diff(1) User Commands diff(1)NAMEdiff - compare two files
SYNOPSISdiff [-bitw] [-c | -e | -f | -h | -n | -u] file1 file2
diff [-bitw] [-C number | -U number] file1 file2
diff [-bitw] [-D string] file1 file2
diff [-bitw] [-c | -e | -f | -h | -n | -u] [-l] [-r] [-s] [-S name]
directory1 directory2
DESCRIPTION
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. Except in rare circumstances, diff
finds a smallest sufficient set of file differences. 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 `>'.
OPTIONS
The following options are supported:
-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 com‐
pare 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. That is, 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 '—'. The lines
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.
-D string Creates a merged version of file1 and file2 with C pre‐
processor controls included so that a compilation of
the result without defining string is equivalent to
compiling file1, while defining string will yield
file2.
-e Produces a script of only a, c, and d commands for the
editor ed, which will recreate file2 from file1. In
connection with the -e option, the following shell pro‐
gram 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 out‐
put.
(shift; cat $*; echo '1,$p') | ed − $1
-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, -C,
-D, -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.
-u Produces a listing of differences with three lines of
context. The output is similar to that of the -c
option, except that the context is "unified". Removed
and changed lines in file1 are marked by a '-' while
lines added or changed in file2 are marked by a '+'.
Both versions of changed lines appear in the output,
while added, removed, and context lines appear only
once. The identification of file1 and file2 is differ‐
ent, with "−−−" and "+++" being printed where "***" and
"−−−" would appear with the -c option. Each change is
separated by a line of the form
@@ -n1,n2 +n3,n4 @@
-U number Produces a listing of differences identical to that
produced by -u with number lines of context.
The following options are used for comparing directories:
-l Produces 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 identical. These identical files
would not otherwise be mentioned.
-S name Starts a directory diff in the middle, beginning with
the file name.
OPERANDS
The following operands are supported:
file1 A path name of a file or directory to be compared. If
file2 either file1 or file2 is −, the standard input will be
used in its place.
directory1 A path name of a directory to be compared.
directory2
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.
USAGE
See largefile(5) for the description of the behavior of diff when
encountering files greater than or equal to 2 Gbyte ( 2**31 bytes).
EXAMPLES
Example 1: Typical output of the diff command
In the following command, 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:
example% diff-r dir1 dir2
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
ENVIRONMENT VARIABLES
See environ(5) for descriptions of the following environment variables
that affect the execution of diff: LANG, LC_ALL, LC_CTYPE, LC_MESSAGES,
LC_TIME, and NLSPATH.
TZ Determines the locale for affecting the timezone used for cal‐
culating file timestamps written with the -C and -c options.
EXIT STATUS
The following exit values are returned:
0 No differences were found.
1 Differences were found.
>1 An error occurred.
FILES
/tmp/d????? temporary file used for comparison
/usr/lib/diffh executable file for -h option
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │SUNWesu │
├─────────────────────────────┼─────────────────────────────┤
│CSI │Enabled │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSObdiff(1), cmp(1), comm(1), dircmp(1), ed(1), pr(1), sdiff( 1),
attributes(5), environ(5), largefile(5), standards(5)NOTES
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.
SunOS 5.10 22 Sep 2004 diff(1)
