
4674 copy. If there are multiple Invariant Sections with the same name
4675 but different contents, make the title of each such section unique
4676 by adding at the end of it, in parentheses, the name of the
4677 original author or publisher of that section if known, or else a
4678 unique number. Make the same adjustment to the section titles in
4679 the list of Invariant Sections in the license notice of the
4682 In the combination, you must combine any sections entitled
4683 "History" in the various original documents, forming one section
4684 entitled "History"; likewise combine any sections entitled
4685 "Acknowledgments", and any sections entitled "Dedications". You
4686 must delete all sections entitled "Endorsements."
4688 6. COLLECTIONS OF DOCUMENTS
4690 You may make a collection consisting of the Document and other
4691 documents released under this License, and replace the individual
4692 copies of this License in the various documents with a single copy
4693 that is included in the collection, provided that you follow the
4694 rules of this License for verbatim copying of each of the
4695 documents in all other respects.
4697 You may extract a single document from such a collection, and
4698 distribute it individually under this License, provided you insert
4699 a copy of this License into the extracted document, and follow
4700 this License in all other respects regarding verbatim copying of
4703 7. AGGREGATION WITH INDEPENDENT WORKS
4705 A compilation of the Document or its derivatives with other
4706 separate and independent documents or works, in or on a volume of
4707 a storage or distribution medium, does not as a whole count as a
4708 Modified Version of the Document, provided no compilation
4709 copyright is claimed for the compilation. Such a compilation is
4710 called an "aggregate", and this License does not apply to the
4711 other self-contained works thus compiled with the Document, on
4712 account of their being thus compiled, if they are not themselves
4713 derivative works of the Document.
4715 If the Cover Text requirement of section 3 is applicable to these
4716 copies of the Document, then if the Document is less than one
4717 quarter of the entire aggregate, the Document's Cover Texts may be
4718 placed on covers that surround only the Document within the
4719 aggregate. Otherwise they must appear on covers around the whole
4724 Translation is considered a kind of modification, so you may
4725 distribute translations of the Document under the terms of section
4726 4. Replacing Invariant Sections with translations requires special
4727 permission from their copyright holders, but you may include
4728 translations of some or all Invariant Sections in addition to the
4729 original versions of these Invariant Sections. You may include a
4730 translation of this License provided that you also include the
4731 original English version of this License. In case of a
4732 disagreement between the translation and the original English
4733 version of this License, the original English version will prevail.
4737 You may not copy, modify, sublicense, or distribute the Document
4738 except as expressly provided for under this License. Any other
4739 attempt to copy, modify, sublicense or distribute the Document is
4740 void, and will automatically terminate your rights under this
4741 License. However, parties who have received copies, or rights,
4742 from you under this License will not have their licenses
4743 terminated so long as such parties remain in full compliance.
4745 10. FUTURE REVISIONS OF THIS LICENSE
4747 The Free Software Foundation may publish new, revised versions of
4748 the GNU Free Documentation License from time to time. Such new
4749 versions will be similar in spirit to the present version, but may
4750 differ in detail to address new problems or concerns. See
4751 `http://www.gnu.org/copyleft/'.
4753 Each version of the License is given a distinguishing version
4754 number. If the Document specifies that a particular numbered
4755 version of this License "or any later version" applies to it, you
4756 have the option of following the terms and conditions either of
4757 that specified version or of any later version that has been
4758 published (not as a draft) by the Free Software Foundation. If
4759 the Document does not specify a version number of this License,
4760 you may choose any version ever published (not as a draft) by the
4761 Free Software Foundation.
4763 ADDENDUM: How to use this License for your documents
4764 ----------------------------------------------------
4766 To use this License in a document you have written, include a copy of
4767 the License in the document and put the following copyright and license
4768 notices just after the title page:
4770 Copyright (C) YEAR YOUR NAME.
4771 Permission is granted to copy, distribute and/or modify this document
4772 under the terms of the GNU Free Documentation License, Version 1.1
4773 or any later version published by the Free Software Foundation;
4774 with the Invariant Sections being LIST THEIR TITLES, with the
4775 Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
4776 A copy of the license is included in the section entitled ``GNU
4777 Free Documentation License''.
4779 If you have no Invariant Sections, write "with no Invariant Sections"
4780 instead of saying which ones are invariant. If you have no Front-Cover
4781 Texts, write "no Front-Cover Texts" instead of "Front-Cover Texts being
4782 LIST"; likewise for Back-Cover Texts.
4784 If your document contains nontrivial examples of program code, we
4785 recommend releasing these examples in parallel under your choice of
4786 free software license, such as the GNU General Public License, to
4787 permit their use in free software.
