diff - differential file and directory comparator
diff [-abdilpqtTw] [-I pattern] [-c | -e | -f | -n | -u] [-L
label] file1
file2
diff [-abdilpqtTw] [-I pattern] [-L label] -C number file1
file2
diff [-abdilqtw] [-I pattern] -D string file1 file2
diff [-abdilpqtTw] [-I pattern] [-L label] -U number file1
file2
diff [-abdilNPpqtTw] [-I pattern] [-c | -e | -f | -n | -u]
[-L label]
[-r] [-s] [-S name] [-X file] [-x pattern] dir1 dir2
The diff utility compares the contents of file1 and file2
and writes to
the standard output the list of changes necessary to convert
one file into
the other. No output is produced if the files are identical.
Output options (mutually exclusive):
-c Produces a diff with 3 lines of context. With -c
the output format
is modified slightly: the output begins with
identification
of the files involved and their creation dates and
then each
change is separated by a line with fifteen *'s. The
lines removed
from file1 are marked with `- '; those added
to file2 are
marked `+ '. Lines which are changed from one file
to the other
are marked in both files with `! '. Changes which
lie within 3
lines of each other are grouped together on output.
-e Produces output in a form suitable as input for the
editor utility,
ed(1), which can then be used to convert file1
into file2.
Extra commands are added to the output when comparing directories
with -e, so that the result is a sh(1) script for
converting text
files which are common to the two directories from
their state in
dir1 to their state in dir2.
-f Identical output to that of the -e flag, but in reverse order.
It cannot be digested by ed(1).
-n Produces a script similar to that of -e, but in the
opposite order
and with a count of changed lines on each insert
or delete
command. This is the form used by rcsdiff(1).
-q Just print a line when the files differ. Does not
output a list
of changes.
-u Produces a unified diff with 3 lines of context. A
unified diff
is similar to the context diff produced by the -c
option. However,
unlike with -c, all lines to be changed (added
and/or removed)
are present in a single section.
-C number
Like -c but produces a diff with number lines of
context.
-D string
Creates a merged version of file1 and file2 on the
standard output,
with C preprocessor controls included so that a
compilation
of the result without defining string is equivalent
to compiling
file1, while defining string will yield file2.
-U number
Like -u but produces a diff with number lines of
context.
Comparison options:
-a Treat all files as ASCII.
-b Causes trailing blanks (spaces and tabs) to be ignored, and other
strings of blanks to compare equal.
-d Try very hard to produce a diff as small as possible. This may
consume a lot of processing power and memory when
processing
large files with many changes.
-I pattern
Ignores changes, insertions, and deletions whose
lines match the
extended regular expression pattern. Multiple -I
patterns may be
specified. All lines in the change must match some
pattern for
the change to be ignored. See re_format(7) for more
information
on regular expression patterns.
-i Ignores the case of letters. E.g., ``A'' will compare equal to
``a''.
-l Long output format; each text file diff'd is piped
through pr(1)
to paginate it; other differences are remembered and
summarized
after all text file differences are reported.
-L label
Print label instead of the first file name and time
in the context
or unified diff header.
-p With unified and context diffs, show with each
change the first
40 characters of the last line before the context
beginning with
a letter, an underscore or a dollar sign. For C
source code following
standard layout conventions, this will show
the prototype
of the function the change applies to.
-t Will expand tabs in output lines. Normal or -c output adds character(s)
to the front of each line which may screw
up the indentation
of the original source lines and make the
output listing
difficult to interpret. This option will preserve
the original
source's indentation.
-T Print a tab rather than a space before the rest of
the line for
the normal, context or unified output formats. This
makes the
alignment of tabs in the line consistent.
-w Is similar to -b but causes whitespace (blanks and
tabs) to be
totally ignored. E.g., ``if ( a == b )'' will compare equal to
``if(a==b)''.
Directory comparison options:
-N If a file is found in only one directory, act as if
it was found
in the other directory too but was of zero size.
-P If a file is found only in dir2, act as if it was
found in dir1
too but was of zero size.
-r Causes application of diff recursively to common
subdirectories
encountered.
-s Causes diff to report files which are the same,
which are otherwise
not mentioned.
-S name
Re-starts a directory diff in the middle, beginning
with file
name.
-X file
Exclude files and subdirectories from comparison
whose basenames
match lines in file. Multiple -X options may be
specified.
-x pattern
Exclude files and subdirectories from comparison
whose basenames
match pattern. Patterns are matched using shellstyle globbing
via fnmatch(3). Multiple -x options may be specified.
If both arguments are directories, diff sorts the contents
of the directories
by name, and then runs the regular file diff algorithm, producing
a change list, on text files which are different. Binary
files which
differ, common subdirectories, and files which appear in only one directory
are described as such. In directory mode only regular
files and directories
are compared. If a non-regular file such as a device special
file or FIFO is encountered, a diagnostic message is printed.
If only one of file1 and file2 is a directory, diff is applied to the
non-directory file and the file contained in the directory
file with a
filename that is the same as the last component of the nondirectory
file.
If either file1 or file2 is `-', the standard input is used
in its place.
Output Style [Toc] [Back]
The default (without -e, -c, or -n options) output contains
lines of
these forms, where XX, YY, ZZ, QQ are line numbers respective of file order.
XXaYY At (the end of) line XX of file1, append the
contents of
line YY of file2 to make them equal.
XXaYY,ZZ Same as above, but append the range of lines,
YY through ZZ
of file2 to line XX of file1.
XXdYY At line XX delete the line. The value YY tells
to which
line the change would bring file1 in line with
file1.
XX,YYdZZ Delete the range of lines XX through YY in
file1.
XXcYY Change the line XX in file1 to the line YY in
file2.
XX,YYcZZ Replace the range of specified lines with the
line ZZ.
XX,YYcZZ,QQ Replace the range XX,YY from file1 with the
range ZZ,QQ from
file2.
These lines resemble ed(1) subcommands to convert file1 into
file2. The
line numbers before the action letters pertain to file1;
those after pertain
to file2. Thus, by exchanging a for d and reading the
line in reverse
order, one can also determine how to convert file2 into file1. As
in ed(1), identical pairs (where num1 = num2) are abbreviated as a single
number.
TMPDIR If the environment variable TMPDIR exists, diff will
use the directory
specified by TMPDIR as the temporary directory.
/tmp/diff.XXXXXXXX Temporary file used when comparing a device or the
standard input. Note that the temporary
file is unlinked
as soon as it is created so it
will not show
up in a directory listing.
The diff utility exits with one of the following values:
0 No differences were found.
1 Differences were found.
>1 An error occurred.
cmp(1), comm(1), diff3(1), ed(1), pr(1), fnmatch(3), re_format(7)
The diff utility is expected to be a superset of the IEEE
Std 1003.1-2001
(``POSIX'') specification.
A diff command appeared in Version 6 AT&T UNIX.
When comparing directories with the -b, -w or -i options
specified, diff
first compares the files ala cmp(1), and then decides to run
the diff algorithm
if they are not equal. This may cause a small
amount of spurious
output if the files then turn out to be identical because
the only differences
are insignificant whitespace or case differences.
OpenBSD 3.6 July 21, 2003
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