diff Output Formats
diff Output Prettier
diff Performance Tradeoffs
sdiff
patch
cmp
diff
diff3
patch
sdiff
diff Output Formats
diff Output Prettier
diff Performance Tradeoffs
sdiff
patch
patch Input Format
patch
patch and the POSIX Standard
patch and Traditional patch
cmp
diff
diff3
patch
sdiff
diff, diff3,
sdiff, and cmp commands for showing the
differences between files and the GNU patch command for
using their output to update files.
Copyright © 1992, 1993, 1994, 1998, 2001, 2002 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections, with the Front-Cover texts being "A GNU Manual," and with the Back-Cover Texts as in (a) below. A copy of the license is included in the section entitled "GNU Free Documentation License."(a) The FSF's Back-Cover Text is: "You have freedom to copy and modify this GNU Manual, like GNU software. Copies published by the Free Software Foundation raise funds for GNU development."
diff output prettier.
diff smarter or faster.
sdiff.
patch to change old files into new ones.
Computer users often find occasion to ask how two files differ. Perhaps one file is a newer version of the other file. Or maybe the two files started out as identical copies but were changed by different people.
You can use the diff command to show differences between two
files, or each corresponding file in two directories. diff
outputs differences between files line by line in any of several
formats, selectable by command line options. This set of differences is
often called a diff or patch. For files that are identical,
diff normally produces no output; for binary (non-text) files,
diff normally reports only that they are different.
You can use the cmp command to show the byte and line numbers
where two files differ. cmp can also show all the bytes
that differ between the two files, side by side. A way to compare
two files character by character is the Emacs command M-x
compare-windows. See Other Window, for more information on that command.
You can use the diff3 command to show differences among three
files. When two people have made independent changes to a common
original, diff3 can report the differences between the original
and the two changed versions, and can produce a merged file that
contains both persons' changes together with warnings about conflicts.
You can use the sdiff command to merge two files interactively.
You can use the set of differences produced by diff to distribute
updates to text files (such as program source code) to other people.
This method is especially useful when the differences are small compared
to the complete files. Given diff output, you can use the
patch program to update, or patch, a copy of the file. If you
think of diff as subtracting one file from another to produce
their difference, you can think of patch as adding the difference
to one file to reproduce the other.
This manual first concentrates on making diffs, and later shows how to use diffs to update files.
GNU diff was written by Paul Eggert, Mike Haertel,
David Hayes, Richard Stallman, and Len Tower. Wayne Davison designed and
implemented the unified output format. The basic algorithm is described
in "An O(ND) Difference Algorithm and its Variations", Eugene W. Myers,
Algorithmica Vol. 1 No. 2, 1986, pp. 251-266; and in "A File
Comparison Program", Webb Miller and Eugene W. Myers,
Software--Practice and Experience Vol. 15 No. 11, 1985,
pp. 1025-1040.
The algorithm was independently discovered as described in
"Algorithms for Approximate String Matching",
E. Ukkonen, Information and Control Vol. 64, 1985, pp. 100-118.
GNU diff3 was written by Randy Smith. GNU
sdiff was written by Thomas Lord. GNU cmp
was written by Torbjorn Granlund and David MacKenzie.
patch was written mainly by Larry Wall and Paul Eggert;
several GNU enhancements were contributed by Wayne Davison and
David MacKenzie. Parts of this manual are adapted from a manual page
written by Larry Wall, with his permission.
There are several ways to think about the differences between two files.
One way to think of the differences is as a series of lines that were
deleted from, inserted in, or changed in one file to produce the other
file. diff compares two files line by line, finds groups of
lines that differ, and reports each group of differing lines. It can
report the differing lines in several formats, which have different
purposes.
GNU diff can show whether files are different without detailing
the differences. It also provides ways to suppress certain kinds of
differences that are not important to you. Most commonly, such
differences are changes in the amount of white space between words or
lines. diff also provides ways to suppress differences in
alphabetic case or in lines that match a regular expression that you
provide. These options can accumulate; for example, you can ignore
changes in both white space and alphabetic case.
Another way to think of the differences between two files is as a
sequence of pairs of bytes that can be either identical or
different. cmp reports the differences between two files
byte by byte, instead of line by line. As a result, it is often
more useful than diff for comparing binary files. For text
files, cmp is useful mainly when you want to know only whether
two files are identical, or whether one file is a prefix of the other.
To illustrate the effect that considering changes byte by byte
can have compared with considering them line by line, think of what
happens if a single newline character is added to the beginning of a
file. If that file is then compared with an otherwise identical file
that lacks the newline at the beginning, diff will report that a
blank line has been added to the file, while cmp will report that
almost every byte of the two files differs.
diff3 normally compares three input files line by line, finds
groups of lines that differ, and reports each group of differing lines.
Its output is designed to make it easy to inspect two different sets of
changes to the same file.
When comparing two files, diff finds sequences of lines common to
both files, interspersed with groups of differing lines called
hunks. Comparing two identical files yields one sequence of
common lines and no hunks, because no lines differ. Comparing two
entirely different files yields no common lines and one large hunk that
contains all lines of both files. In general, there are many ways to
match up lines between two given files. diff tries to minimize
the total hunk size by finding large sequences of common lines
interspersed with small hunks of differing lines.
For example, suppose the file F contains the three lines
a, b, c, and the file G contains the same
three lines in reverse order c, b, a. If
diff finds the line c as common, then the command
diff F G produces this output:
1,2d0 < a < b 3a2,3 > b > a
But if diff notices the common line b instead, it produces
this output:
1c1 < a --- > c 3c3 < c --- > a
It is also possible to find a as the common line. diff
does not always find an optimal matching between the files; it takes
shortcuts to run faster. But its output is usually close to the
shortest possible. You can adjust this tradeoff with the
--minimal option (see diff Performance).
The -E and --ignore-tab-expansion options ignore the
distinction between tabs and spaces on input. A tab is considered to be
equivalent to the number of spaces to the next tab stop. diff
assumes that tab stops are set every 8 print columns.
The -b and --ignore-space-change options are stronger.
They ignore white space at line end, and consider all other sequences of
one or more white space characters to be equivalent. With these
options, diff considers the following two lines to be equivalent,
where $ denotes the line end:
Here lyeth muche rychnesse in lytell space. -- John Heywood$ Here lyeth muche rychnesse in lytell space. -- John Heywood $
The -w and --ignore-all-space options are stronger still.
They ignore difference even if one line has white space where
the other line has none. White space characters include
tab, newline, vertical tab, form feed, carriage return, and space;
some locales may define additional characters to be white space.
