diff(1) manual page
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diff - display line-by-line differences between pairs of text files
diff [ -bitw ] [ -c | -e | -f | -h | -n ] file1 file2
diff [ -bitw ] [ -C number ] file1 file2
diff [ -bitw ] [ -D string ] file1 file2
diff [ -bitw ] [ -c | -e | -f | -h | -n ] [ -l ] [ -r ] [ -s ] [ -S name ] directory1
directory2
SUNWesu
The diff utility will compare
the contents of file1 and file2 and write to standard output a list of
changes necessary to convert file1 into file2. This list should be minimal.
No output will be produced if the files are identical.
The normal output
contains lines of these forms:
- n1
- a n3,n4
n1,n2 d n3
n1,n2 c n3,n4
where n1 and n2 represent lines file1 and n3 and n4 represent
lines in file2 These lines resemble ed(1)
commands to convert file1 to
file2. By exchanging a for d and reading backward, file2 can be converted
to file1. As in ed, identical pairs, where n1=n2 or n3=n4, are abbreviated
as a single number.
Following each of these lines come all the lines that
are affected in the first file flagged by ‘<’, then all the lines that are
affected in the second file flagged by ‘>’.
- -b
- Ignores trailing blanks
(spaces and tabs) and treats other strings of blanks as equivalent.
- -i
- Ignores
the case of letters; for example, ‘A’ will compare equal to ‘a’.
- -t
- Expands TAB
characters in output lines. Normal or -c output adds character(s) to the
front of each line that may adversely affect the indentation of the original
source lines and make the output lines difficult to interpret. This option
will preserve the original source’s indentation.
- -w
- Ignores all blanks (SPACE
and TAB
characters) and treats all other strings of blanks as equivalent;
for example, ‘if ( a == b )’ will compare equal to ‘if(a==b)’.
The following options
are mutually exclusive:
- -c
- Produces a listing of differences with three
lines of context. With this option output format is modified slightly: output
begins with identification of the files involved and their creation dates,
then each change is separated by a line with a dozen *’s. The lines removed
from file1 are marked with ’--’; those added to file2 are marked ’+’. Lines that
are changed from one file to the other are marked in both files with ’!’.
- -C number
- Produces a listing of differences identical to that produced
by -c with number lines of context.
- -e
- Produces a script of only a, c, and d commands for the editor ed, which
will recreate file2 from file1. In connection with -e, the following shell
program may help maintain multiple versions of a file. Only an ancestral
file ($1) and a chain of version-to-version ed scripts ($2,$3,...) made by
diff need be on hand. A ‘‘latest version’’ appears on the standard output.
- (shift;
cat $*; echo fm1,$pfm) | ed - $1
Except in rare circumstances, diff finds
a smallest sufficient set of file differences.
- -f
- Produces a similar script,
not useful with ed, in the opposite order.
- -h
- Does a fast, half-hearted job.
It works only when changed stretches are short and well separated, but
does work on files of unlimited length. Options -c, -e, -f, and -n are unavailable
with -h. diff does not descend into directories with this option.
- -n
- Produces
a script similar to -e, but in the opposite order and with a count of changed
lines on each insert or delete command.
- -D string
- Creates a merged version
of file1 and file2 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.
The following options are used for
comparing directories:
- -l
- Produce output in long format. Before the diff,
each text file is piped through pr(1)
to paginate it. Other differences
are remembered and summarized after all text file differences are reported.
- -r
- Applies diff recursively to common subdirectories encountered.
- -s
- Reports
files that are the identical; these would not otherwise be mentioned.
- -S
name
- Starts a directory diff in the middle, beginning with the file name.
The following operands are supported:
file1
- file2
- A path name
of a file or directory to be compared. If either file1 or file2 is -, the
standard input will be used in its place.
directory1
- directory2
- A path
name of a directory to be compared.
If only one of file1 and file2 is a
directory, diff will be 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 non-directory file.
If dir1 is a directory containing a directory
named x, dir2 is a directory containing a directory named x, dir1/x and
dir2/x both contain files named date.out, and dir2/x contains a file named
y, the command: example% diff -r dir1 dir2
could produce output similar
to:
Common subdirectories: dir1/x and dir2/x
Only in dir2/x: y
diff -r dir1/x/date.out dir2/x/date.out
1c1
< Mon Jul 2 13:12:16 PDT 1990
---
> Tue Jun 19 21:41:39 PDT 1990
See environ(5)
for descriptions of the following environment
variables that affect the execution of diff: LC_CTYPE
, LC_MESSAGES
, and
NLSPATH
.
- LC_TIME
- Determine the locale for affecting the format of file
timestamps written with the -C and -c options.
- TZ
- Determine the locale for
affecting the timezone used for calculating file timestamps written with
the -C and -c options.
The following exit values are returned:
- No differences were found.
- Differences were found.
- >1
- An error occurred.
- /tmp/d?????
- temporary file used for comparison
- /usr/lib/diffh
- executable file for
-h option
bdiff(1)
, cmp(1)
, comm(1)
, dircmp(1)
, ed(1)
, pr(1)
, sdiff(1)
,
environ(5)
Editing scripts produced under the -e or -f options are
naive about creating lines consisting of a single period (.).
Missing NEWLINE
at end of file indicates that the last line of the file in question did
not have a NEWLINE.
If the lines are different, they will be flagged and
output; although the output will seem to indicate they are the same.
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