4790 File: diff.info, Node: Index, Prev: Copying This Manual, Up: Top
4797 * ! output format: Context.
4798 * +- output format: Unified Format.
4799 * < output format: Normal.
4800 * <<<<<<< for marking conflicts: Marking Conflicts.
4801 * _POSIX2_VERSION: Standards conformance.
4802 * aligning tab stops: Tabs.
4803 * alternate file names: Alternate Names.
4804 * backup file names: Backup Names.
4805 * backup file strategy: Backups.
4806 * binary file diff: Binary.
4807 * blank and tab difference suppression: White Space.
4808 * blank line difference suppression: Blank Lines.
4809 * brief difference reports: Brief.
4810 * bug reports: Bugs.
4811 * C function headings: C Function Headings.
4812 * C if-then-else output format: If-then-else.
4813 * case difference suppression: Case Folding.
4814 * ClearCase: Revision Control.
4815 * cmp invocation: Invoking cmp.
4816 * cmp options: cmp Options.
4817 * columnar output: Side by Side.
4818 * common mistakes with patches: Avoiding Common Mistakes.
4819 * comparing three files: Comparing Three Files.
4820 * conflict: diff3 Merging.
4821 * conflict marking: Marking Conflicts.
4822 * context output format: Context.
4823 * creating files: Creating and Removing.
4824 * diagnostics from patch: patch Messages.
4825 * diff invocation: Invoking diff.
4826 * diff merging: Interactive Merging.
4827 * diff options: diff Options.
4828 * diff sample input: Sample diff Input.
4829 * diff3 hunks: diff3 Hunks.
4830 * diff3 invocation: Invoking diff3.
4831 * diff3 options: diff3 Options.
4832 * diff3 sample input: Sample diff3 Input.
4833 * directories and patch: patch Directories.
4834 * directory structure changes: Changing Structure.
4835 * dry runs for patch: Dry Runs.
4836 * ed script output format: ed Scripts.
4837 * EDITOR: Merge Commands.
4838 * empty files, removing: Creating and Removing.
4839 * exabyte, definition of: cmp Options.
4840 * exbibyte, definition of: cmp Options.
4841 * FDL, GNU Free Documentation License: GNU Free Documentation License.
4842 * file name alternates: Alternate Names.
4843 * file names with unusual characters: Unusual File Names.
4844 * format of diff output: Output Formats.
4845 * format of diff3 output: Comparing Three Files.
4846 * formats for if-then-else line groups: Line Group Formats.
4847 * forward ed script output format: Forward ed.
4848 * full lines: Incomplete Lines.
4849 * function headings, C: C Function Headings.
4850 * fuzz factor when patching: Inexact.
4851 * gibibyte, definition of: cmp Options.
4852 * gigabyte, definition of: cmp Options.
4853 * headings: Sections.
4855 * hunks for diff3: diff3 Hunks.
4856 * if-then-else output format: If-then-else.
4857 * ifdef output format: If-then-else.
4858 * imperfect patch application: Imperfect.
4859 * incomplete line merging: Merging Incomplete Lines.
4860 * incomplete lines: Incomplete Lines.
4861 * inexact patches: Inexact.
4862 * inhibit messages from patch: More or Fewer Messages.
4863 * interactive merging: Interactive Merging.
4864 * introduction: Comparison.
4865 * intuiting file names from patches: Multiple Patches.
4866 * invoking cmp: Invoking cmp.
4867 * invoking diff: Invoking diff.
4868 * invoking diff3: Invoking diff3.
4869 * invoking patch: Invoking patch.
4870 * invoking sdiff: Invoking sdiff.
4871 * keyboard input to patch: patch and Keyboard Input.
4872 * kibibyte, definition of: cmp Options.
4873 * kilobyte, definition of: cmp Options.
4874 * LC_COLLATE: Comparing Directories.
4875 * LC_NUMERIC: Line Group Formats.
4876 * LC_TIME: Detailed Context.
4877 * line formats: Line Formats.
4878 * line group formats: Line Group Formats.
4879 * mebibyte, definition of: cmp Options.
4880 * megabyte, definition of: cmp Options.
4881 * merge commands: Merge Commands.
4882 * merged diff3 format: Bypassing ed.
4883 * merged output format: If-then-else.
4884 * merging from a common ancestor: diff3 Merging.
4885 * merging interactively: Merge Commands.
4886 * messages from patch: patch Messages.