With these options, diff considers the
following two lines to be equivalent, where $ denotes the line
end and ^M denotes a carriage return:
Here lyeth muche rychnesse in lytell space.-- John Heywood$ He relyeth much erychnes seinly tells pace. --John Heywood ^M$
The -B and --ignore-blank-lines options ignore insertions
or deletions of blank lines. These options affect only lines
that are completely empty; they do not affect lines that look empty but
contain space or tab characters. With these options, for example, a
file containing
1. A point is that which has no part. 2. A line is breadthless length. -- Euclid, The Elements, I
is considered identical to a file containing
1. A point is that which has no part. 2. A line is breadthless length. -- Euclid, The Elements, I
GNU diff can treat lower case letters as equivalent to their
upper case counterparts, so that, for example, it considers Funky
Stuff, funky STUFF, and fUNKy stuFf to all be the same.
To request this, use the -i or --ignore-case option.
To ignore insertions and deletions of lines that match a
grep-style regular expression, use the -I
regexp or --ignore-matching-lines=regexp option.
You should escape
regular expressions that contain shell metacharacters to prevent the
shell from expanding them. For example, diff -I '^[[:digit:]]' ignores
all changes to lines beginning with a digit.
However, -I only ignores the insertion or deletion of lines that
contain the regular expression if every changed line in the hunk--every
insertion and every deletion--matches the regular expression. In other
words, for each nonignorable change, diff prints the complete set
of changes in its vicinity, including the ignorable ones.
You can specify more than one regular expression for lines to ignore by
using more than one -I option. diff tries to match each
line against each regular expression.
When you only want to find out whether files are different, and you
don't care what the differences are, you can use the summary output
format. In this format, instead of showing the differences between the
files, diff simply reports whether files differ. The -q
and --brief options select this output format.
This format is especially useful when comparing the contents of two
directories. It is also much faster than doing the normal line by line
comparisons, because diff can stop analyzing the files as soon as
it knows that there are any differences.
You can also get a brief indication of whether two files differ by using
cmp. For files that are identical, cmp produces no
output. When the files differ, by default, cmp outputs the byte
and line number where the first difference occurs. You can use
the -s option to suppress that information, so that cmp
produces no output and reports whether the files differ using only its
exit status (see Invoking cmp).
Unlike diff, cmp cannot compare directories; it can only
compare two files.
If diff thinks that either of the two files it is comparing is
binary (a non-text file), it normally treats that pair of files much as
if the summary output format had been selected (see Brief), and
reports only that the binary files are different. This is because line
by line comparisons are usually not meaningful for binary files.
diff determines whether a file is text or binary by checking the
first few bytes in the file; the exact number of bytes is system
dependent, but it is typically several thousand. If every byte in
that part of the file is non-null, diff considers the file to be
text; otherwise it considers the file to be binary.
Sometimes you might want to force diff to consider files to be
text. For example, you might be comparing text files that contain
null characters; diff would erroneously decide that those are
non-text files. Or you might be comparing documents that are in a
format used by a word processing system that uses null characters to
indicate special formatting. You can force diff to consider all
files to be text files, and compare them line by line, by using the
-a or --text option. If the files you compare using this
option do not in fact contain text, they will probably contain few
newline characters, and the diff output will consist of hunks
showing differences between long lines of whatever characters the files
contain.
You can also force diff to consider all files to be binary files,
and report only whether they differ (but not how). Use the
-q or --brief option for this.
Differing binary files are considered to cause trouble because the
resulting diff output does not capture all the differences.
This trouble causes diff to exit with status 2. However,
this trouble cannot occur with the --a or --text
option, or with the -q or --brief option, as these
options both cause diff to treat binary files like text
files.
In operating systems that distinguish between text and binary files,
diff normally reads and writes all data as text. Use the
--binary option to force diff to read and write binary
data instead. This option has no effect on a POSIX-compliant system
like GNU or traditional Unix. However, many personal computer
operating systems represent the end of a line with a carriage return
followed by a newline. On such systems, diff normally ignores
these carriage returns on input and generates them at the end of each
output line, but with the --binary option diff treats
each carriage return as just another input character, and does not
generate a carriage return at the end of each output line. This can be
useful when dealing with non-text files that are meant to be
interchanged with POSIX-compliant systems.
The --strip-trailing-cr causes diff to treat input
lines that end in carriage return followed by newline as if they end
in plain newline. This can be useful when comparing text that is
imperfectly imported from many personal computer operating systems.
This option affects how lines are read, which in turn affects how they
are compared and output.
If you want to compare two files byte by byte, you can use the
cmp program with the -l option to show the values
of each differing byte in the two files. With GNU cmp,
you can also use the -b option to show the ASCII
representation of those bytes. See Invoking cmp, for more
information.
If diff3 thinks that any of the files it is comparing is binary
(a non-text file), it normally reports an error, because such
comparisons are usually not useful. diff3 uses the same test as
diff to decide whether a file is binary. As with diff, if
the input files contain a few non-text bytes but otherwise are like
text files, you can force diff3 to consider all files to be text
files and compare them line by line by using the -a or
--text options.
diff Output Formatsdiff has several mutually exclusive options for output format.
The following sections describe each format, illustrating how
diff reports the differences between two sample input files.
diff input files for examples.
Here are two sample files that we will use in numerous examples to
illustrate the output of diff and how various options can change
it.
This is the file lao:
The Way that can be told of is not the eternal Way; The name that can be named is not the eternal name. The Nameless is the origin of Heaven and Earth; The Named is the mother of all things. Therefore let there always be non-being, so we may see their subtlety, And let there always be being, so we may see their outcome. The two are the same, But after they are produced, they have different names.
This is the file tzu:
The Nameless is the origin of Heaven and Earth; The named is the mother of all things. Therefore let there always be non-being, so we may see their subtlety, And let there always be being, so we may see their outcome. The two are the same, But after they are produced, they have different names. They both may be called deep and profound. Deeper and more profound, The door of all subtleties!
In this example, the first hunk contains just the first two lines of
lao, the second hunk contains the fourth line of lao
opposing the second and third lines of tzu, and the last hunk
contains just the last three lines of tzu.
The "normal" diff output format shows each hunk of differences
without any surrounding context. Sometimes such output is the clearest
way to see how lines have changed, without the clutter of nearby
unchanged lines (although you can get similar results with the context
or unified formats by using 0 lines of context). However, this format
is no longer widely used for sending out patches; for that purpose, the
context format (see Context Format) and the unified format
(see Unified Format) are superior. Normal format is the default for
compatibility with older versions of diff and the POSIX
standard. Use the --normal option to select this output
format explicitly.
The normal output format consists of one or more hunks of differences;
each hunk shows one area where the files differ. Normal format hunks
look like this:
change-command < from-file-line < from-file-line... --- > to-file-line > to-file-line...
There are three types of change commands. Each consists of a line number or comma-separated range of lines in the first file, a single character indicating the kind of change to make, and a line number or comma-separated range of lines in the second file. All line numbers are the original line numbers in each file. The types of change commands are:
lar
8a12,15 means append lines 12-15
of file 2 after line 8 of file 1; or, if changing file 2 into file 1,
delete lines 12-15 of file 2.
fct
5,7c8,10 means change lines 5-7 of
file 1 to read as lines 8-10 of file 2; or, if changing file 2 into
file 1, change lines 8-10 of file 2 to read as lines 5-7 of file 1.
rdl
5,7d3 means delete lines 5-7 of file 1; or, if
changing file 2 into file 1, append lines 5-7 of file 1 after line 3 of
file 2.
Here is the output of the command diff lao tzu
(see Sample diff Input, for the complete contents of the two files).
Notice that it shows only the lines that are different between the two
files.
1,2d0 < The Way that can be told of is not the eternal Way; < The name that can be named is not the eternal name. 4c2,3 < The Named is the mother of all things. --- > The named is the mother of all things. > 11a11,13 > They both may be called deep and profound. > Deeper and more profound, > The door of all subtleties!
Usually, when you are looking at the differences between files, you will also want to see the parts of the files near the lines that differ, to help you understand exactly what has changed. These nearby parts of the files are called the context.
GNU diff provides two output formats that show context
around the differing lines: context format and unified
format. It can optionally show in which function or section of the
file the differing lines are found.
If you are distributing new versions of files to other people in the
form of diff output, you should use one of the output formats
that show context so that they can apply the diffs even if they have
made small changes of their own to the files. patch can apply
the diffs in this case by searching in the files for the lines of
context around the differing lines; if those lines are actually a few
lines away from where the diff says they are, patch can adjust
the line numbers accordingly and still apply the diff correctly.
See Imperfect, for more information on using patch to apply
imperfect diffs.
The context output format shows several lines of context around the lines that differ. It is the standard format for distributing updates to source code.
To select this output format, use the -C lines,
--context[=lines], or -c option. The
argument lines that some of these options take is the number of
lines of context to show. If you do not specify lines, it
defaults to three. For proper operation, patch typically needs
at least two lines of context.
The context output format starts with a two-line header, which looks
like this:
*** from-file from-file-modification-time --- to-file to-file-modification time
The time stamp normally looks like 2002-02-21 23:30:39.942229878
-0800 to indicate the date, time with fractional seconds, and time
zone in Internet RFC 2822 format. However, a traditional time stamp like Thu Feb 21
23:30:39 2002 is used if the LC_TIME locale category is either
C or POSIX.
You can change the header's content with the
--label=label option; see Alternate Names.
Next come one or more hunks of differences; each hunk shows one area
where the files differ. Context format hunks look like this:
*************** *** from-file-line-range **** from-file-line from-file-line... --- to-file-line-range ---- to-file-line to-file-line...
The lines of context around the lines that differ start with two space characters. The lines that differ between the two files start with one of the following indicator characters, followed by a space character:
!
! in the part of this hunk for the other file.
+
-
If all of the changes in a hunk are insertions, the lines of from-file are omitted. If all of the changes are deletions, the lines of to-file are omitted.
Here is the output of diff -c lao tzu (see Sample diff Input,
for the complete contents of the two files). Notice that up to three
lines that are not different are shown around each line that is
different; they are the context lines. Also notice that the first two
hunks have run together, because their contents overlap.
*** lao 2002-02-21 23:30:39.942229878 -0800
--- tzu 2002-02-21 23:30:50.442260588 -0800
***************
*** 1,7 ****
- The Way that can be told of is not the eternal Way;
- The name that can be named is not the eternal name.
The Nameless is the origin of Heaven and Earth;
! The Named is the mother of all things.
Therefore let there always be non-being,
so we may see their subtlety,
And let there always be being,
--- 1,6 ----
The Nameless is the origin of Heaven and Earth;
! The named is the mother of all things.
!
Therefore let there always be non-being,
so we may see their subtlety,
And let there always be being,
***************
*** 9,11 ****
--- 8,13 ----
The two are the same,
But after they are produced,
they have different names.
+ They both may be called deep and profound.
+ Deeper and more profound,
+ The door of all subtleties!
Here is the output of diff -C 1 lao tzu (see Sample diff Input, for the complete contents of the two files). Notice that at
most one context line is reported here.
*** lao 2002-02-21 23:30:39.942229878 -0800
--- tzu 2002-02-21 23:30:50.442260588 -0800
***************
*** 1,5 ****
- The Way that can be told of is not the eternal Way;
- The name that can be named is not the eternal name.
The Nameless is the origin of Heaven and Earth;
! The Named is the mother of all things.
Therefore let there always be non-being,
--- 1,4 ----
The Nameless is the origin of Heaven and Earth;
! The named is the mother of all things.
!
Therefore let there always be non-being,
***************
*** 11 ****
--- 10,13 ----
they have different names.
+ They both may be called deep and profound.
+ Deeper and more profound,
+ The door of all subtleties!
The unified output format is a variation on the context format that is
more compact because it omits redundant context lines. To select this
output format, use the -U lines,
--unified[=lines], or -u
option. The argument lines is the number of lines of context to
show. When it is not given, it defaults to three.
At present, only GNU diff can produce this format and
only GNU patch can automatically apply diffs in this
format. For proper operation, patch typically needs at
least three lines of context.
The unified output format starts with a two-line header, which looks
like this:
--- from-file from-file-modification-time +++ to-file to-file-modification-time
The time stamp looks like 2002-02-21 23:30:39.942229878 -0800
to indicate the date, time with fractional seconds, and time zone.
You can change the header's content with the
--label=label option; see See Alternate Names.
Next come one or more hunks of differences; each hunk shows one area
where the files differ. Unified format hunks look like this:
@@ from-file-range to-file-range @@ line-from-either-file line-from-either-file...
The lines common to both files begin with a space character. The lines that actually differ between the two files have one of the following indicator characters in the left print column:
+
-
Here is the output of the command diff -u lao tzu
(see Sample diff Input, for the complete contents of the two files):
--- lao 2002-02-21 23:30:39.942229878 -0800 +++ tzu 2002-02-21 23:30:50.442260588 -0800 @@ -1,7 +1,6 @@ -The Way that can be told of is not the eternal Way; -The name that can be named is not the eternal name. The Nameless is the origin of Heaven and Earth; -The Named is the mother of all things. +The named is the mother of all things. + Therefore let there always be non-being, so we may see their subtlety, And let there always be being, @@ -9,3 +8,6 @@ The two are the same, But after they are produced, they have different names. +They both may be called deep and profound. +Deeper and more profound, +The door of all subtleties!
Sometimes you might want to know which part of the files each change
falls in. If the files are source code, this could mean which function
was changed. If the files are documents, it could mean which chapter or
appendix was changed. GNU diff can show this by displaying the
nearest section heading line that precedes the differing lines. Which
lines are "section headings" is determined by a regular expression.
To show in which sections differences occur for files that are not
source code for C or similar languages, use the -F regexp
or --show-function-line=regexp option. diff
considers lines that match the grep-style regular expression
regexp to be the beginning
of a section of the file. Here are suggested regular expressions for
some common languages:
^[[:alpha:]$_]
^(
^@node
This option does not automatically select an output format; in order to use it, you must select the context format (see Context Format) or unified format (see Unified Format). In other output formats it has no effect.