4887 * multibyte characters: Internationalization.
4888 * multiple patches: Multiple Patches.
4889 * newline treatment by diff: Incomplete Lines.
4890 * normal output format: Normal.
4891 * options for cmp: cmp Options.
4892 * options for diff: diff Options.
4893 * options for diff3: diff3 Options.
4894 * options for patch: patch Options.
4895 * options for sdiff: sdiff Options.
4896 * output formats: Output Formats.
4897 * overlap: diff3 Merging.
4898 * overlapping change, selection of: Which Changes.
4899 * overview of diff and patch: Overview.
4900 * paginating diff output: Pagination.
4901 * patch consumer tips: Tips for Patch Consumers.
4902 * patch input format: patch Input.
4903 * patch invocation: Invoking patch.
4904 * patch messages and questions: patch Messages.
4905 * patch options: patch Options.
4906 * patch producer tips: Tips for Patch Producers.
4907 * patch, common mistakes: Avoiding Common Mistakes.
4908 * PATCH_GET: Revision Control.
4909 * PATCH_VERSION_CONTROL: Backup Names.
4910 * patches, shrinking: Generating Smaller Patches.
4911 * patching directories: patch Directories.
4912 * pebibyte, definition of: cmp Options.
4913 * performance of diff: diff Performance.
4914 * petabyte, definition of: cmp Options.
4915 * POSIX <1>: Standards conformance.
4916 * POSIX: patch and POSIX.
4917 * POSIXLY_CORRECT <1>: patch and POSIX.
4918 * POSIXLY_CORRECT: Standards conformance.
4919 * projects for directories: Shortcomings.
4920 * quoting style: patch Quoting Style.
4921 * QUOTING_STYLE: patch Quoting Style.
4922 * RCS: Revision Control.
4923 * RCS script output format: RCS.
4924 * regular expression matching headings: Specified Headings.
4925 * regular expression suppression: Specified Folding.
4926 * reject file names: Reject Names.
4927 * removing empty files: Creating and Removing.
4928 * reporting bugs: Bugs.
4929 * reversed patches: Reversed Patches.
4930 * revision control: Revision Control.
4931 * sample input for diff: Sample diff Input.
4932 * sample input for diff3: Sample diff3 Input.
4933 * SCCS: Revision Control.
4934 * script output formats: Scripts.
4935 * sdiff invocation: Invoking sdiff.
4936 * sdiff options: sdiff Options.
4937 * sdiff output format: sdiff Option Summary.
4938 * section headings: Sections.
4939 * side by side: Side by Side.
4940 * side by side format: Side by Side Format.
4941 * SIMPLE_BACKUP_SUFFIX: Backup Names.
4942 * special files: Special Files.
4943 * specified headings: Specified Headings.
4944 * summarizing which files differ: Brief.
4945 * System V diff3 compatibility: Saving the Changed File.
4946 * tab and blank difference suppression: White Space.
4947 * tab stop alignment: Tabs.
4948 * tebibyte, definition of: cmp Options.
4949 * terabyte, definition of: cmp Options.
4950 * testing patch: Dry Runs.
4951 * text versus binary diff: Binary.
4952 * time stamp format, context diffs: Detailed Context.
4953 * time stamp format, unified diffs: Detailed Unified.
4954 * time stamps on patched files: Patching Time Stamps.
4955 * traditional patch: patch and Tradition.
4956 * two-column output: Side by Side.
4957 * unified output format: Unified Format.
4958 * unmerged change: Which Changes.
4959 * varying-width characters: Internationalization.
4960 * verbose messages from patch: More or Fewer Messages.
4961 * version control: Revision Control.
4962 * VERSION_CONTROL <1>: Backup Names.
4963 * VERSION_CONTROL: Revision Control.
4964 * white space in patches: Changed White Space.
4965 * yottabyte, definition of: cmp Options.
4966 * zettabyte, definition of: cmp Options.