The -F and --show-function-line options find the nearest
unchanged line that precedes each hunk of differences and matches the
given regular expression. Then they add that line to the end of the
line of asterisks in the context format, or to the @@ line in
unified format. If no matching line exists, they leave the output for
that hunk unchanged. If that line is more than 40 characters long, they
output only the first 40 characters. You can specify more than one
regular expression for such lines; diff tries to match each line
against each regular expression, starting with the last one given. This
means that you can use -p and -F together, if you wish.
To show in which functions differences occur for C and similar
languages, you can use the -p or --show-c-function option.
This option automatically defaults to the context output format
(see Context Format), with the default number of lines of context.
You can override that number with -C lines elsewhere in the
command line. You can override both the format and the number with
-U lines elsewhere in the command line.
The -p and --show-c-function options are equivalent to
-F '^[[:alpha:]$_]' if the unified format is specified, otherwise
-c -F '^[[:alpha:]$_]' (see Specified Headings). GNU
diff provides them for the sake of convenience.
If you are comparing two files that have meaningless or uninformative
names, you might want diff to show alternate names in the header
of the context and unified output formats. To do this, use the
--label=label option. The first time
you give this option, its argument replaces the name and date of the
first file in the header; the second time, its argument replaces the
name and date of the second file. If you give this option more than
twice, diff reports an error. The --label option does not
affect the file names in the pr header when the -l or
--paginate option is used (see Pagination).
Here are the first two lines of the output from diff -C 2
--label=original --label=modified lao tzu:
*** original --- modified
diff can produce a side by side difference listing of two files.
The files are listed in two columns with a gutter between them. The
gutter contains one of the following markers:
--ignore options (see White Space).
|
<
>
(
)
\
/
Normally, an output line is incomplete if and only if the lines that it
contains are incomplete; See Incomplete Lines. However, when an
output line represents two differing lines, one might be incomplete
while the other is not. In this case, the output line is complete,
but its the gutter is marked \ if the first line is incomplete,
/ if the second line is.
Side by side format is sometimes easiest to read, but it has limitations. It generates much wider output than usual, and truncates lines that are too long to fit. Also, it relies on lining up output more heavily than usual, so its output looks particularly bad if you use varying width fonts, nonstandard tab stops, or nonprinting characters.
You can use the sdiff command to interactively merge side by side
differences. See Interactive Merging, for more information on merging files.
The -y or --side-by-side option selects side by side
format. Because side by side output lines contain two input lines, the
output is wider than usual: normally 130 print columns, which can fit
onto a traditional printer line. You can set the width of the output
with the -W columns or --width=columns
option. The output is split into two halves of equal width, separated by a
small gutter to mark differences; the right half is aligned to a tab
stop so that tabs line up. Input lines that are too long to fit in half
of an output line are truncated for output.
The --left-column option prints only the left column of two
common lines. The --suppress-common-lines option suppresses
common lines entirely.
Here is the output of the command diff -y -W 72 lao tzu
(see Sample diff Input, for the complete contents of the two files).
The Way that can be told of is n <
The name that can be named is no <
The Nameless is the origin of He The Nameless is the origin of He
The Named is the mother of all t | The named is the mother of all t
>
Therefore let there always be no Therefore let there always be no
so we may see their subtlety, so we may see their subtlety,
And let there always be being, And let there always be being,
so we may see their outcome. so we may see their outcome.
The two are the same, The two are the same,
But after they are produced, But after they are produced,
they have different names. they have different names.
> They both may be called deep and
> Deeper and more profound,
> The door of all subtleties!
Several output modes produce command scripts for editing from-file to produce to-file.
diff to produce commands for ed.
ed scripts.
diff output format used by RCS.
ed Scriptsdiff can produce commands that direct the ed text editor
to change the first file into the second file. Long ago, this was the
only output mode that was suitable for editing one file into another
automatically; today, with patch, it is almost obsolete. Use the
-e or --ed option to select this output format.
Like the normal format (see Normal), this output format does not show any context; unlike the normal format, it does not include the information necessary to apply the diff in reverse (to produce the first file if all you have is the second file and the diff).
If the file d contains the output of diff -e old new, then
the command (cat d && echo w) | ed - old edits old to make
it a copy of new. More generally, if d1, d2,
..., dN contain the outputs of diff -e old new1,
diff -e new1 new2, ..., diff -e newN-1 newN,
respectively, then the command (cat d1 d2 ... dN && echo w) |
ed - old edits old to make it a copy of newN.
ed format.
ed script.
ed FormatThe ed output format consists of one or more hunks of
differences. The changes closest to the ends of the files come first so
that commands that change the number of lines do not affect how
ed interprets line numbers in succeeding commands. ed
format hunks look like this:
change-command to-file-line to-file-line... .
Because ed uses a single period on a line to indicate the end of
input, GNU diff protects lines of changes that contain a single
period on a line by writing two periods instead, then writing a
subsequent ed command to change the two periods into one. The
ed format cannot represent an incomplete line, so if the second
file ends in a changed incomplete line, diff reports an error and
then pretends that a newline was appended.
There are three types of change commands. Each consists of a line number or comma-separated range of lines in the first file and a single character indicating the kind of change to make. All line numbers are the original line numbers in the file. The types of change commands are:
la
8a means to add the following lines after line 8 of file
1.
rc
5,7c means change lines 5-7 of file 1 to read as the text file
2.
rd
5,7d means delete lines 5-7 of file 1.
ed ScriptHere is the output of diff -e lao tzu (see Sample diff Input, for the complete contents of the two files):
11a They both may be called deep and profound. Deeper and more profound, The door of all subtleties! . 4c The named is the mother of all things. . 1,2d
ed Scriptsdiff can produce output that is like an ed script, but
with hunks in forward (front to back) order. The format of the commands
is also changed slightly: command characters precede the lines they
modify, spaces separate line numbers in ranges, and no attempt is made
to disambiguate hunk lines consisting of a single period. Like
ed format, forward ed format cannot represent incomplete
lines.
Forward ed format is not very useful, because neither ed
nor patch can apply diffs in this format. It exists mainly for
compatibility with older versions of diff. Use the -f or
--forward-ed option to select it.
The RCS output format is designed specifically for use by the Revision
Control System, which is a set of free programs used for organizing
different versions and systems of files. Use the -n or
--rcs option to select this output format. It is like the
forward ed format (see Forward ed), but it can represent
arbitrary changes to the contents of a file because it avoids the
forward ed format's problems with lines consisting of a single
period and with incomplete lines. Instead of ending text sections with
a line consisting of a single period, each command specifies the number
of lines it affects; a combination of the a and d
commands are used instead of c. Also, if the second file ends
in a changed incomplete line, then the output also ends in an
incomplete line.
Here is the output of diff -n lao tzu (see Sample diff Input, for the complete contents of the two files):
d1 2 d4 1 a4 2 The named is the mother of all things. a11 3 They both may be called deep and profound. Deeper and more profound, The door of all subtleties!
You can use diff to merge two files of C source code. The output
of diff in this format contains all the lines of both files.
Lines common to both files are output just once; the differing parts are
separated by the C preprocessor directives #ifdef name or
#ifndef name, #else, and #endif. When
compiling the output, you select which version to use by either defining
or leaving undefined the macro name.
To merge two files, use diff with the -D name or
--ifdef=name option. The argument name is the C
preprocessor identifier to use in the #ifdef and #ifndef
directives.
For example, if you change an instance of wait (&s) to
waitpid (-1, &s, 0) and then merge the old and new files with
the --ifdef=HAVE_WAITPID option, then the affected part of your code
might look like this:
do {
#ifndef HAVE_WAITPID
if ((w = wait (&s)) < 0 && errno != EINTR)
#else /* HAVE_WAITPID */
if ((w = waitpid (-1, &s, 0)) < 0 && errno != EINTR)
#endif /* HAVE_WAITPID */
return w;
} while (w != child);
You can specify formats for languages other than C by using line group formats and line formats, as described in the next sections.
Line group formats let you specify formats suitable for many applications that allow if-then-else input, including programming languages and text formatting languages. A line group format specifies the output format for a contiguous group of similar lines.
For example, the following command compares the TeX files old
and new, and outputs a merged file in which old regions are
surrounded by \begin{em}-\end{em} lines, and new
regions are surrounded by \begin{bf}-\end{bf} lines.
diff \
--old-group-format='\begin{em}
%<\end{em}
' \
--new-group-format='\begin{bf}
%>\end{bf}
' \
old new
The following command is equivalent to the above example, but it is a
little more verbose, because it spells out the default line group formats.
diff \
--old-group-format='\begin{em}
%<\end{em}
' \
--new-group-format='\begin{bf}
%>\end{bf}
' \
--unchanged-group-format='%=' \
--changed-group-format='\begin{em}
%<\end{em}
\begin{bf}
%>\end{bf}
' \
old new
Here is a more advanced example, which outputs a diff listing with
headers containing line numbers in a "plain English" style.
diff \ --unchanged-group-format='' \ --old-group-format='-------- %dn line%(n=1?:s) deleted at %df: %<' \ --new-group-format='-------- %dN line%(N=1?:s) added after %de: %>' \ --changed-group-format='-------- %dn line%(n=1?:s) changed at %df: %<-------- to: %>' \ old new
To specify a line group format, use diff with one of the options
listed below. You can specify up to four line group formats, one for
each kind of line group. You should quote format, because it
typically contains shell metacharacters.
--old-group-format=format
--new-group-format=format
--changed-group-format=format
--unchanged-group-format=format
In a line group format, ordinary characters represent themselves;
conversion specifications start with % and have one of the
following forms.
%<
%>
%=
%%
%.
%c'C'
%c':' stands for a colon, even inside
the then-part of an if-then-else format, which a colon would
normally terminate.
%c'\O'
%c'\0' stands for a null character.
Fn
printf conversion specification and n is one
of the following letters, stands for n's value formatted with F.
e
f
l
m
n
E, F, L, M, N
The printf conversion specification can be %d,
%o, %x, or %X, specifying decimal, octal,
lower case hexadecimal, or upper case hexadecimal output
respectively. After the % the following options can appear in
sequence: a series of zero or more flags; an integer
specifying the minimum field width; and a period followed by an
optional integer specifying the minimum number of digits.
The flags are - for left-justification, ' for separating
the digit into groups as specified by the LC_NUMERIC locale category,
and 0 for padding with zeros instead of spaces.
For example, %5dN prints the number of new lines in the group
in a field of width 5 characters, using the printf format "%5d".
(A=B?T:E)
For example, %(N=0?no:%dN) line%(N=1?:s) is equivalent to
no lines if N (the number of lines in the group in the the
new file) is 0, to 1 line if N is 1, and to %dN lines
otherwise.
Line formats control how each line taken from an input file is output as part of a line group in if-then-else format.
For example, the following command outputs text with a one-character
change indicator to the left of the text. The first character of output
is - for deleted lines, | for added lines, and a space for
unchanged lines. The formats contain newline characters where newlines
are desired on output.
diff \ --old-line-format='-%l ' \ --new-line-format='|%l ' \ --unchanged-line-format=' %l ' \ old new
To specify a line format, use one of the following options. You should quote format, since it often contains shell metacharacters.
--old-line-format=format
--new-line-format=format
--unchanged-line-format=format
--line-format=format
In a line format, ordinary characters represent themselves;
conversion specifications start with % and have one of the
following forms.
%l
%L
%%
%.
%c'C'
%c':' stands for a colon.
%c'\O'
%c'\0' stands for a null character.
Fn
printf conversion specification,
stands for the line number formatted with F.
For example, %.5dn prints the line number using the
printf format "%.5d". See Line Group Formats, for
more about printf conversion specifications.
The default line format is %l followed by a newline character.
If the input contains tab characters and it is important that they line
up on output, you should ensure that %l or %L in a line
format is just after a tab stop (e.g. by preceding %l or
%L with a tab character), or you should use the -t or
--expand-tabs option.
Taken together, the line and line group formats let you specify many
different formats. For example, the following command uses a format
similar to normal diff format. You can tailor this command
to get fine control over diff output.
diff \ --old-line-format='< %l ' \ --new-line-format='> %l ' \ --old-group-format='%df%(f=l?:,%dl)d%dE %<' \ --new-group-format='%dea%dF%(F=L?:,%dL) %>' \ --changed-group-format='%df%(f=l?:,%dl)c%dF%(F=L?:,%dL) %<--- %>' \ --unchanged-group-format='' \ old new
For lines common to both files, diff uses the unchanged line
group format. For each hunk of differences in the merged output
format, if the hunk contains only lines from the first file,
diff uses the old line group format; if the hunk contains only
lines from the second file, diff uses the new group format;
otherwise, diff uses the changed group format.
The old, new, and unchanged line formats specify the output format of lines from the first file, lines from the second file, and lines common to both files, respectively.
The option --ifdef=name is equivalent to
the following sequence of options using shell syntax:
--old-group-format='#ifndef name %<#endif /* ! name */ ' \ --new-group-format='#ifdef name %>#endif /* name */ ' \ --unchanged-group-format='%=' \ --changed-group-format='#ifndef name %<#else /* name */ %>#endif /* name */ '
You should carefully check the diff output for proper nesting.
For example, when using the -D name or
--ifdef=name option, you should check that if the
differing lines contain any of the C preprocessor directives
#ifdef, #ifndef, #else, #elif, or
#endif, they are nested properly and match. If they don't, you
must make corrections manually. It is a good idea to carefully check
the resulting code anyway to make sure that it really does what you
want it to; depending on how the input files were produced, the output
might contain duplicate or otherwise incorrect code.
The patch -D name option behaves like
the diff -D name option, except it operates on
a file and a diff to produce a merged file; See patch Options.