4972 Node: Overview
\7f4045
4973 Node: Comparison
\7f7202
4975 Node: White Space
\7f11313
4976 Node: Blank Lines
\7f12807
4977 Node: Case Folding
\7f13562
4978 Node: Specified Folding
\7f13977
4980 Node: Binary
\7f16295
4981 Node: Output Formats
\7f20358
4982 Node: Sample diff Input
\7f21076
4983 Node: Normal
\7f22569
4984 Node: Detailed Normal
\7f23564
4985 Node: Example Normal
\7f25289
4986 Node: Context
\7f26011
4987 Node: Context Format
\7f27567
4988 Node: Detailed Context
\7f28345
4989 Node: Example Context
\7f30234
4990 Node: Less Context
\7f31748
4991 Node: Unified Format
\7f32894
4992 Node: Detailed Unified
\7f33676
4993 Node: Example Unified
\7f34787
4994 Node: Sections
\7f35807
4995 Node: Specified Headings
\7f36552
4996 Node: C Function Headings
\7f38083
4997 Node: Alternate Names
\7f38908
4998 Node: Side by Side
\7f39808
4999 Node: Side by Side Format
\7f41947
5000 Node: Example Side by Side
\7f42836
5001 Node: Scripts
\7f44162
5002 Node: ed Scripts
\7f44563
5003 Node: Detailed ed
\7f45756
5004 Node: Example ed
\7f47497
5005 Node: Forward ed
\7f47934
5007 Node: If-then-else
\7f49904
5008 Node: Line Group Formats
\7f51572
5009 Node: Line Formats
\7f57437
5010 Node: Detailed If-then-else
\7f60693
5011 Node: Example If-then-else
\7f62583
5012 Node: Incomplete Lines
\7f63632
5013 Node: Comparing Directories
\7f65263
5014 Node: Adjusting Output
\7f69220
5016 Node: Pagination
\7f71177
5017 Node: diff Performance
\7f71626
5018 Node: Comparing Three Files
\7f74708
5019 Node: Sample diff3 Input
\7f75580
5020 Node: Detailed diff3 Normal
\7f76528
5021 Node: diff3 Hunks
\7f78307
5022 Node: Example diff3 Normal
\7f79593
5023 Node: diff3 Merging
\7f80616
5024 Node: Which Changes
\7f82854
5025 Node: Marking Conflicts
\7f84258
5026 Node: Bypassing ed
\7f86714
5027 Node: Merging Incomplete Lines
\7f88068
5028 Node: Saving the Changed File
\7f88784
5029 Node: Interactive Merging
\7f89390
5030 Node: sdiff Option Summary
\7f90094
5031 Node: Merge Commands
\7f91242
5032 Node: Merging with patch
\7f92503
5033 Node: patch Input
\7f94867
5034 Node: Revision Control
\7f95537
5035 Node: Imperfect
\7f96689
5036 Node: Changed White Space
\7f97825
5037 Node: Reversed Patches
\7f98606
5038 Node: Inexact
\7f100056
5039 Node: Dry Runs
\7f103599
5040 Node: Creating and Removing
\7f104447
5041 Node: Patching Time Stamps
\7f105486
5042 Node: Multiple Patches
\7f107677
5043 Node: patch Directories
\7f110328
5044 Node: Backups
\7f111942
5045 Node: Backup Names
\7f112996
5046 Ref: Backup Names-Footnote-1
\7f115955
5047 Node: Reject Names
\7f116082
5048 Node: patch Messages
\7f116660
5049 Node: More or Fewer Messages
\7f117706
5050 Node: patch and Keyboard Input
\7f118319
5051 Node: patch Quoting Style
\7f119332
5052 Node: patch and POSIX
\7f120464
5053 Node: patch and Tradition
\7f121290
5054 Node: Making Patches
\7f124734
5055 Node: Tips for Patch Producers
\7f125552
5056 Node: Tips for Patch Consumers
\7f126796
5057 Node: Avoiding Common Mistakes
\7f127421
5058 Node: Generating Smaller Patches
\7f129934
5059 Node: Invoking cmp
\7f131683
5060 Node: cmp Options
\7f132532
5061 Node: Invoking diff
\7f135896
5062 Node: diff Options
\7f137599
5063 Node: Invoking diff3
\7f145722
5064 Node: diff3 Options
\7f146352
5065 Node: Invoking patch
\7f149255
5066 Node: patch Options
\7f150455
5067 Node: Invoking sdiff
\7f155669
5068 Node: sdiff Options
\7f156808
5069 Node: Standards conformance
\7f159561
5070 Node: Projects
\7f161299
5071 Node: Shortcomings
\7f162002
5072 Node: Internationalization
\7f163092
5073 Node: Changing Structure
\7f164247
5074 Node: Special Files
\7f165336
5075 Node: Unusual File Names
\7f166282
5076 Node: Time Stamp Order
\7f166904
5077 Node: Ignoring Changes
\7f167531
5078 Node: Speedups
\7f168285
5080 Node: Copying This Manual
\7f169574
5081 Node: GNU Free Documentation License
\7f169782
5082 Node: Index
\7f189646