Here is the output of diff -DTWO lao tzu (see Sample diff Input, for the complete contents of the two files):
#ifndef TWO The Way that can be told of is not the eternal Way; The name that can be named is not the eternal name. #endif /* ! TWO */ The Nameless is the origin of Heaven and Earth; #ifndef TWO The Named is the mother of all things. #else /* TWO */ The named is the mother of all things. #endif /* TWO */ Therefore let there always be non-being, so we may see their subtlety, And let there always be being, so we may see their outcome. The two are the same, But after they are produced, they have different names. #ifdef TWO They both may be called deep and profound. Deeper and more profound, The door of all subtleties! #endif /* TWO */
When an input file ends in a non-newline character, its last line is called an incomplete line because its last character is not a newline. All other lines are called full lines and end in a newline character. Incomplete lines do not match full lines unless differences in white space are ignored (see White Space).
An incomplete line is normally distinguished on output from a full line
by a following line that starts with \. However, the RCS format
(see RCS) outputs the incomplete line as-is, without any trailing
newline or following line. The side by side format normally represents
incomplete lines as-is, but in some cases uses a \ or /
gutter marker; See Side by Side. The if-then-else line format
preserves a line's incompleteness with %L, and discards the
newline with %l; See Line Formats. Finally, with the
ed and forward ed output formats (see Output Formats)
diff cannot represent an incomplete line, so it pretends there
was a newline and reports an error.
For example, suppose F and G are one-byte files that
contain just f and g, respectively. Then diff F G
outputs
1c1 < f \ No newline at end of file --- > g \ No newline at end of file
(The exact message may differ in non-English locales.)
diff -n F G outputs the following without a trailing newline:
d1 1 a1 1 g
diff -e F G reports two errors and outputs the following:
1c g .
You can use diff to compare some or all of the files in two
directory trees. When both file name arguments to diff are
directories, it compares each file that is contained in both
directories, examining file names in alphabetical order as specified by
the LC_COLLATE locale category. Normally
diff is silent about pairs of files that contain no differences,
but if you use the -s or --report-identical-files option,
it reports pairs of identical files. Normally diff reports
subdirectories common to both directories without comparing
subdirectories' files, but if you use the -r or
--recursive option, it compares every corresponding pair of files
in the directory trees, as many levels deep as they go.
For file names that are in only one of the directories, diff
normally does not show the contents of the file that exists; it reports
only that the file exists in that directory and not in the other. You
can make diff act as though the file existed but was empty in the
other directory, so that it outputs the entire contents of the file that
actually exists. (It is output as either an insertion or a
deletion, depending on whether it is in the first or the second
directory given.) To do this, use the -N or --new-file
option.
If the older directory contains one or more large files that are not in
the newer directory, you can make the patch smaller by using the
--unidirectional-new-file option instead of -N.
This option is like -N except that it only inserts the contents
of files that appear in the second directory but not the first (that is,
files that were added). At the top of the patch, write instructions for
the user applying the patch to remove the files that were deleted before
applying the patch. See Making Patches, for more discussion of
making patches for distribution.
To ignore some files while comparing directories, use the -x
pattern or --exclude=pattern option. This option
ignores any files or subdirectories whose base names match the shell
pattern pattern. Unlike in the shell, a period at the start of
the base of a file name matches a wildcard at the start of a pattern.
You should enclose pattern in quotes so that the shell does not
expand it. For example, the option -x '*.[ao]' ignores any file
whose name ends with .a or .o.
This option accumulates if you specify it more than once. For example,
using the options -x 'RCS' -x '*,v' ignores any file or
subdirectory whose base name is RCS or ends with ,v.
If you need to give this option many times, you can instead put the
patterns in a file, one pattern per line, and use the -X
file or --exclude-from=file option.
If you have been comparing two directories and stopped partway through,
later you might want to continue where you left off. You can do this by
using the -S file or --starting-file=file
option. This compares only the file file and all alphabetically
later files in the topmost directory level.
If two directories differ only in that file names are lower case in
one directory and upper case in the upper, diff normally
reports many differences because it compares file names in a
case sensitive way. With the --ignore-file-name-case option,
diff ignores case differences in file names, so that for example
the contents of the file Tao in one directory are compared to
the contents of the file TAO in the other. The
--no-ignore-file-name-case option cancels the effect of the
--ignore-file-name-case option, reverting to the default
behavior.
If an -x pattern, --exclude=pattern,
-X file, or --exclude-from=file option
is specified while the --ignore-file-name-case option is in
effect, case is ignored when excluding file names matching the
specified patterns.
diff Output Prettierdiff provides several ways to adjust the appearance of its output.
These adjustments can be applied to any output format.
diff output.
The lines of text in some of the diff output formats are preceded
by one or two characters that indicate whether the text is inserted,
deleted, or changed. The addition of those characters can cause tabs to
move to the next tab stop, throwing off the alignment of columns in the
line. GNU diff provides two ways to make tab-aligned columns
line up correctly.
The first way is to have diff convert all tabs into the correct
number of spaces before outputting them; select this method with the
-t or --expand-tabs option. diff assumes that
tab stops are set every 8 print columns. To use this form of output with
patch, you must give patch the -l or
--ignore-white-space option (see Changed White Space, for more
information).
The other method for making tabs line up correctly is to add a tab
character instead of a space after the indicator character at the
beginning of the line. This ensures that all following tab characters
are in the same position relative to tab stops that they were in the
original files, so that the output is aligned correctly. Its
disadvantage is that it can make long lines too long to fit on one line
of the screen or the paper. It also does not work with the unified
output format, which does not have a space character after the change
type indicator character. Select this method with the -T or
--initial-tab option.
diff OutputIt can be convenient to have long output page-numbered and time-stamped.
The -l and --paginate options do this by sending the
diff output through the pr program. Here is what the page
header might look like for diff -lc lao tzu:
2002-02-22 14:20 diff -lc lao tzu Page 1
diff Performance TradeoffsGNU diff runs quite efficiently; however, in some circumstances
you can cause it to run faster or produce a more compact set of changes.
One way to improve diff performance is to use hard or
symbolic links to files instead of copies. This improves performance
because diff normally does not need to read two hard or
symbolic links to the same file, since their contents must be
identical. For example, suppose you copy a large directory hierarchy,
make a few changes to the copy, and then often use diff -r to
compare the original to the copy. If the original files are
read-only, you can greatly improve performance by creating the copy
using hard or symbolic links (e.g., with GNU cp -lR or
cp -sR). Before editing a file in the copy for the first time,
you should break the link and replace it with a regular copy.
You can also affect the performance of GNU diff by
giving it options that change the way it compares files.
Performance has more than one dimension. These options improve one
aspect of performance at the cost of another, or they improve
performance in some cases while hurting it in others.
The way that GNU diff determines which lines have changed always
comes up with a near-minimal set of differences. Usually it is good
enough for practical purposes. If the diff output is large, you
might want diff to use a modified algorithm that sometimes
produces a smaller set of differences. The -d or
--minimal option does this; however, it can also cause
diff to run more slowly than usual, so it is not the default
behavior.
When the files you are comparing are large and have small groups of
changes scattered throughout them, you can use the
--speed-large-files option to make a different modification to
the algorithm that diff uses. If the input files have a constant
small density of changes, this option speeds up the comparisons without
changing the output. If not, diff might produce a larger set of
differences; however, the output will still be correct.
Normally diff discards the prefix and suffix that is common to
both files before it attempts to find a minimal set of differences.
This makes diff run faster, but occasionally it may produce
non-minimal output. The --horizon-lines=lines option
prevents diff from discarding the last lines lines of the
prefix and the first lines lines of the suffix. This gives
diff further opportunities to find a minimal output.
Suppose a run of changed lines includes a sequence of lines at one end
and there is an identical sequence of lines just outside the other end.
The diff command is free to choose which identical sequence is
included in the hunk. In this case, diff normally shifts the
hunk's boundaries when this merges adjacent hunks, or shifts a hunk's
lines towards the end of the file. Merging hunks can make the output
look nicer in some cases.
Use the program diff3 to compare three files and show any
differences among them. (diff3 can also merge files; see
diff3 Merging).
The "normal" diff3 output format shows each hunk of
differences without surrounding context. Hunks are labeled depending
on whether they are two-way or three-way, and lines are annotated by
their location in the input files.
See Invoking diff3, for more information on how to run diff3.
diff3 input for examples.
Here is a third sample file that will be used in examples to illustrate
the output of diff3 and how various options can change it. The
first two files are the same that we used for diff (see Sample diff Input). This is the third sample file, called tao:
The Way that can be told of is not the eternal Way; The name that can be named is not the eternal name. The Nameless is the origin of Heaven and Earth; The named is the mother of all things. Therefore let there always be non-being, so we may see their subtlety, And let there always be being, so we may see their result. The two are the same, But after they are produced, they have different names. -- The Way of Lao-Tzu, tr. Wing-tsit Chan
diff3 Normal FormatEach hunk begins with a line marked ====. Three-way hunks have
plain ==== lines, and two-way hunks have 1, 2, or
3 appended to specify which of the three input files differ in
that hunk. The hunks contain copies of two or three sets of input
lines each preceded by one or two commands identifying where the lines
came from.
Normally, two spaces precede each copy of an input line to distinguish
it from the commands. But with the -T or --initial-tab
option, diff3 uses a tab instead of two spaces; this lines up
tabs correctly. See Tabs, for more information.
Commands take the following forms:
file:la
1:11a means that the hunk follows line 11 in the first
file and contains no lines from that file.
file:rc
2:11,13c means that the hunk
contains lines 11 through 13 from the second file.
If the last line in a set of input lines is incomplete
(see Incomplete Lines), it is distinguished on output from a full
line by a following line that starts with \.
diff3 HunksGroups of lines that differ in two or three of the input files are
called diff3 hunks, by analogy with diff hunks
(see Hunks). If all three input files differ in a diff3
hunk, the hunk is called a three-way hunk; if just two input files
differ, it is a two-way hunk.
As with diff, several solutions are possible. When comparing the
files A, B, and C, diff3 normally finds
diff3 hunks by merging the two-way hunks output by the two
commands diff A B and diff A C. This does not necessarily
minimize the size of the output, but exceptions should be rare.
For example, suppose F contains the three lines a,
b, f, G contains the lines g, b,
g, and H contains the lines a, b,
h. diff3 F G H might output the following:
====2 1:1c 3:1c a 2:1c g ==== 1:3c f 2:3c g 3:3c h
because it found a two-way hunk containing a in the first and
third files and g in the second file, then the single line
b common to all three files, then a three-way hunk containing
the last line of each file.
diff3 Normal FormatHere is the output of the command diff3 lao tzu tao
(see Sample diff3 Input, for the complete contents of the files).
Notice that it shows only the lines that are different among the three
files.
====2
1:1,2c
3:1,2c
The Way that can be told of is not the eternal Way;
The name that can be named is not the eternal name.
2:0a
====1
1:4c
The Named is the mother of all things.
2:2,3c
3:4,5c
The named is the mother of all things.
====3
1:8c
2:7c
so we may see their outcome.
3:9c
so we may see their result.
====
1:11a
2:11,13c
They both may be called deep and profound.
Deeper and more profound,
The door of all subtleties!
3:13,14c
-- The Way of Lao-Tzu, tr. Wing-tsit Chan
When two people have made changes to copies of the same file,
diff3 can produce a merged output that contains both sets of
changes together with warnings about conflicts.
One might imagine programs with names like diff4 and diff5
to compare more than three files simultaneously, but in practice the
need rarely arises. You can use diff3 to merge three or more
sets of changes to a file by merging two change sets at a time.
diff3 can incorporate changes from two modified versions into a
common preceding version. This lets you merge the sets of changes
represented by the two newer files. Specify the common ancestor version
as the second argument and the two newer versions as the first and third
arguments, like this:
diff3 mine older yours
You can remember the order of the arguments by noting that they are in alphabetical order.
You can think of this as subtracting older from yours and adding the result to mine, or as merging into mine the changes that would turn older into yours. This merging is well-defined as long as mine and older match in the neighborhood of each such change. This fails to be true when all three input files differ or when only older differs; we call this a conflict. When all three input files differ, we call the conflict an overlap.
diff3 gives you several ways to handle overlaps and conflicts.
You can omit overlaps or conflicts, or select only overlaps,
or mark conflicts with special <<<<<<< and >>>>>>> lines.
diff3 can output the merge results as an ed script that
that can be applied to the first file to yield the merged output.
However, it is usually better to have diff3 generate the merged
output directly; this bypasses some problems with ed.
diff3 merges incomplete lines.
You can select all unmerged changes from older to yours for merging
into mine with the -e or --ed option. You can
select only the nonoverlapping unmerged changes with -3 or
--easy-only, and you can select only the overlapping changes with
-x or --overlap-only.
The -e, -3 and -x options select only
unmerged changes, i.e. changes where mine and yours
differ; they ignore changes from older to yours where
mine and yours are identical, because they assume that such
changes have already been merged. If this assumption is not a safe
one, you can use the -A or --show-all option
(see Marking Conflicts).
Here is the output of the command diff3 with each of these three
options (see Sample diff3 Input, for the complete contents of the files).
Notice that -e outputs the union of the disjoint sets of changes
output by -3 and -x.
Output of diff3 -e lao tzu tao:
11a -- The Way of Lao-Tzu, tr. Wing-tsit Chan . 8c so we may see their result. .
Output of diff3 -3 lao tzu tao:
8c so we may see their result. .
Output of diff3 -x lao tzu tao:
11a -- The Way of Lao-Tzu, tr. Wing-tsit Chan .
diff3 can mark conflicts in the merged output by
bracketing them with special marker lines. A conflict
that comes from two files A and B is marked as follows:
<<<<<<< A lines from A ======= lines from B >>>>>>> B
A conflict that comes from three files A, B and C is
marked as follows:
<<<<<<< A lines from A ||||||| B lines from B ======= lines from C >>>>>>> C
The -A or --show-all option acts like the -e
option, except that it brackets conflicts, and it outputs all changes
from older to yours, not just the unmerged changes. Thus,
given the sample input files (see Sample diff3 Input), diff3
-A lao tzu tao puts brackets around the conflict where only tzu
differs:
<<<<<<< tzu ======= The Way that can be told of is not the eternal Way; The name that can be named is not the eternal name. >>>>>>> tao
And it outputs the three-way conflict as follows:
<<<<<<< lao ||||||| tzu They both may be called deep and profound. Deeper and more profound, The door of all subtleties! ======= -- The Way of Lao-Tzu, tr. Wing-tsit Chan >>>>>>> tao
The -E or --show-overlap option outputs less information
than the -A or --show-all option, because it outputs only
unmerged changes, and it never outputs the contents of the second
file. Thus the -E option acts like the -e option,
except that it brackets the first and third files from three-way
overlapping changes. Similarly, -X acts like -x, except
it brackets all its (necessarily overlapping) changes. For example,
for the three-way overlapping change above, the -E and -X
options output the following:
<<<<<<< lao ======= -- The Way of Lao-Tzu, tr. Wing-tsit Chan >>>>>>> tao
If you are comparing files that have meaningless or uninformative names,
you can use the -L label or --label=label
option to show alternate names in the <<<<<<<, |||||||
and >>>>>>> brackets. This option can be given up to three
times, once for each input file. Thus diff3 -A -L X -L Y -L Z A
B C acts like diff3 -A A B C, except that the output looks like
it came from files named X, Y and Z rather than
from files named A, B and C.
With the -m or --merge option, diff3 outputs the
merged file directly. This is more efficient than using ed to
generate it, and works even with non-text files that ed would
reject. If you specify -m without an ed script option,
-A (--show-all) is assumed.
For example, the command diff3 -m lao tzu tao
(see Sample diff3 Input for a copy of the input files) would output
the following:
<<<<<<< tzu ======= The Way that can be told of is not the eternal Way; The name that can be named is not the eternal name. >>>>>>> tao The Nameless is the origin of Heaven and Earth; The Named is the mother of all things. Therefore let there always be non-being, so we may see their subtlety, And let there always be being, so we may see their result. The two are the same, But after they are produced, they have different names. <<<<<<< lao ||||||| tzu They both may be called deep and profound. Deeper and more profound, The door of all subtleties! ======= -- The Way of Lao-Tzu, tr. Wing-tsit Chan >>>>>>> tao
diff3 Merges Incomplete LinesWith -m, incomplete lines (see Incomplete Lines) are simply
copied to the output as they are found; if the merged output ends in an
conflict and one of the input files ends in an incomplete
line, succeeding |||||||, ======= or >>>>>>>
brackets appear somewhere other than the start of a line because
they are appended to the incomplete line.
Without -m, if an ed script option is specified and an
incomplete line is found, diff3 generates a warning and acts as
if a newline had been present.
Traditional Unix diff3 generates an ed script without the
trailing w and q commands that save the changes.
System V diff3 generates these extra commands. GNU
diff3 normally behaves like traditional Unix
diff3, but with the -i option it behaves like
System V diff3 and appends the w and q
commands.
The -i option requires one of the ed script options
-AeExX3, and is incompatible with the merged output option
-m.
sdiffWith sdiff, you can merge two files interactively based on a
side-by-side -y format comparison (see Side by Side). Use
-o file or --output=file to specify where to
put the merged text. See Invoking sdiff, for more details on the
options to sdiff.
Another way to merge files interactively is to use the Emacs Lisp
package emerge. See emerge, for more information.
sdiff options.
diff Options to sdiffThe following sdiff options have the same meaning as for
diff. See diff Options, for the use of these options.
-a -b -d -i -t -v -B -E -I regexp --ignore-blank-lines --ignore-case --ignore-matching-lines=regexp --ignore-space-change --ignore-tab-expansion --left-column --minimal --speed-large-files --strip-trailing-cr --suppress-common-lines --expand-tabs --text --version --width=columns
For historical reasons, sdiff has alternate names for some
options. The -l option is equivalent to the
--left-column option, and similarly -s is equivalent
to --suppress-common-lines. The meaning of the sdiff
-w and -W options is interchanged from that of
diff: with sdiff, -w columns is
equivalent to --width=columns, and -W is
equivalent to --ignore-all-space. sdiff without the
-o option is equivalent to diff with the -y
or --side-by-side option (see Side by Side).
Groups of common lines, with a blank gutter, are copied from the first
file to the output. After each group of differing lines, sdiff
prompts with % and pauses, waiting for one of the following
commands. Follow each command with <RET>.
e
eb
ed
eb, except precede each version with a header that
shows what file and lines the version came from.
el
er
l
q
r
s
v
The text editor invoked is specified by the EDITOR environment
variable if it is set. The default is system-dependent.
patchpatch takes comparison output produced by diff and applies
the differences to a copy of the original file, producing a patched
version. With patch, you can distribute just the changes to a
set of files instead of distributing the entire file set; your
correspondents can apply patch to update their copy of the files
with your changes. patch automatically determines the diff
format, skips any leading or trailing headers, and uses the headers to
determine which file to patch. This lets your correspondents feed a
mail message containing a difference listing directly to
patch.
patch detects and warns about common problems like forward
patches. It saves any patches that it could not apply. It can also maintain a
patchlevel.h file to ensure that your correspondents apply
diffs in the proper order.
patch accepts a series of diffs in its standard input, usually
separated by headers that specify which file to patch. It applies
diff hunks (see Hunks) one by one. If a hunk does not
exactly match the original file, patch uses heuristics to try to
patch the file as well as it can. If no approximate match can be found,
patch rejects the hunk and skips to the next hunk. patch
normally replaces each file f with its new version, putting reject
hunks (if any) into f.rej.
See Invoking patch, for detailed information on the options to
patch.
patch input.
patch can produce.
patch.
patch Input Formatpatch normally determines which diff format the patch
file uses by examining its contents. For patch files that contain
particularly confusing leading text, you might need to use one of the
following options to force patch to interpret the patch file as a
certain format of diff. The output formats listed here are the only
ones that patch can understand.
-c
--context
-e
--ed
ed script.
-n
--normal
-u
--unified
If a nonexistent input file is under a revision control system
supported by patch, patch normally asks the user
whether to get (or check out) the file from the revision control
system. Patch currently supports RCS, ClearCase and SCCS.
Under RCS and SCCS, patch also asks when the input
file is read-only and matches the default version in the revision
control system.
The -g num or --get=num affects access
to files under supported revision control systems. If num is
positive